arm64: Rewrite Spectre-v4 mitigation code

[mirror_ubuntu-jammy-kernel.git] / arch / arm64 / kernel / cpufeature.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Contains CPU feature definitions
 *
 * Copyright (C) 2015 ARM Ltd.
 *
 * A note for the weary kernel hacker: the code here is confusing and hard to
 * follow! That's partly because it's solving a nasty problem, but also because
 * there's a little bit of over-abstraction that tends to obscure what's going
 * on behind a maze of helper functions and macros.
 *
 * The basic problem is that hardware folks have started gluing together CPUs
 * with distinct architectural features; in some cases even creating SoCs where
 * user-visible instructions are available only on a subset of the available
 * cores. We try to address this by snapshotting the feature registers of the
 * boot CPU and comparing these with the feature registers of each secondary
 * CPU when bringing them up. If there is a mismatch, then we update the
 * snapshot state to indicate the lowest-common denominator of the feature,
 * known as the "safe" value. This snapshot state can be queried to view the
 * "sanitised" value of a feature register.
 *
 * The sanitised register values are used to decide which capabilities we
 * have in the system. These may be in the form of traditional "hwcaps"
 * advertised to userspace or internal "cpucaps" which are used to configure
 * things like alternative patching and static keys. While a feature mismatch
 * may result in a TAINT_CPU_OUT_OF_SPEC kernel taint, a capability mismatch
 * may prevent a CPU from being onlined at all.
 *
 * Some implementation details worth remembering:
 *
 * - Mismatched features are *always* sanitised to a "safe" value, which
 *   usually indicates that the feature is not supported.
 *
 * - A mismatched feature marked with FTR_STRICT will cause a "SANITY CHECK"
 *   warning when onlining an offending CPU and the kernel will be tainted
 *   with TAINT_CPU_OUT_OF_SPEC.
 *
 * - Features marked as FTR_VISIBLE have their sanitised value visible to
 *   userspace. FTR_VISIBLE features in registers that are only visible
 *   to EL0 by trapping *must* have a corresponding HWCAP so that late
 *   onlining of CPUs cannot lead to features disappearing at runtime.
 *
 * - A "feature" is typically a 4-bit register field. A "capability" is the
 *   high-level description derived from the sanitised field value.
 *
 * - Read the Arm ARM (DDI 0487F.a) section D13.1.3 ("Principles of the ID
 *   scheme for fields in ID registers") to understand when feature fields
 *   may be signed or unsigned (FTR_SIGNED and FTR_UNSIGNED accordingly).
 *
 * - KVM exposes its own view of the feature registers to guest operating
 *   systems regardless of FTR_VISIBLE. This is typically driven from the
 *   sanitised register values to allow virtual CPUs to be migrated between
 *   arbitrary physical CPUs, but some features not present on the host are
 *   also advertised and emulated. Look at sys_reg_descs[] for the gory
 *   details.
 *
 * - If the arm64_ftr_bits[] for a register has a missing field, then this
 *   field is treated as STRICT RES0, including for read_sanitised_ftr_reg().
 *   This is stronger than FTR_HIDDEN and can be used to hide features from
 *   KVM guests.
 */

#define pr_fmt(fmt) "CPU features: " fmt

#include <linux/bsearch.h>
#include <linux/cpumask.h>
#include <linux/crash_dump.h>
#include <linux/sort.h>
#include <linux/stop_machine.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <asm/cpu.h>
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/fpsimd.h>
#include <asm/mmu_context.h>
#include <asm/processor.h>
#include <asm/sysreg.h>
#include <asm/traps.h>
#include <asm/virt.h>

/* Kernel representation of AT_HWCAP and AT_HWCAP2 */
static unsigned long elf_hwcap __read_mostly;

#ifdef CONFIG_COMPAT
#define COMPAT_ELF_HWCAP_DEFAULT        \
                                (COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\
                                 COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
                                 COMPAT_HWCAP_TLS|COMPAT_HWCAP_IDIV|\
                                 COMPAT_HWCAP_LPAE)
unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
unsigned int compat_elf_hwcap2 __read_mostly;
#endif

DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
EXPORT_SYMBOL(cpu_hwcaps);
static struct arm64_cpu_capabilities const __ro_after_init *cpu_hwcaps_ptrs[ARM64_NCAPS];

/* Need also bit for ARM64_CB_PATCH */
DECLARE_BITMAP(boot_capabilities, ARM64_NPATCHABLE);

bool arm64_use_ng_mappings = false;
EXPORT_SYMBOL(arm64_use_ng_mappings);

/*
 * Flag to indicate if we have computed the system wide
 * capabilities based on the boot time active CPUs. This
 * will be used to determine if a new booting CPU should
 * go through the verification process to make sure that it
 * supports the system capabilities, without using a hotplug
 * notifier. This is also used to decide if we could use
 * the fast path for checking constant CPU caps.
 */
DEFINE_STATIC_KEY_FALSE(arm64_const_caps_ready);
EXPORT_SYMBOL(arm64_const_caps_ready);
static inline void finalize_system_capabilities(void)
{
        static_branch_enable(&arm64_const_caps_ready);
}

void dump_cpu_features(void)
{
        /* file-wide pr_fmt adds "CPU features: " prefix */
        pr_emerg("0x%*pb\n", ARM64_NCAPS, &cpu_hwcaps);
}

DEFINE_STATIC_KEY_ARRAY_FALSE(cpu_hwcap_keys, ARM64_NCAPS);
EXPORT_SYMBOL(cpu_hwcap_keys);

#define __ARM64_FTR_BITS(SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
        {                                               \
                .sign = SIGNED,                         \
                .visible = VISIBLE,                     \
                .strict = STRICT,                       \
                .type = TYPE,                           \
                .shift = SHIFT,                         \
                .width = WIDTH,                         \
                .safe_val = SAFE_VAL,                   \
        }

/* Define a feature with unsigned values */
#define ARM64_FTR_BITS(VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
        __ARM64_FTR_BITS(FTR_UNSIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL)

/* Define a feature with a signed value */
#define S_ARM64_FTR_BITS(VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
        __ARM64_FTR_BITS(FTR_SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL)

#define ARM64_FTR_END                                   \
        {                                               \
                .width = 0,                             \
        }

/* meta feature for alternatives */
static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused);

static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap);

static bool __system_matches_cap(unsigned int n);

/*
 * NOTE: Any changes to the visibility of features should be kept in
 * sync with the documentation of the CPU feature register ABI.
 */
static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RNDR_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TLB_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SM4_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SM3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RDM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_ATOMICS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_CRC32_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA1_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_AES_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_I8MM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_DGH_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_BF16_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_SPECRES_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_SB_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_FRINTTS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPI_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPA_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_LRCPC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_FCMA_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_JSCVT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_API_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_APA_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_DPB_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_DIT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_AMU_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_MPAM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SEL2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                                   FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_RAS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
        S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI),
        S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_FP_SHIFT, 4, ID_AA64PFR0_FP_NI),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_SHIFT, 4, ID_AA64PFR0_EL1_64BIT_ONLY),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL0_SHIFT, 4, ID_AA64PFR0_EL0_64BIT_ONLY),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_MPAMFRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_RASFRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_BTI),
                                    FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_BT_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64zfr0[] = {
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_F64MM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_F32MM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_I8MM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SM4_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SHA3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_BF16_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_BITPERM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_AES_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
                       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ZFR0_SVEVER_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr0[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_ECV_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_FGT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_EXS_SHIFT, 4, 0),
        /*
         * Page size not being supported at Stage-2 is not fatal. You
         * just give up KVM if PAGE_SIZE isn't supported there. Go fix
         * your favourite nesting hypervisor.
         *
         * There is a small corner case where the hypervisor explicitly
         * advertises a given granule size at Stage-2 (value 2) on some
         * vCPUs, and uses the fallback to Stage-1 (value 0) for other
         * vCPUs. Although this is not forbidden by the architecture, it
         * indicates that the hypervisor is being silly (or buggy).
         *
         * We make no effort to cope with this and pretend that if these
         * fields are inconsistent across vCPUs, then it isn't worth
         * trying to bring KVM up.
         */
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN4_2_SHIFT, 4, 1),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN64_2_SHIFT, 4, 1),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64MMFR0_TGRAN16_2_SHIFT, 4, 1),
        /*
         * We already refuse to boot CPUs that don't support our configured
         * page size, so we can only detect mismatches for a page size other
         * than the one we're currently using. Unfortunately, SoCs like this
         * exist in the wild so, even though we don't like it, we'll have to go
         * along with it and treat them as non-strict.
         */
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN4_SHIFT, 4, ID_AA64MMFR0_TGRAN4_NI),
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN64_SHIFT, 4, ID_AA64MMFR0_TGRAN64_NI),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN16_SHIFT, 4, ID_AA64MMFR0_TGRAN16_NI),

        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_BIGENDEL0_SHIFT, 4, 0),
        /* Linux shouldn't care about secure memory */
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_SNSMEM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_BIGENDEL_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_ASID_SHIFT, 4, 0),
        /*
         * Differing PARange is fine as long as all peripherals and memory are mapped
         * within the minimum PARange of all CPUs
         */
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_PARANGE_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr1[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_ETS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_TWED_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_XNX_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_HIGHER_SAFE, ID_AA64MMFR1_SPECSEI_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_PAN_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_LOR_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_HPD_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_VHE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_VMIDBITS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_HADBS_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_E0PD_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_EVT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_BBM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_TTL_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_FWB_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_IDS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_AT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_ST_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_NV_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_CCIDX_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LVA_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_IESB_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LSM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_UAO_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_CNP_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_ctr[] = {
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, 31, 1, 1), /* RES1 */
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_DIC_SHIFT, 1, 1),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_IDC_SHIFT, 1, 1),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_HIGHER_OR_ZERO_SAFE, CTR_CWG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_HIGHER_OR_ZERO_SAFE, CTR_ERG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_DMINLINE_SHIFT, 4, 1),
        /*
         * Linux can handle differing I-cache policies. Userspace JITs will
         * make use of *minLine.
         * If we have differing I-cache policies, report it as the weakest - VIPT.
         */
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_EXACT, CTR_L1IP_SHIFT, 2, ICACHE_POLICY_VIPT),   /* L1Ip */
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_IMINLINE_SHIFT, 4, 0),
        ARM64_FTR_END,
};

struct arm64_ftr_reg arm64_ftr_reg_ctrel0 = {
        .name           = "SYS_CTR_EL0",
        .ftr_bits       = ftr_ctr
};

static const struct arm64_ftr_bits ftr_id_mmfr0[] = {
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_INNERSHR_SHIFT, 4, 0xf),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_FCSE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_MMFR0_AUXREG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_TCM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_SHARELVL_SHIFT, 4, 0),
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_OUTERSHR_SHIFT, 4, 0xf),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_PMSA_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR0_VMSA_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = {
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_DOUBLELOCK_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR0_PMSVER_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_CTX_CMPS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_WRPS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_BRPS_SHIFT, 4, 0),
        /*
         * We can instantiate multiple PMU instances with different levels
         * of support.
         */
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64DFR0_PMUVER_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_TRACEVER_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_DEBUGVER_SHIFT, 4, 0x6),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_mvfr2[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, MVFR2_FPMISC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, MVFR2_SIMDMISC_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_dczid[] = {
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, DCZID_DZP_SHIFT, 1, 1),
        ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, DCZID_BS_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_isar0[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_DIVIDE_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_DEBUG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_COPROC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_CMPBRANCH_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_BITFIELD_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_BITCOUNT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR0_SWAP_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_isar5[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_RDM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_CRC32_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SHA2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SHA1_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_AES_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SEVL_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_mmfr4[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_EVT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_CCIDX_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_LSM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_HPDS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_CNP_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_XNX_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR4_AC2_SHIFT, 4, 0),

        /*
         * SpecSEI = 1 indicates that the PE might generate an SError on an
         * external abort on speculative read. It is safe to assume that an
         * SError might be generated than it will not be. Hence it has been
         * classified as FTR_HIGHER_SAFE.
         */
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_HIGHER_SAFE, ID_MMFR4_SPECSEI_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_isar4[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_SWP_FRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_PSR_M_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_SYNCH_PRIM_FRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_BARRIER_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_SMC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_WRITEBACK_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_WITHSHIFTS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR4_UNPRIV_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_mmfr5[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_MMFR5_ETS_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_isar6[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_I8MM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_BF16_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_SPECRES_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_SB_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_FHM_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_DP_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR6_JSCVT_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_pfr0[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_DIT_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR0_CSV2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_STATE3_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_STATE2_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_STATE1_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR0_STATE0_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_pfr1[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_GIC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_VIRT_FRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_SEC_FRAC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_GENTIMER_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_VIRTUALIZATION_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_MPROGMOD_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_SECURITY_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR1_PROGMOD_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_pfr2[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_SSBS_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_CSV3_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_dfr0[] = {
        /* [31:28] TraceFilt */
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_PERFMON_SHIFT, 4, 0xf),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_MPROFDBG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_MMAPTRC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_COPTRC_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_MMAPDBG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_COPSDBG_SHIFT, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR0_COPDBG_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_dfr1[] = {
        S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_DFR1_MTPMU_SHIFT, 4, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_zcr[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE,
                ZCR_ELx_LEN_SHIFT, ZCR_ELx_LEN_SIZE, 0),        /* LEN */
        ARM64_FTR_END,
};

/*
 * Common ftr bits for a 32bit register with all hidden, strict
 * attributes, with 4bit feature fields and a default safe value of
 * 0. Covers the following 32bit registers:
 * id_isar[1-4], id_mmfr[1-3], id_pfr1, mvfr[0-1]
 */
static const struct arm64_ftr_bits ftr_generic_32bits[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 24, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 20, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),
        ARM64_FTR_END,
};

/* Table for a single 32bit feature value */
static const struct arm64_ftr_bits ftr_single32[] = {
        ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, 0, 32, 0),
        ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_raz[] = {
        ARM64_FTR_END,
};

#define ARM64_FTR_REG(id, table) {              \
        .sys_id = id,                           \
        .reg =  &(struct arm64_ftr_reg){        \
                .name = #id,                    \
                .ftr_bits = &((table)[0]),      \
        }}

static const struct __ftr_reg_entry {
        u32                     sys_id;
        struct arm64_ftr_reg    *reg;
} arm64_ftr_regs[] = {

        /* Op1 = 0, CRn = 0, CRm = 1 */
        ARM64_FTR_REG(SYS_ID_PFR0_EL1, ftr_id_pfr0),
        ARM64_FTR_REG(SYS_ID_PFR1_EL1, ftr_id_pfr1),
        ARM64_FTR_REG(SYS_ID_DFR0_EL1, ftr_id_dfr0),
        ARM64_FTR_REG(SYS_ID_MMFR0_EL1, ftr_id_mmfr0),
        ARM64_FTR_REG(SYS_ID_MMFR1_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_ID_MMFR2_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_ID_MMFR3_EL1, ftr_generic_32bits),

        /* Op1 = 0, CRn = 0, CRm = 2 */
        ARM64_FTR_REG(SYS_ID_ISAR0_EL1, ftr_id_isar0),
        ARM64_FTR_REG(SYS_ID_ISAR1_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_ID_ISAR2_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_ID_ISAR3_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_ID_ISAR4_EL1, ftr_id_isar4),
        ARM64_FTR_REG(SYS_ID_ISAR5_EL1, ftr_id_isar5),
        ARM64_FTR_REG(SYS_ID_MMFR4_EL1, ftr_id_mmfr4),
        ARM64_FTR_REG(SYS_ID_ISAR6_EL1, ftr_id_isar6),

        /* Op1 = 0, CRn = 0, CRm = 3 */
        ARM64_FTR_REG(SYS_MVFR0_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_MVFR1_EL1, ftr_generic_32bits),
        ARM64_FTR_REG(SYS_MVFR2_EL1, ftr_mvfr2),
        ARM64_FTR_REG(SYS_ID_PFR2_EL1, ftr_id_pfr2),
        ARM64_FTR_REG(SYS_ID_DFR1_EL1, ftr_id_dfr1),
        ARM64_FTR_REG(SYS_ID_MMFR5_EL1, ftr_id_mmfr5),

        /* Op1 = 0, CRn = 0, CRm = 4 */
        ARM64_FTR_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0),
        ARM64_FTR_REG(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1),
        ARM64_FTR_REG(SYS_ID_AA64ZFR0_EL1, ftr_id_aa64zfr0),

        /* Op1 = 0, CRn = 0, CRm = 5 */
        ARM64_FTR_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0),
        ARM64_FTR_REG(SYS_ID_AA64DFR1_EL1, ftr_raz),

        /* Op1 = 0, CRn = 0, CRm = 6 */
        ARM64_FTR_REG(SYS_ID_AA64ISAR0_EL1, ftr_id_aa64isar0),
        ARM64_FTR_REG(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1),

        /* Op1 = 0, CRn = 0, CRm = 7 */
        ARM64_FTR_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0),
        ARM64_FTR_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1),
        ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),

        /* Op1 = 0, CRn = 1, CRm = 2 */
        ARM64_FTR_REG(SYS_ZCR_EL1, ftr_zcr),

        /* Op1 = 3, CRn = 0, CRm = 0 */
        { SYS_CTR_EL0, &arm64_ftr_reg_ctrel0 },
        ARM64_FTR_REG(SYS_DCZID_EL0, ftr_dczid),

        /* Op1 = 3, CRn = 14, CRm = 0 */
        ARM64_FTR_REG(SYS_CNTFRQ_EL0, ftr_single32),
};

static int search_cmp_ftr_reg(const void *id, const void *regp)
{
        return (int)(unsigned long)id - (int)((const struct __ftr_reg_entry *)regp)->sys_id;
}

/*
 * get_arm64_ftr_reg_nowarn - Looks up a feature register entry using
 * its sys_reg() encoding. With the array arm64_ftr_regs sorted in the
 * ascending order of sys_id, we use binary search to find a matching
 * entry.
 *
 * returns - Upon success,  matching ftr_reg entry for id.
 *         - NULL on failure. It is upto the caller to decide
 *           the impact of a failure.
 */
static struct arm64_ftr_reg *get_arm64_ftr_reg_nowarn(u32 sys_id)
{
        const struct __ftr_reg_entry *ret;

        ret = bsearch((const void *)(unsigned long)sys_id,
                        arm64_ftr_regs,
                        ARRAY_SIZE(arm64_ftr_regs),
                        sizeof(arm64_ftr_regs[0]),
                        search_cmp_ftr_reg);
        if (ret)
                return ret->reg;
        return NULL;
}

/*
 * get_arm64_ftr_reg - Looks up a feature register entry using
 * its sys_reg() encoding. This calls get_arm64_ftr_reg_nowarn().
 *
 * returns - Upon success,  matching ftr_reg entry for id.
 *         - NULL on failure but with an WARN_ON().
 */
static struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id)
{
        struct arm64_ftr_reg *reg;

        reg = get_arm64_ftr_reg_nowarn(sys_id);

        /*
         * Requesting a non-existent register search is an error. Warn
         * and let the caller handle it.
         */
        WARN_ON(!reg);
        return reg;
}

static u64 arm64_ftr_set_value(const struct arm64_ftr_bits *ftrp, s64 reg,
                               s64 ftr_val)
{
        u64 mask = arm64_ftr_mask(ftrp);

        reg &= ~mask;
        reg |= (ftr_val << ftrp->shift) & mask;
        return reg;
}

static s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new,
                                s64 cur)
{
        s64 ret = 0;

        switch (ftrp->type) {
        case FTR_EXACT:
                ret = ftrp->safe_val;
                break;
        case FTR_LOWER_SAFE:
                ret = new < cur ? new : cur;
                break;
        case FTR_HIGHER_OR_ZERO_SAFE:
                if (!cur || !new)
                        break;
                fallthrough;
        case FTR_HIGHER_SAFE:
                ret = new > cur ? new : cur;
                break;
        default:
                BUG();
        }

        return ret;
}

static void __init sort_ftr_regs(void)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(arm64_ftr_regs); i++) {
                const struct arm64_ftr_reg *ftr_reg = arm64_ftr_regs[i].reg;
                const struct arm64_ftr_bits *ftr_bits = ftr_reg->ftr_bits;
                unsigned int j = 0;

                /*
                 * Features here must be sorted in descending order with respect
                 * to their shift values and should not overlap with each other.
                 */
                for (; ftr_bits->width != 0; ftr_bits++, j++) {
                        unsigned int width = ftr_reg->ftr_bits[j].width;
                        unsigned int shift = ftr_reg->ftr_bits[j].shift;
                        unsigned int prev_shift;

                        WARN((shift  + width) > 64,
                                "%s has invalid feature at shift %d\n",
                                ftr_reg->name, shift);

                        /*
                         * Skip the first feature. There is nothing to
                         * compare against for now.
                         */
                        if (j == 0)
                                continue;

                        prev_shift = ftr_reg->ftr_bits[j - 1].shift;
                        WARN((shift + width) > prev_shift,
                                "%s has feature overlap at shift %d\n",
                                ftr_reg->name, shift);
                }

                /*
                 * Skip the first register. There is nothing to
                 * compare against for now.
                 */
                if (i == 0)
                        continue;
                /*
                 * Registers here must be sorted in ascending order with respect
                 * to sys_id for subsequent binary search in get_arm64_ftr_reg()
                 * to work correctly.
                 */
                BUG_ON(arm64_ftr_regs[i].sys_id < arm64_ftr_regs[i - 1].sys_id);
        }
}

/*
 * Initialise the CPU feature register from Boot CPU values.
 * Also initiliases the strict_mask for the register.
 * Any bits that are not covered by an arm64_ftr_bits entry are considered
 * RES0 for the system-wide value, and must strictly match.
 */
static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new)
{
        u64 val = 0;
        u64 strict_mask = ~0x0ULL;
        u64 user_mask = 0;
        u64 valid_mask = 0;

        const struct arm64_ftr_bits *ftrp;
        struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg);

        if (!reg)
                return;

        for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) {
                u64 ftr_mask = arm64_ftr_mask(ftrp);
                s64 ftr_new = arm64_ftr_value(ftrp, new);

                val = arm64_ftr_set_value(ftrp, val, ftr_new);

                valid_mask |= ftr_mask;
                if (!ftrp->strict)
                        strict_mask &= ~ftr_mask;
                if (ftrp->visible)
                        user_mask |= ftr_mask;
                else
                        reg->user_val = arm64_ftr_set_value(ftrp,
                                                            reg->user_val,
                                                            ftrp->safe_val);
        }

        val &= valid_mask;

        reg->sys_val = val;
        reg->strict_mask = strict_mask;
        reg->user_mask = user_mask;
}

extern const struct arm64_cpu_capabilities arm64_errata[];
static const struct arm64_cpu_capabilities arm64_features[];

static void __init
init_cpu_hwcaps_indirect_list_from_array(const struct arm64_cpu_capabilities *caps)
{
        for (; caps->matches; caps++) {
                if (WARN(caps->capability >= ARM64_NCAPS,
                        "Invalid capability %d\n", caps->capability))
                        continue;
                if (WARN(cpu_hwcaps_ptrs[caps->capability],
                        "Duplicate entry for capability %d\n",
                        caps->capability))
                        continue;
                cpu_hwcaps_ptrs[caps->capability] = caps;
        }
}

static void __init init_cpu_hwcaps_indirect_list(void)
{
        init_cpu_hwcaps_indirect_list_from_array(arm64_features);
        init_cpu_hwcaps_indirect_list_from_array(arm64_errata);
}

static void __init setup_boot_cpu_capabilities(void);

void __init init_cpu_features(struct cpuinfo_arm64 *info)
{
        /* Before we start using the tables, make sure it is sorted */
        sort_ftr_regs();

        init_cpu_ftr_reg(SYS_CTR_EL0, info->reg_ctr);
        init_cpu_ftr_reg(SYS_DCZID_EL0, info->reg_dczid);
        init_cpu_ftr_reg(SYS_CNTFRQ_EL0, info->reg_cntfrq);
        init_cpu_ftr_reg(SYS_ID_AA64DFR0_EL1, info->reg_id_aa64dfr0);
        init_cpu_ftr_reg(SYS_ID_AA64DFR1_EL1, info->reg_id_aa64dfr1);
        init_cpu_ftr_reg(SYS_ID_AA64ISAR0_EL1, info->reg_id_aa64isar0);
        init_cpu_ftr_reg(SYS_ID_AA64ISAR1_EL1, info->reg_id_aa64isar1);
        init_cpu_ftr_reg(SYS_ID_AA64MMFR0_EL1, info->reg_id_aa64mmfr0);
        init_cpu_ftr_reg(SYS_ID_AA64MMFR1_EL1, info->reg_id_aa64mmfr1);
        init_cpu_ftr_reg(SYS_ID_AA64MMFR2_EL1, info->reg_id_aa64mmfr2);
        init_cpu_ftr_reg(SYS_ID_AA64PFR0_EL1, info->reg_id_aa64pfr0);
        init_cpu_ftr_reg(SYS_ID_AA64PFR1_EL1, info->reg_id_aa64pfr1);
        init_cpu_ftr_reg(SYS_ID_AA64ZFR0_EL1, info->reg_id_aa64zfr0);

        if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0)) {
                init_cpu_ftr_reg(SYS_ID_DFR0_EL1, info->reg_id_dfr0);
                init_cpu_ftr_reg(SYS_ID_DFR1_EL1, info->reg_id_dfr1);
                init_cpu_ftr_reg(SYS_ID_ISAR0_EL1, info->reg_id_isar0);
                init_cpu_ftr_reg(SYS_ID_ISAR1_EL1, info->reg_id_isar1);
                init_cpu_ftr_reg(SYS_ID_ISAR2_EL1, info->reg_id_isar2);
                init_cpu_ftr_reg(SYS_ID_ISAR3_EL1, info->reg_id_isar3);
                init_cpu_ftr_reg(SYS_ID_ISAR4_EL1, info->reg_id_isar4);
                init_cpu_ftr_reg(SYS_ID_ISAR5_EL1, info->reg_id_isar5);
                init_cpu_ftr_reg(SYS_ID_ISAR6_EL1, info->reg_id_isar6);
                init_cpu_ftr_reg(SYS_ID_MMFR0_EL1, info->reg_id_mmfr0);
                init_cpu_ftr_reg(SYS_ID_MMFR1_EL1, info->reg_id_mmfr1);
                init_cpu_ftr_reg(SYS_ID_MMFR2_EL1, info->reg_id_mmfr2);
                init_cpu_ftr_reg(SYS_ID_MMFR3_EL1, info->reg_id_mmfr3);
                init_cpu_ftr_reg(SYS_ID_MMFR4_EL1, info->reg_id_mmfr4);
                init_cpu_ftr_reg(SYS_ID_MMFR5_EL1, info->reg_id_mmfr5);
                init_cpu_ftr_reg(SYS_ID_PFR0_EL1, info->reg_id_pfr0);
                init_cpu_ftr_reg(SYS_ID_PFR1_EL1, info->reg_id_pfr1);
                init_cpu_ftr_reg(SYS_ID_PFR2_EL1, info->reg_id_pfr2);
                init_cpu_ftr_reg(SYS_MVFR0_EL1, info->reg_mvfr0);
                init_cpu_ftr_reg(SYS_MVFR1_EL1, info->reg_mvfr1);
                init_cpu_ftr_reg(SYS_MVFR2_EL1, info->reg_mvfr2);
        }

        if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
                init_cpu_ftr_reg(SYS_ZCR_EL1, info->reg_zcr);
                sve_init_vq_map();
        }

        /*
         * Initialize the indirect array of CPU hwcaps capabilities pointers
         * before we handle the boot CPU below.
         */
        init_cpu_hwcaps_indirect_list();

        /*
         * Detect and enable early CPU capabilities based on the boot CPU,
         * after we have initialised the CPU feature infrastructure.
         */
        setup_boot_cpu_capabilities();
}

static void update_cpu_ftr_reg(struct arm64_ftr_reg *reg, u64 new)
{
        const struct arm64_ftr_bits *ftrp;

        for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) {
                s64 ftr_cur = arm64_ftr_value(ftrp, reg->sys_val);
                s64 ftr_new = arm64_ftr_value(ftrp, new);

                if (ftr_cur == ftr_new)
                        continue;
                /* Find a safe value */
                ftr_new = arm64_ftr_safe_value(ftrp, ftr_new, ftr_cur);
                reg->sys_val = arm64_ftr_set_value(ftrp, reg->sys_val, ftr_new);
        }

}

static int check_update_ftr_reg(u32 sys_id, int cpu, u64 val, u64 boot)
{
        struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id);

        if (!regp)
                return 0;

        update_cpu_ftr_reg(regp, val);
        if ((boot & regp->strict_mask) == (val & regp->strict_mask))
                return 0;
        pr_warn("SANITY CHECK: Unexpected variation in %s. Boot CPU: %#016llx, CPU%d: %#016llx\n",
                        regp->name, boot, cpu, val);
        return 1;
}

static void relax_cpu_ftr_reg(u32 sys_id, int field)
{
        const struct arm64_ftr_bits *ftrp;
        struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id);

        if (!regp)
                return;

        for (ftrp = regp->ftr_bits; ftrp->width; ftrp++) {
                if (ftrp->shift == field) {
                        regp->strict_mask &= ~arm64_ftr_mask(ftrp);
                        break;
                }
        }

        /* Bogus field? */
        WARN_ON(!ftrp->width);
}

static int update_32bit_cpu_features(int cpu, struct cpuinfo_arm64 *info,
                                     struct cpuinfo_arm64 *boot)
{
        int taint = 0;
        u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);

        /*
         * If we don't have AArch32 at all then skip the checks entirely
         * as the register values may be UNKNOWN and we're not going to be
         * using them for anything.
         */
        if (!id_aa64pfr0_32bit_el0(pfr0))
                return taint;

        /*
         * If we don't have AArch32 at EL1, then relax the strictness of
         * EL1-dependent register fields to avoid spurious sanity check fails.
         */
        if (!id_aa64pfr0_32bit_el1(pfr0)) {
                relax_cpu_ftr_reg(SYS_ID_ISAR4_EL1, ID_ISAR4_SMC_SHIFT);
                relax_cpu_ftr_reg(SYS_ID_PFR1_EL1, ID_PFR1_VIRT_FRAC_SHIFT);
                relax_cpu_ftr_reg(SYS_ID_PFR1_EL1, ID_PFR1_SEC_FRAC_SHIFT);
                relax_cpu_ftr_reg(SYS_ID_PFR1_EL1, ID_PFR1_VIRTUALIZATION_SHIFT);
                relax_cpu_ftr_reg(SYS_ID_PFR1_EL1, ID_PFR1_SECURITY_SHIFT);
                relax_cpu_ftr_reg(SYS_ID_PFR1_EL1, ID_PFR1_PROGMOD_SHIFT);
        }

        taint |= check_update_ftr_reg(SYS_ID_DFR0_EL1, cpu,
                                      info->reg_id_dfr0, boot->reg_id_dfr0);
        taint |= check_update_ftr_reg(SYS_ID_DFR1_EL1, cpu,
                                      info->reg_id_dfr1, boot->reg_id_dfr1);
        taint |= check_update_ftr_reg(SYS_ID_ISAR0_EL1, cpu,
                                      info->reg_id_isar0, boot->reg_id_isar0);
        taint |= check_update_ftr_reg(SYS_ID_ISAR1_EL1, cpu,
                                      info->reg_id_isar1, boot->reg_id_isar1);
        taint |= check_update_ftr_reg(SYS_ID_ISAR2_EL1, cpu,
                                      info->reg_id_isar2, boot->reg_id_isar2);
        taint |= check_update_ftr_reg(SYS_ID_ISAR3_EL1, cpu,
                                      info->reg_id_isar3, boot->reg_id_isar3);
        taint |= check_update_ftr_reg(SYS_ID_ISAR4_EL1, cpu,
                                      info->reg_id_isar4, boot->reg_id_isar4);
        taint |= check_update_ftr_reg(SYS_ID_ISAR5_EL1, cpu,
                                      info->reg_id_isar5, boot->reg_id_isar5);
        taint |= check_update_ftr_reg(SYS_ID_ISAR6_EL1, cpu,
                                      info->reg_id_isar6, boot->reg_id_isar6);

        /*
         * Regardless of the value of the AuxReg field, the AIFSR, ADFSR, and
         * ACTLR formats could differ across CPUs and therefore would have to
         * be trapped for virtualization anyway.
         */
        taint |= check_update_ftr_reg(SYS_ID_MMFR0_EL1, cpu,
                                      info->reg_id_mmfr0, boot->reg_id_mmfr0);
        taint |= check_update_ftr_reg(SYS_ID_MMFR1_EL1, cpu,
                                      info->reg_id_mmfr1, boot->reg_id_mmfr1);
        taint |= check_update_ftr_reg(SYS_ID_MMFR2_EL1, cpu,
                                      info->reg_id_mmfr2, boot->reg_id_mmfr2);
        taint |= check_update_ftr_reg(SYS_ID_MMFR3_EL1, cpu,
                                      info->reg_id_mmfr3, boot->reg_id_mmfr3);
        taint |= check_update_ftr_reg(SYS_ID_MMFR4_EL1, cpu,
                                      info->reg_id_mmfr4, boot->reg_id_mmfr4);
        taint |= check_update_ftr_reg(SYS_ID_MMFR5_EL1, cpu,
                                      info->reg_id_mmfr5, boot->reg_id_mmfr5);
        taint |= check_update_ftr_reg(SYS_ID_PFR0_EL1, cpu,
                                      info->reg_id_pfr0, boot->reg_id_pfr0);
        taint |= check_update_ftr_reg(SYS_ID_PFR1_EL1, cpu,
                                      info->reg_id_pfr1, boot->reg_id_pfr1);
        taint |= check_update_ftr_reg(SYS_ID_PFR2_EL1, cpu,
                                      info->reg_id_pfr2, boot->reg_id_pfr2);
        taint |= check_update_ftr_reg(SYS_MVFR0_EL1, cpu,
                                      info->reg_mvfr0, boot->reg_mvfr0);
        taint |= check_update_ftr_reg(SYS_MVFR1_EL1, cpu,
                                      info->reg_mvfr1, boot->reg_mvfr1);
        taint |= check_update_ftr_reg(SYS_MVFR2_EL1, cpu,
                                      info->reg_mvfr2, boot->reg_mvfr2);

        return taint;
}

/*
 * Update system wide CPU feature registers with the values from a
 * non-boot CPU. Also performs SANITY checks to make sure that there
 * aren't any insane variations from that of the boot CPU.
 */
void update_cpu_features(int cpu,
                         struct cpuinfo_arm64 *info,
                         struct cpuinfo_arm64 *boot)
{
        int taint = 0;

        /*
         * The kernel can handle differing I-cache policies, but otherwise
         * caches should look identical. Userspace JITs will make use of
         * *minLine.
         */
        taint |= check_update_ftr_reg(SYS_CTR_EL0, cpu,
                                      info->reg_ctr, boot->reg_ctr);

        /*
         * Userspace may perform DC ZVA instructions. Mismatched block sizes
         * could result in too much or too little memory being zeroed if a
         * process is preempted and migrated between CPUs.
         */
        taint |= check_update_ftr_reg(SYS_DCZID_EL0, cpu,
                                      info->reg_dczid, boot->reg_dczid);

        /* If different, timekeeping will be broken (especially with KVM) */
        taint |= check_update_ftr_reg(SYS_CNTFRQ_EL0, cpu,
                                      info->reg_cntfrq, boot->reg_cntfrq);

        /*
         * The kernel uses self-hosted debug features and expects CPUs to
         * support identical debug features. We presently need CTX_CMPs, WRPs,
         * and BRPs to be identical.
         * ID_AA64DFR1 is currently RES0.
         */
        taint |= check_update_ftr_reg(SYS_ID_AA64DFR0_EL1, cpu,
                                      info->reg_id_aa64dfr0, boot->reg_id_aa64dfr0);
        taint |= check_update_ftr_reg(SYS_ID_AA64DFR1_EL1, cpu,
                                      info->reg_id_aa64dfr1, boot->reg_id_aa64dfr1);
        /*
         * Even in big.LITTLE, processors should be identical instruction-set
         * wise.
         */
        taint |= check_update_ftr_reg(SYS_ID_AA64ISAR0_EL1, cpu,
                                      info->reg_id_aa64isar0, boot->reg_id_aa64isar0);
        taint |= check_update_ftr_reg(SYS_ID_AA64ISAR1_EL1, cpu,
                                      info->reg_id_aa64isar1, boot->reg_id_aa64isar1);

        /*
         * Differing PARange support is fine as long as all peripherals and
         * memory are mapped within the minimum PARange of all CPUs.
         * Linux should not care about secure memory.
         */
        taint |= check_update_ftr_reg(SYS_ID_AA64MMFR0_EL1, cpu,
                                      info->reg_id_aa64mmfr0, boot->reg_id_aa64mmfr0);
        taint |= check_update_ftr_reg(SYS_ID_AA64MMFR1_EL1, cpu,
                                      info->reg_id_aa64mmfr1, boot->reg_id_aa64mmfr1);
        taint |= check_update_ftr_reg(SYS_ID_AA64MMFR2_EL1, cpu,
                                      info->reg_id_aa64mmfr2, boot->reg_id_aa64mmfr2);

        taint |= check_update_ftr_reg(SYS_ID_AA64PFR0_EL1, cpu,
                                      info->reg_id_aa64pfr0, boot->reg_id_aa64pfr0);
        taint |= check_update_ftr_reg(SYS_ID_AA64PFR1_EL1, cpu,
                                      info->reg_id_aa64pfr1, boot->reg_id_aa64pfr1);

        taint |= check_update_ftr_reg(SYS_ID_AA64ZFR0_EL1, cpu,
                                      info->reg_id_aa64zfr0, boot->reg_id_aa64zfr0);

        if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
                taint |= check_update_ftr_reg(SYS_ZCR_EL1, cpu,
                                        info->reg_zcr, boot->reg_zcr);

                /* Probe vector lengths, unless we already gave up on SVE */
                if (id_aa64pfr0_sve(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1)) &&
                    !system_capabilities_finalized())
                        sve_update_vq_map();
        }

        /*
         * This relies on a sanitised view of the AArch64 ID registers
         * (e.g. SYS_ID_AA64PFR0_EL1), so we call it last.
         */
        taint |= update_32bit_cpu_features(cpu, info, boot);

        /*
         * Mismatched CPU features are a recipe for disaster. Don't even
         * pretend to support them.
         */
        if (taint) {
                pr_warn_once("Unsupported CPU feature variation detected.\n");
                add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
        }
}

u64 read_sanitised_ftr_reg(u32 id)
{
        struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);

        if (!regp)
                return 0;
        return regp->sys_val;
}

#define read_sysreg_case(r)     \
        case r:         return read_sysreg_s(r)

/*
 * __read_sysreg_by_encoding() - Used by a STARTING cpu before cpuinfo is populated.
 * Read the system register on the current CPU
 */
static u64 __read_sysreg_by_encoding(u32 sys_id)
{
        switch (sys_id) {
        read_sysreg_case(SYS_ID_PFR0_EL1);
        read_sysreg_case(SYS_ID_PFR1_EL1);
        read_sysreg_case(SYS_ID_PFR2_EL1);
        read_sysreg_case(SYS_ID_DFR0_EL1);
        read_sysreg_case(SYS_ID_DFR1_EL1);
        read_sysreg_case(SYS_ID_MMFR0_EL1);
        read_sysreg_case(SYS_ID_MMFR1_EL1);
        read_sysreg_case(SYS_ID_MMFR2_EL1);
        read_sysreg_case(SYS_ID_MMFR3_EL1);
        read_sysreg_case(SYS_ID_MMFR4_EL1);
        read_sysreg_case(SYS_ID_MMFR5_EL1);
        read_sysreg_case(SYS_ID_ISAR0_EL1);
        read_sysreg_case(SYS_ID_ISAR1_EL1);
        read_sysreg_case(SYS_ID_ISAR2_EL1);
        read_sysreg_case(SYS_ID_ISAR3_EL1);
        read_sysreg_case(SYS_ID_ISAR4_EL1);
        read_sysreg_case(SYS_ID_ISAR5_EL1);
        read_sysreg_case(SYS_ID_ISAR6_EL1);
        read_sysreg_case(SYS_MVFR0_EL1);
        read_sysreg_case(SYS_MVFR1_EL1);
        read_sysreg_case(SYS_MVFR2_EL1);

        read_sysreg_case(SYS_ID_AA64PFR0_EL1);
        read_sysreg_case(SYS_ID_AA64PFR1_EL1);
        read_sysreg_case(SYS_ID_AA64ZFR0_EL1);
        read_sysreg_case(SYS_ID_AA64DFR0_EL1);
        read_sysreg_case(SYS_ID_AA64DFR1_EL1);
        read_sysreg_case(SYS_ID_AA64MMFR0_EL1);
        read_sysreg_case(SYS_ID_AA64MMFR1_EL1);
        read_sysreg_case(SYS_ID_AA64MMFR2_EL1);
        read_sysreg_case(SYS_ID_AA64ISAR0_EL1);
        read_sysreg_case(SYS_ID_AA64ISAR1_EL1);

        read_sysreg_case(SYS_CNTFRQ_EL0);
        read_sysreg_case(SYS_CTR_EL0);
        read_sysreg_case(SYS_DCZID_EL0);

        default:
                BUG();
                return 0;
        }
}

#include <linux/irqchip/arm-gic-v3.h>

static bool
feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
{
        int val = cpuid_feature_extract_field(reg, entry->field_pos, entry->sign);

        return val >= entry->min_field_value;
}

static bool
has_cpuid_feature(const struct arm64_cpu_capabilities *entry, int scope)
{
        u64 val;

        WARN_ON(scope == SCOPE_LOCAL_CPU && preemptible());
        if (scope == SCOPE_SYSTEM)
                val = read_sanitised_ftr_reg(entry->sys_reg);
        else
                val = __read_sysreg_by_encoding(entry->sys_reg);

        return feature_matches(val, entry);
}

static bool has_useable_gicv3_cpuif(const struct arm64_cpu_capabilities *entry, int scope)
{
        bool has_sre;

        if (!has_cpuid_feature(entry, scope))
                return false;

        has_sre = gic_enable_sre();
        if (!has_sre)
                pr_warn_once("%s present but disabled by higher exception level\n",
                             entry->desc);

        return has_sre;
}

static bool has_no_hw_prefetch(const struct arm64_cpu_capabilities *entry, int __unused)
{
        u32 midr = read_cpuid_id();

        /* Cavium ThunderX pass 1.x and 2.x */
        return midr_is_cpu_model_range(midr, MIDR_THUNDERX,
                MIDR_CPU_VAR_REV(0, 0),
                MIDR_CPU_VAR_REV(1, MIDR_REVISION_MASK));
}

static bool has_no_fpsimd(const struct arm64_cpu_capabilities *entry, int __unused)
{
        u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);

        return cpuid_feature_extract_signed_field(pfr0,
                                        ID_AA64PFR0_FP_SHIFT) < 0;
}

static bool has_cache_idc(const struct arm64_cpu_capabilities *entry,
                          int scope)
{
        u64 ctr;

        if (scope == SCOPE_SYSTEM)
                ctr = arm64_ftr_reg_ctrel0.sys_val;
        else
                ctr = read_cpuid_effective_cachetype();

        return ctr & BIT(CTR_IDC_SHIFT);
}

static void cpu_emulate_effective_ctr(const struct arm64_cpu_capabilities *__unused)
{
        /*
         * If the CPU exposes raw CTR_EL0.IDC = 0, while effectively
         * CTR_EL0.IDC = 1 (from CLIDR values), we need to trap accesses
         * to the CTR_EL0 on this CPU and emulate it with the real/safe
         * value.
         */
        if (!(read_cpuid_cachetype() & BIT(CTR_IDC_SHIFT)))
                sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0);
}

static bool has_cache_dic(const struct arm64_cpu_capabilities *entry,
                          int scope)
{
        u64 ctr;

        if (scope == SCOPE_SYSTEM)
                ctr = arm64_ftr_reg_ctrel0.sys_val;
        else
                ctr = read_cpuid_cachetype();

        return ctr & BIT(CTR_DIC_SHIFT);
}

static bool __maybe_unused
has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
{
        /*
         * Kdump isn't guaranteed to power-off all secondary CPUs, CNP
         * may share TLB entries with a CPU stuck in the crashed
         * kernel.
         */
         if (is_kdump_kernel())
                return false;

        return has_cpuid_feature(entry, scope);
}

/*
 * This check is triggered during the early boot before the cpufeature
 * is initialised. Checking the status on the local CPU allows the boot
 * CPU to detect the need for non-global mappings and thus avoiding a
 * pagetable re-write after all the CPUs are booted. This check will be
 * anyway run on individual CPUs, allowing us to get the consistent
 * state once the SMP CPUs are up and thus make the switch to non-global
 * mappings if required.
 */
bool kaslr_requires_kpti(void)
{
        if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
                return false;

        /*
         * E0PD does a similar job to KPTI so can be used instead
         * where available.
         */
        if (IS_ENABLED(CONFIG_ARM64_E0PD)) {
                u64 mmfr2 = read_sysreg_s(SYS_ID_AA64MMFR2_EL1);
                if (cpuid_feature_extract_unsigned_field(mmfr2,
                                                ID_AA64MMFR2_E0PD_SHIFT))
                        return false;
        }

        /*
         * Systems affected by Cavium erratum 24756 are incompatible
         * with KPTI.
         */
        if (IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
                extern const struct midr_range cavium_erratum_27456_cpus[];

                if (is_midr_in_range_list(read_cpuid_id(),
                                          cavium_erratum_27456_cpus))
                        return false;
        }

        return kaslr_offset() > 0;
}

static bool __meltdown_safe = true;
static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */

static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
                                int scope)
{
        /* List of CPUs that are not vulnerable and don't need KPTI */
        static const struct midr_range kpti_safe_list[] = {
                MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
                MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
                MIDR_ALL_VERSIONS(MIDR_BRAHMA_B53),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A35),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A53),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
                MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
                MIDR_ALL_VERSIONS(MIDR_HISI_TSV110),
                MIDR_ALL_VERSIONS(MIDR_NVIDIA_CARMEL),
                MIDR_ALL_VERSIONS(MIDR_QCOM_KRYO_3XX_SILVER),
                MIDR_ALL_VERSIONS(MIDR_QCOM_KRYO_4XX_SILVER),
                { /* sentinel */ }
        };
        char const *str = "kpti command line option";
        bool meltdown_safe;

        meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list);

        /* Defer to CPU feature registers */
        if (has_cpuid_feature(entry, scope))
                meltdown_safe = true;

        if (!meltdown_safe)
                __meltdown_safe = false;

        /*
         * For reasons that aren't entirely clear, enabling KPTI on Cavium
         * ThunderX leads to apparent I-cache corruption of kernel text, which
         * ends as well as you might imagine. Don't even try.
         */
        if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456)) {
                str = "ARM64_WORKAROUND_CAVIUM_27456";
                __kpti_forced = -1;
        }

        /* Useful for KASLR robustness */
        if (kaslr_requires_kpti()) {
                if (!__kpti_forced) {
                        str = "KASLR";
                        __kpti_forced = 1;
                }
        }

        if (cpu_mitigations_off() && !__kpti_forced) {
                str = "mitigations=off";
                __kpti_forced = -1;
        }

        if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) {
                pr_info_once("kernel page table isolation disabled by kernel configuration\n");
                return false;
        }

        /* Forced? */
        if (__kpti_forced) {
                pr_info_once("kernel page table isolation forced %s by %s\n",
                             __kpti_forced > 0 ? "ON" : "OFF", str);
                return __kpti_forced > 0;
        }

        return !meltdown_safe;
}

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
static void
kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
{
        typedef void (kpti_remap_fn)(int, int, phys_addr_t);
        extern kpti_remap_fn idmap_kpti_install_ng_mappings;
        kpti_remap_fn *remap_fn;

        int cpu = smp_processor_id();

        /*
         * We don't need to rewrite the page-tables if either we've done
         * it already or we have KASLR enabled and therefore have not
         * created any global mappings at all.
         */
        if (arm64_use_ng_mappings)
                return;

        remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);

        cpu_install_idmap();
        remap_fn(cpu, num_online_cpus(), __pa_symbol(swapper_pg_dir));
        cpu_uninstall_idmap();

        if (!cpu)
                arm64_use_ng_mappings = true;

        return;
}
#else
static void
kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
{
}
#endif  /* CONFIG_UNMAP_KERNEL_AT_EL0 */

static int __init parse_kpti(char *str)
{
        bool enabled;
        int ret = strtobool(str, &enabled);

        if (ret)
                return ret;

        __kpti_forced = enabled ? 1 : -1;
        return 0;
}
early_param("kpti", parse_kpti);

#ifdef CONFIG_ARM64_HW_AFDBM
static inline void __cpu_enable_hw_dbm(void)
{
        u64 tcr = read_sysreg(tcr_el1) | TCR_HD;

        write_sysreg(tcr, tcr_el1);
        isb();
}

static bool cpu_has_broken_dbm(void)
{
        /* List of CPUs which have broken DBM support. */
        static const struct midr_range cpus[] = {
#ifdef CONFIG_ARM64_ERRATUM_1024718
                MIDR_RANGE(MIDR_CORTEX_A55, 0, 0, 1, 0),  // A55 r0p0 -r1p0
                /* Kryo4xx Silver (rdpe => r1p0) */
                MIDR_REV(MIDR_QCOM_KRYO_4XX_SILVER, 0xd, 0xe),
#endif
                {},
        };

        return is_midr_in_range_list(read_cpuid_id(), cpus);
}

static bool cpu_can_use_dbm(const struct arm64_cpu_capabilities *cap)
{
        return has_cpuid_feature(cap, SCOPE_LOCAL_CPU) &&
               !cpu_has_broken_dbm();
}

static void cpu_enable_hw_dbm(struct arm64_cpu_capabilities const *cap)
{
        if (cpu_can_use_dbm(cap))
                __cpu_enable_hw_dbm();
}

static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
                       int __unused)
{
        static bool detected = false;
        /*
         * DBM is a non-conflicting feature. i.e, the kernel can safely
         * run a mix of CPUs with and without the feature. So, we
         * unconditionally enable the capability to allow any late CPU
         * to use the feature. We only enable the control bits on the
         * CPU, if it actually supports.
         *
         * We have to make sure we print the "feature" detection only
         * when at least one CPU actually uses it. So check if this CPU
         * can actually use it and print the message exactly once.
         *
         * This is safe as all CPUs (including secondary CPUs - due to the
         * LOCAL_CPU scope - and the hotplugged CPUs - via verification)
         * goes through the "matches" check exactly once. Also if a CPU
         * matches the criteria, it is guaranteed that the CPU will turn
         * the DBM on, as the capability is unconditionally enabled.
         */
        if (!detected && cpu_can_use_dbm(cap)) {
                detected = true;
                pr_info("detected: Hardware dirty bit management\n");
        }

        return true;
}

#endif

#ifdef CONFIG_ARM64_AMU_EXTN

/*
 * The "amu_cpus" cpumask only signals that the CPU implementation for the
 * flagged CPUs supports the Activity Monitors Unit (AMU) but does not provide
 * information regarding all the events that it supports. When a CPU bit is
 * set in the cpumask, the user of this feature can only rely on the presence
 * of the 4 fixed counters for that CPU. But this does not guarantee that the
 * counters are enabled or access to these counters is enabled by code
 * executed at higher exception levels (firmware).
 */
static struct cpumask amu_cpus __read_mostly;

bool cpu_has_amu_feat(int cpu)
{
        return cpumask_test_cpu(cpu, &amu_cpus);
}

/* Initialize the use of AMU counters for frequency invariance */
extern void init_cpu_freq_invariance_counters(void);

static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap)
{
        if (has_cpuid_feature(cap, SCOPE_LOCAL_CPU)) {
                pr_info("detected CPU%d: Activity Monitors Unit (AMU)\n",
                        smp_processor_id());
                cpumask_set_cpu(smp_processor_id(), &amu_cpus);
                init_cpu_freq_invariance_counters();
        }
}

static bool has_amu(const struct arm64_cpu_capabilities *cap,
                    int __unused)
{
        /*
         * The AMU extension is a non-conflicting feature: the kernel can
         * safely run a mix of CPUs with and without support for the
         * activity monitors extension. Therefore, unconditionally enable
         * the capability to allow any late CPU to use the feature.
         *
         * With this feature unconditionally enabled, the cpu_enable
         * function will be called for all CPUs that match the criteria,
         * including secondary and hotplugged, marking this feature as
         * present on that respective CPU. The enable function will also
         * print a detection message.
         */

        return true;
}
#endif

#ifdef CONFIG_ARM64_VHE
static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused)
{
        return is_kernel_in_hyp_mode();
}

static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
{
        /*
         * Copy register values that aren't redirected by hardware.
         *
         * Before code patching, we only set tpidr_el1, all CPUs need to copy
         * this value to tpidr_el2 before we patch the code. Once we've done
         * that, freshly-onlined CPUs will set tpidr_el2, so we don't need to
         * do anything here.
         */
        if (!alternative_is_applied(ARM64_HAS_VIRT_HOST_EXTN))
                write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
}
#endif

static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused)
{
        u64 val = read_sysreg_s(SYS_CLIDR_EL1);

        /* Check that CLIDR_EL1.LOU{U,IS} are both 0 */
        WARN_ON(val & (7 << 27 | 7 << 21));
}

#ifdef CONFIG_ARM64_PAN
static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused)
{
        /*
         * We modify PSTATE. This won't work from irq context as the PSTATE
         * is discarded once we return from the exception.
         */
        WARN_ON_ONCE(in_interrupt());

        sysreg_clear_set(sctlr_el1, SCTLR_EL1_SPAN, 0);
        asm(SET_PSTATE_PAN(1));
}
#endif /* CONFIG_ARM64_PAN */

#ifdef CONFIG_ARM64_RAS_EXTN
static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
{
        /* Firmware may have left a deferred SError in this register. */
        write_sysreg_s(0, SYS_DISR_EL1);
}
#endif /* CONFIG_ARM64_RAS_EXTN */

#ifdef CONFIG_ARM64_PTR_AUTH
static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
                             int __unused)
{
        return __system_matches_cap(ARM64_HAS_ADDRESS_AUTH_ARCH) ||
               __system_matches_cap(ARM64_HAS_ADDRESS_AUTH_IMP_DEF);
}

static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
                             int __unused)
{
        return __system_matches_cap(ARM64_HAS_GENERIC_AUTH_ARCH) ||
               __system_matches_cap(ARM64_HAS_GENERIC_AUTH_IMP_DEF);
}
#endif /* CONFIG_ARM64_PTR_AUTH */

#ifdef CONFIG_ARM64_E0PD
static void cpu_enable_e0pd(struct arm64_cpu_capabilities const *cap)
{
        if (this_cpu_has_cap(ARM64_HAS_E0PD))
                sysreg_clear_set(tcr_el1, 0, TCR_E0PD1);
}
#endif /* CONFIG_ARM64_E0PD */

#ifdef CONFIG_ARM64_PSEUDO_NMI
static bool enable_pseudo_nmi;

static int __init early_enable_pseudo_nmi(char *p)
{
        return strtobool(p, &enable_pseudo_nmi);
}
early_param("irqchip.gicv3_pseudo_nmi", early_enable_pseudo_nmi);

static bool can_use_gic_priorities(const struct arm64_cpu_capabilities *entry,
                                   int scope)
{
        return enable_pseudo_nmi && has_useable_gicv3_cpuif(entry, scope);
}
#endif

#ifdef CONFIG_ARM64_BTI
static void bti_enable(const struct arm64_cpu_capabilities *__unused)
{
        /*
         * Use of X16/X17 for tail-calls and trampolines that jump to
         * function entry points using BR is a requirement for
         * marking binaries with GNU_PROPERTY_AARCH64_FEATURE_1_BTI.
         * So, be strict and forbid other BRs using other registers to
         * jump onto a PACIxSP instruction:
         */
        sysreg_clear_set(sctlr_el1, 0, SCTLR_EL1_BT0 | SCTLR_EL1_BT1);
        isb();
}
#endif /* CONFIG_ARM64_BTI */

/* Internal helper functions to match cpu capability type */
static bool
cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap)
{
        return !!(cap->type & ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU);
}

static bool
cpucap_late_cpu_permitted(const struct arm64_cpu_capabilities *cap)
{
        return !!(cap->type & ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU);
}

static bool
cpucap_panic_on_conflict(const struct arm64_cpu_capabilities *cap)
{
        return !!(cap->type & ARM64_CPUCAP_PANIC_ON_CONFLICT);
}

static const struct arm64_cpu_capabilities arm64_features[] = {
        {
                .desc = "GIC system register CPU interface",
                .capability = ARM64_HAS_SYSREG_GIC_CPUIF,
                .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
                .matches = has_useable_gicv3_cpuif,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .field_pos = ID_AA64PFR0_GIC_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
        },
#ifdef CONFIG_ARM64_PAN
        {
                .desc = "Privileged Access Never",
                .capability = ARM64_HAS_PAN,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64MMFR1_EL1,
                .field_pos = ID_AA64MMFR1_PAN_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
                .cpu_enable = cpu_enable_pan,
        },
#endif /* CONFIG_ARM64_PAN */
#ifdef CONFIG_ARM64_LSE_ATOMICS
        {
                .desc = "LSE atomic instructions",
                .capability = ARM64_HAS_LSE_ATOMICS,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR0_EL1,
                .field_pos = ID_AA64ISAR0_ATOMICS_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 2,
        },
#endif /* CONFIG_ARM64_LSE_ATOMICS */
        {
                .desc = "Software prefetching using PRFM",
                .capability = ARM64_HAS_NO_HW_PREFETCH,
                .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
                .matches = has_no_hw_prefetch,
        },
#ifdef CONFIG_ARM64_UAO
        {
                .desc = "User Access Override",
                .capability = ARM64_HAS_UAO,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64MMFR2_EL1,
                .field_pos = ID_AA64MMFR2_UAO_SHIFT,
                .min_field_value = 1,
                /*
                 * We rely on stop_machine() calling uao_thread_switch() to set
                 * UAO immediately after patching.
                 */
        },
#endif /* CONFIG_ARM64_UAO */
#ifdef CONFIG_ARM64_PAN
        {
                .capability = ARM64_ALT_PAN_NOT_UAO,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = cpufeature_pan_not_uao,
        },
#endif /* CONFIG_ARM64_PAN */
#ifdef CONFIG_ARM64_VHE
        {
                .desc = "Virtualization Host Extensions",
                .capability = ARM64_HAS_VIRT_HOST_EXTN,
                .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
                .matches = runs_at_el2,
                .cpu_enable = cpu_copy_el2regs,
        },
#endif  /* CONFIG_ARM64_VHE */
        {
                .desc = "32-bit EL0 Support",
                .capability = ARM64_HAS_32BIT_EL0,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64PFR0_EL0_SHIFT,
                .min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
        },
#ifdef CONFIG_KVM
        {
                .desc = "32-bit EL1 Support",
                .capability = ARM64_HAS_32BIT_EL1,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64PFR0_EL1_SHIFT,
                .min_field_value = ID_AA64PFR0_EL1_32BIT_64BIT,
        },
#endif
        {
                .desc = "Kernel page table isolation (KPTI)",
                .capability = ARM64_UNMAP_KERNEL_AT_EL0,
                .type = ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE,
                /*
                 * The ID feature fields below are used to indicate that
                 * the CPU doesn't need KPTI. See unmap_kernel_at_el0 for
                 * more details.
                 */
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .field_pos = ID_AA64PFR0_CSV3_SHIFT,
                .min_field_value = 1,
                .matches = unmap_kernel_at_el0,
                .cpu_enable = kpti_install_ng_mappings,
        },
        {
                /* FP/SIMD is not implemented */
                .capability = ARM64_HAS_NO_FPSIMD,
                .type = ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE,
                .min_field_value = 0,
                .matches = has_no_fpsimd,
        },
#ifdef CONFIG_ARM64_PMEM
        {
                .desc = "Data cache clean to Point of Persistence",
                .capability = ARM64_HAS_DCPOP,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .field_pos = ID_AA64ISAR1_DPB_SHIFT,
                .min_field_value = 1,
        },
        {
                .desc = "Data cache clean to Point of Deep Persistence",
                .capability = ARM64_HAS_DCPODP,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64ISAR1_DPB_SHIFT,
                .min_field_value = 2,
        },
#endif
#ifdef CONFIG_ARM64_SVE
        {
                .desc = "Scalable Vector Extension",
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .capability = ARM64_SVE,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64PFR0_SVE_SHIFT,
                .min_field_value = ID_AA64PFR0_SVE,
                .matches = has_cpuid_feature,
                .cpu_enable = sve_kernel_enable,
        },
#endif /* CONFIG_ARM64_SVE */
#ifdef CONFIG_ARM64_RAS_EXTN
        {
                .desc = "RAS Extension Support",
                .capability = ARM64_HAS_RAS_EXTN,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64PFR0_RAS_SHIFT,
                .min_field_value = ID_AA64PFR0_RAS_V1,
                .cpu_enable = cpu_clear_disr,
        },
#endif /* CONFIG_ARM64_RAS_EXTN */
#ifdef CONFIG_ARM64_AMU_EXTN
        {
                /*
                 * The feature is enabled by default if CONFIG_ARM64_AMU_EXTN=y.
                 * Therefore, don't provide .desc as we don't want the detection
                 * message to be shown until at least one CPU is detected to
                 * support the feature.
                 */
                .capability = ARM64_HAS_AMU_EXTN,
                .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
                .matches = has_amu,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64PFR0_AMU_SHIFT,
                .min_field_value = ID_AA64PFR0_AMU,
                .cpu_enable = cpu_amu_enable,
        },
#endif /* CONFIG_ARM64_AMU_EXTN */
        {
                .desc = "Data cache clean to the PoU not required for I/D coherence",
                .capability = ARM64_HAS_CACHE_IDC,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cache_idc,
                .cpu_enable = cpu_emulate_effective_ctr,
        },
        {
                .desc = "Instruction cache invalidation not required for I/D coherence",
                .capability = ARM64_HAS_CACHE_DIC,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cache_dic,
        },
        {
                .desc = "Stage-2 Force Write-Back",
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .capability = ARM64_HAS_STAGE2_FWB,
                .sys_reg = SYS_ID_AA64MMFR2_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64MMFR2_FWB_SHIFT,
                .min_field_value = 1,
                .matches = has_cpuid_feature,
                .cpu_enable = cpu_has_fwb,
        },
        {
                .desc = "ARMv8.4 Translation Table Level",
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .capability = ARM64_HAS_ARMv8_4_TTL,
                .sys_reg = SYS_ID_AA64MMFR2_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64MMFR2_TTL_SHIFT,
                .min_field_value = 1,
                .matches = has_cpuid_feature,
        },
        {
                .desc = "TLB range maintenance instructions",
                .capability = ARM64_HAS_TLB_RANGE,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR0_EL1,
                .field_pos = ID_AA64ISAR0_TLB_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = ID_AA64ISAR0_TLB_RANGE,
        },
#ifdef CONFIG_ARM64_HW_AFDBM
        {
                /*
                 * Since we turn this on always, we don't want the user to
                 * think that the feature is available when it may not be.
                 * So hide the description.
                 *
                 * .desc = "Hardware pagetable Dirty Bit Management",
                 *
                 */
                .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
                .capability = ARM64_HW_DBM,
                .sys_reg = SYS_ID_AA64MMFR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64MMFR1_HADBS_SHIFT,
                .min_field_value = 2,
                .matches = has_hw_dbm,
                .cpu_enable = cpu_enable_hw_dbm,
        },
#endif
        {
                .desc = "CRC32 instructions",
                .capability = ARM64_HAS_CRC32,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR0_EL1,
                .field_pos = ID_AA64ISAR0_CRC32_SHIFT,
                .min_field_value = 1,
        },
        {
                .desc = "Speculative Store Bypassing Safe (SSBS)",
                .capability = ARM64_SSBS,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64PFR1_EL1,
                .field_pos = ID_AA64PFR1_SSBS_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = ID_AA64PFR1_SSBS_PSTATE_ONLY,
        },
#ifdef CONFIG_ARM64_CNP
        {
                .desc = "Common not Private translations",
                .capability = ARM64_HAS_CNP,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_useable_cnp,
                .sys_reg = SYS_ID_AA64MMFR2_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64MMFR2_CNP_SHIFT,
                .min_field_value = 1,
                .cpu_enable = cpu_enable_cnp,
        },
#endif
        {
                .desc = "Speculation barrier (SB)",
                .capability = ARM64_HAS_SB,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .field_pos = ID_AA64ISAR1_SB_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
        },
#ifdef CONFIG_ARM64_PTR_AUTH
        {
                .desc = "Address authentication (architected algorithm)",
                .capability = ARM64_HAS_ADDRESS_AUTH_ARCH,
                .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64ISAR1_APA_SHIFT,
                .min_field_value = ID_AA64ISAR1_APA_ARCHITECTED,
                .matches = has_cpuid_feature,
        },
        {
                .desc = "Address authentication (IMP DEF algorithm)",
                .capability = ARM64_HAS_ADDRESS_AUTH_IMP_DEF,
                .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64ISAR1_API_SHIFT,
                .min_field_value = ID_AA64ISAR1_API_IMP_DEF,
                .matches = has_cpuid_feature,
        },
        {
                .capability = ARM64_HAS_ADDRESS_AUTH,
                .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
                .matches = has_address_auth,
        },
        {
                .desc = "Generic authentication (architected algorithm)",
                .capability = ARM64_HAS_GENERIC_AUTH_ARCH,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64ISAR1_GPA_SHIFT,
                .min_field_value = ID_AA64ISAR1_GPA_ARCHITECTED,
                .matches = has_cpuid_feature,
        },
        {
                .desc = "Generic authentication (IMP DEF algorithm)",
                .capability = ARM64_HAS_GENERIC_AUTH_IMP_DEF,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .sys_reg = SYS_ID_AA64ISAR1_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64ISAR1_GPI_SHIFT,
                .min_field_value = ID_AA64ISAR1_GPI_IMP_DEF,
                .matches = has_cpuid_feature,
        },
        {
                .capability = ARM64_HAS_GENERIC_AUTH,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_generic_auth,
        },
#endif /* CONFIG_ARM64_PTR_AUTH */
#ifdef CONFIG_ARM64_PSEUDO_NMI
        {
                /*
                 * Depends on having GICv3
                 */
                .desc = "IRQ priority masking",
                .capability = ARM64_HAS_IRQ_PRIO_MASKING,
                .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
                .matches = can_use_gic_priorities,
                .sys_reg = SYS_ID_AA64PFR0_EL1,
                .field_pos = ID_AA64PFR0_GIC_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
        },
#endif
#ifdef CONFIG_ARM64_E0PD
        {
                .desc = "E0PD",
                .capability = ARM64_HAS_E0PD,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .sys_reg = SYS_ID_AA64MMFR2_EL1,
                .sign = FTR_UNSIGNED,
                .field_pos = ID_AA64MMFR2_E0PD_SHIFT,
                .matches = has_cpuid_feature,
                .min_field_value = 1,
                .cpu_enable = cpu_enable_e0pd,
        },
#endif
#ifdef CONFIG_ARCH_RANDOM
        {
                .desc = "Random Number Generator",
                .capability = ARM64_HAS_RNG,
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
                .matches = has_cpuid_feature,
                .sys_reg = SYS_ID_AA64ISAR0_EL1,
                .field_pos = ID_AA64ISAR0_RNDR_SHIFT,
                .sign = FTR_UNSIGNED,
                .min_field_value = 1,
        },
#endif
#ifdef CONFIG_ARM64_BTI
        {
                .desc = "Branch Target Identification",
                .capability = ARM64_BTI,
#ifdef CONFIG_ARM64_BTI_KERNEL
                .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
#else
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,
#endif
                .matches = has_cpuid_feature,
                .cpu_enable = bti_enable,
                .sys_reg = SYS_ID_AA64PFR1_EL1,
                .field_pos = ID_AA64PFR1_BT_SHIFT,
                .min_field_value = ID_AA64PFR1_BT_BTI,
                .sign = FTR_UNSIGNED,
        },
#endif
        {},
};

#define HWCAP_CPUID_MATCH(reg, field, s, min_value)                             \
                .matches = has_cpuid_feature,                                   \
                .sys_reg = reg,                                                 \
                .field_pos = field,                                             \
                .sign = s,                                                      \
                .min_field_value = min_value,

#define __HWCAP_CAP(name, cap_type, cap)                                        \
                .desc = name,                                                   \
                .type = ARM64_CPUCAP_SYSTEM_FEATURE,                            \
                .hwcap_type = cap_type,                                         \
                .hwcap = cap,                                                   \

#define HWCAP_CAP(reg, field, s, min_value, cap_type, cap)                      \
        {                                                                       \
                __HWCAP_CAP(#cap, cap_type, cap)                                \
                HWCAP_CPUID_MATCH(reg, field, s, min_value)                     \
        }

#define HWCAP_MULTI_CAP(list, cap_type, cap)                                    \
        {                                                                       \
                __HWCAP_CAP(#cap, cap_type, cap)                                \
                .matches = cpucap_multi_entry_cap_matches,                      \
                .match_list = list,                                             \
        }

#define HWCAP_CAP_MATCH(match, cap_type, cap)                                   \
        {                                                                       \
                __HWCAP_CAP(#cap, cap_type, cap)                                \
                .matches = match,                                               \
        }

#ifdef CONFIG_ARM64_PTR_AUTH
static const struct arm64_cpu_capabilities ptr_auth_hwcap_addr_matches[] = {
        {
                HWCAP_CPUID_MATCH(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_APA_SHIFT,
                                  FTR_UNSIGNED, ID_AA64ISAR1_APA_ARCHITECTED)
        },
        {
                HWCAP_CPUID_MATCH(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_API_SHIFT,
                                  FTR_UNSIGNED, ID_AA64ISAR1_API_IMP_DEF)
        },
        {},
};

static const struct arm64_cpu_capabilities ptr_auth_hwcap_gen_matches[] = {
        {
                HWCAP_CPUID_MATCH(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_GPA_SHIFT,
                                  FTR_UNSIGNED, ID_AA64ISAR1_GPA_ARCHITECTED)
        },
        {
                HWCAP_CPUID_MATCH(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_GPI_SHIFT,
                                  FTR_UNSIGNED, ID_AA64ISAR1_GPI_IMP_DEF)
        },
        {},
};
#endif

static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_PMULL),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_AES),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA1_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SHA1),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA2_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SHA2),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA2_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_SHA512),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_CRC32_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_CRC32),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_ATOMICS_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_ATOMICS),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_RDM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDRDM),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA3_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SHA3),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SM3_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SM3),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SM4_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SM4),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_DP_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDDP),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_FHM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDFHM),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FLAGM),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_FLAGM2),
        HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_RNDR_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_RNG),
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_FP),
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FPHP),
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, KERNEL_HWCAP_ASIMD),
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_ASIMDHP),
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_DIT_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DIT),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DCPOP),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_DCPODP),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_JSCVT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_JSCVT),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FCMA),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_LRCPC),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, KERNEL_HWCAP_ILRCPC),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FRINTTS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_FRINT),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_SB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_SB),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_BF16_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_BF16),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DGH_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_DGH),
        HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_I8MM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_I8MM),
        HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, KERNEL_HWCAP_USCAT),
#ifdef CONFIG_ARM64_SVE
        HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, KERNEL_HWCAP_SVE),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SVEVER_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SVEVER_SVE2, CAP_HWCAP, KERNEL_HWCAP_SVE2),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_AES_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_AES, CAP_HWCAP, KERNEL_HWCAP_SVEAES),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_AES_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_AES_PMULL, CAP_HWCAP, KERNEL_HWCAP_SVEPMULL),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_BITPERM_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_BITPERM, CAP_HWCAP, KERNEL_HWCAP_SVEBITPERM),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_BF16_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_BF16, CAP_HWCAP, KERNEL_HWCAP_SVEBF16),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SHA3_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SHA3, CAP_HWCAP, KERNEL_HWCAP_SVESHA3),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_SM4_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_SM4, CAP_HWCAP, KERNEL_HWCAP_SVESM4),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_I8MM_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_I8MM, CAP_HWCAP, KERNEL_HWCAP_SVEI8MM),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_F32MM_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_F32MM, CAP_HWCAP, KERNEL_HWCAP_SVEF32MM),
        HWCAP_CAP(SYS_ID_AA64ZFR0_EL1, ID_AA64ZFR0_F64MM_SHIFT, FTR_UNSIGNED, ID_AA64ZFR0_F64MM, CAP_HWCAP, KERNEL_HWCAP_SVEF64MM),
#endif
        HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_SSBS_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_SSBS_PSTATE_INSNS, CAP_HWCAP, KERNEL_HWCAP_SSBS),
#ifdef CONFIG_ARM64_BTI
        HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_BT_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_BT_BTI, CAP_HWCAP, KERNEL_HWCAP_BTI),
#endif
#ifdef CONFIG_ARM64_PTR_AUTH
        HWCAP_MULTI_CAP(ptr_auth_hwcap_addr_matches, CAP_HWCAP, KERNEL_HWCAP_PACA),
        HWCAP_MULTI_CAP(ptr_auth_hwcap_gen_matches, CAP_HWCAP, KERNEL_HWCAP_PACG),
#endif
        {},
};

#ifdef CONFIG_COMPAT
static bool compat_has_neon(const struct arm64_cpu_capabilities *cap, int scope)
{
        /*
         * Check that all of MVFR1_EL1.{SIMDSP, SIMDInt, SIMDLS} are available,
         * in line with that of arm32 as in vfp_init(). We make sure that the
         * check is future proof, by making sure value is non-zero.
         */
        u32 mvfr1;

        WARN_ON(scope == SCOPE_LOCAL_CPU && preemptible());
        if (scope == SCOPE_SYSTEM)
                mvfr1 = read_sanitised_ftr_reg(SYS_MVFR1_EL1);
        else
                mvfr1 = read_sysreg_s(SYS_MVFR1_EL1);

        return cpuid_feature_extract_unsigned_field(mvfr1, MVFR1_SIMDSP_SHIFT) &&
                cpuid_feature_extract_unsigned_field(mvfr1, MVFR1_SIMDINT_SHIFT) &&
                cpuid_feature_extract_unsigned_field(mvfr1, MVFR1_SIMDLS_SHIFT);
}
#endif

static const struct arm64_cpu_capabilities compat_elf_hwcaps[] = {
#ifdef CONFIG_COMPAT
        HWCAP_CAP_MATCH(compat_has_neon, CAP_COMPAT_HWCAP, COMPAT_HWCAP_NEON),
        HWCAP_CAP(SYS_MVFR1_EL1, MVFR1_SIMDFMAC_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP, COMPAT_HWCAP_VFPv4),
        /* Arm v8 mandates MVFR0.FPDP == {0, 2}. So, piggy back on this for the presence of VFP support */
        HWCAP_CAP(SYS_MVFR0_EL1, MVFR0_FPDP_SHIFT, FTR_UNSIGNED, 2, CAP_COMPAT_HWCAP, COMPAT_HWCAP_VFP),
        HWCAP_CAP(SYS_MVFR0_EL1, MVFR0_FPDP_SHIFT, FTR_UNSIGNED, 2, CAP_COMPAT_HWCAP, COMPAT_HWCAP_VFPv3),
        HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 2, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_PMULL),
        HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_AES),
        HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_SHA1_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SHA1),
        HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_SHA2_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SHA2),
        HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_CRC32_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_CRC32),
#endif
        {},
};

static void __init cap_set_elf_hwcap(const struct arm64_cpu_capabilities *cap)
{
        switch (cap->hwcap_type) {
        case CAP_HWCAP:
                cpu_set_feature(cap->hwcap);
                break;
#ifdef CONFIG_COMPAT
        case CAP_COMPAT_HWCAP:
                compat_elf_hwcap |= (u32)cap->hwcap;
                break;
        case CAP_COMPAT_HWCAP2:
                compat_elf_hwcap2 |= (u32)cap->hwcap;
                break;
#endif
        default:
                WARN_ON(1);
                break;
        }
}

/* Check if we have a particular HWCAP enabled */
static bool cpus_have_elf_hwcap(const struct arm64_cpu_capabilities *cap)
{
        bool rc;

        switch (cap->hwcap_type) {
        case CAP_HWCAP:
                rc = cpu_have_feature(cap->hwcap);
                break;
#ifdef CONFIG_COMPAT
        case CAP_COMPAT_HWCAP:
                rc = (compat_elf_hwcap & (u32)cap->hwcap) != 0;
                break;
        case CAP_COMPAT_HWCAP2:
                rc = (compat_elf_hwcap2 & (u32)cap->hwcap) != 0;
                break;
#endif
        default:
                WARN_ON(1);
                rc = false;
        }

        return rc;
}

static void __init setup_elf_hwcaps(const struct arm64_cpu_capabilities *hwcaps)
{
        /* We support emulation of accesses to CPU ID feature registers */
        cpu_set_named_feature(CPUID);
        for (; hwcaps->matches; hwcaps++)
                if (hwcaps->matches(hwcaps, cpucap_default_scope(hwcaps)))
                        cap_set_elf_hwcap(hwcaps);
}

static void update_cpu_capabilities(u16 scope_mask)
{
        int i;
        const struct arm64_cpu_capabilities *caps;

        scope_mask &= ARM64_CPUCAP_SCOPE_MASK;
        for (i = 0; i < ARM64_NCAPS; i++) {
                caps = cpu_hwcaps_ptrs[i];
                if (!caps || !(caps->type & scope_mask) ||
                    cpus_have_cap(caps->capability) ||
                    !caps->matches(caps, cpucap_default_scope(caps)))
                        continue;

                if (caps->desc)
                        pr_info("detected: %s\n", caps->desc);
                cpus_set_cap(caps->capability);

                if ((scope_mask & SCOPE_BOOT_CPU) && (caps->type & SCOPE_BOOT_CPU))
                        set_bit(caps->capability, boot_capabilities);
        }
}

/*
 * Enable all the available capabilities on this CPU. The capabilities
 * with BOOT_CPU scope are handled separately and hence skipped here.
 */
static int cpu_enable_non_boot_scope_capabilities(void *__unused)
{
        int i;
        u16 non_boot_scope = SCOPE_ALL & ~SCOPE_BOOT_CPU;

        for_each_available_cap(i) {
                const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[i];

                if (WARN_ON(!cap))
                        continue;

                if (!(cap->type & non_boot_scope))
                        continue;

                if (cap->cpu_enable)
                        cap->cpu_enable(cap);
        }
        return 0;
}

/*
 * Run through the enabled capabilities and enable() it on all active
 * CPUs
 */
static void __init enable_cpu_capabilities(u16 scope_mask)
{
        int i;
        const struct arm64_cpu_capabilities *caps;
        bool boot_scope;

        scope_mask &= ARM64_CPUCAP_SCOPE_MASK;
        boot_scope = !!(scope_mask & SCOPE_BOOT_CPU);

        for (i = 0; i < ARM64_NCAPS; i++) {
                unsigned int num;

                caps = cpu_hwcaps_ptrs[i];
                if (!caps || !(caps->type & scope_mask))
                        continue;
                num = caps->capability;
                if (!cpus_have_cap(num))
                        continue;

                /* Ensure cpus_have_const_cap(num) works */
                static_branch_enable(&cpu_hwcap_keys[num]);

                if (boot_scope && caps->cpu_enable)
                        /*
                         * Capabilities with SCOPE_BOOT_CPU scope are finalised
                         * before any secondary CPU boots. Thus, each secondary
                         * will enable the capability as appropriate via
                         * check_local_cpu_capabilities(). The only exception is
                         * the boot CPU, for which the capability must be
                         * enabled here. This approach avoids costly
                         * stop_machine() calls for this case.
                         */
                        caps->cpu_enable(caps);
        }

        /*
         * For all non-boot scope capabilities, use stop_machine()
         * as it schedules the work allowing us to modify PSTATE,
         * instead of on_each_cpu() which uses an IPI, giving us a
         * PSTATE that disappears when we return.
         */
        if (!boot_scope)
                stop_machine(cpu_enable_non_boot_scope_capabilities,
                             NULL, cpu_online_mask);
}

/*
 * Run through the list of capabilities to check for conflicts.
 * If the system has already detected a capability, take necessary
 * action on this CPU.
 */
static void verify_local_cpu_caps(u16 scope_mask)
{
        int i;
        bool cpu_has_cap, system_has_cap;
        const struct arm64_cpu_capabilities *caps;

        scope_mask &= ARM64_CPUCAP_SCOPE_MASK;

        for (i = 0; i < ARM64_NCAPS; i++) {
                caps = cpu_hwcaps_ptrs[i];
                if (!caps || !(caps->type & scope_mask))
                        continue;

                cpu_has_cap = caps->matches(caps, SCOPE_LOCAL_CPU);
                system_has_cap = cpus_have_cap(caps->capability);

                if (system_has_cap) {
                        /*
                         * Check if the new CPU misses an advertised feature,
                         * which is not safe to miss.
                         */
                        if (!cpu_has_cap && !cpucap_late_cpu_optional(caps))
                                break;
                        /*
                         * We have to issue cpu_enable() irrespective of
                         * whether the CPU has it or not, as it is enabeld
                         * system wide. It is upto the call back to take
                         * appropriate action on this CPU.
                         */
                        if (caps->cpu_enable)
                                caps->cpu_enable(caps);
                } else {
                        /*
                         * Check if the CPU has this capability if it isn't
                         * safe to have when the system doesn't.
                         */
                        if (cpu_has_cap && !cpucap_late_cpu_permitted(caps))
                                break;
                }
        }

        if (i < ARM64_NCAPS) {
                pr_crit("CPU%d: Detected conflict for capability %d (%s), System: %d, CPU: %d\n",
                        smp_processor_id(), caps->capability,
                        caps->desc, system_has_cap, cpu_has_cap);

                if (cpucap_panic_on_conflict(caps))
                        cpu_panic_kernel();
                else
                        cpu_die_early();
        }
}

/*
 * Check for CPU features that are used in early boot
 * based on the Boot CPU value.
 */
static void check_early_cpu_features(void)
{
        verify_cpu_asid_bits();

        verify_local_cpu_caps(SCOPE_BOOT_CPU);
}

static void
verify_local_elf_hwcaps(const struct arm64_cpu_capabilities *caps)
{

        for (; caps->matches; caps++)
                if (cpus_have_elf_hwcap(caps) && !caps->matches(caps, SCOPE_LOCAL_CPU)) {
                        pr_crit("CPU%d: missing HWCAP: %s\n",
                                        smp_processor_id(), caps->desc);
                        cpu_die_early();
                }
}

static void verify_sve_features(void)
{
        u64 safe_zcr = read_sanitised_ftr_reg(SYS_ZCR_EL1);
        u64 zcr = read_zcr_features();

        unsigned int safe_len = safe_zcr & ZCR_ELx_LEN_MASK;
        unsigned int len = zcr & ZCR_ELx_LEN_MASK;

        if (len < safe_len || sve_verify_vq_map()) {
                pr_crit("CPU%d: SVE: vector length support mismatch\n",
                        smp_processor_id());
                cpu_die_early();
        }

        /* Add checks on other ZCR bits here if necessary */
}

static void verify_hyp_capabilities(void)
{
        u64 safe_mmfr1, mmfr0, mmfr1;
        int parange, ipa_max;
        unsigned int safe_vmid_bits, vmid_bits;

        if (!IS_ENABLED(CONFIG_KVM) || !IS_ENABLED(CONFIG_KVM_ARM_HOST))
                return;

        safe_mmfr1 = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
        mmfr0 = read_cpuid(ID_AA64MMFR0_EL1);
        mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);

        /* Verify VMID bits */
        safe_vmid_bits = get_vmid_bits(safe_mmfr1);
        vmid_bits = get_vmid_bits(mmfr1);
        if (vmid_bits < safe_vmid_bits) {
                pr_crit("CPU%d: VMID width mismatch\n", smp_processor_id());
                cpu_die_early();
        }

        /* Verify IPA range */
        parange = cpuid_feature_extract_unsigned_field(mmfr0,
                                ID_AA64MMFR0_PARANGE_SHIFT);
        ipa_max = id_aa64mmfr0_parange_to_phys_shift(parange);
        if (ipa_max < get_kvm_ipa_limit()) {
                pr_crit("CPU%d: IPA range mismatch\n", smp_processor_id());
                cpu_die_early();
        }
}

/*
 * Run through the enabled system capabilities and enable() it on this CPU.
 * The capabilities were decided based on the available CPUs at the boot time.
 * Any new CPU should match the system wide status of the capability. If the
 * new CPU doesn't have a capability which the system now has enabled, we
 * cannot do anything to fix it up and could cause unexpected failures. So
 * we park the CPU.
 */
static void verify_local_cpu_capabilities(void)
{
        /*
         * The capabilities with SCOPE_BOOT_CPU are checked from
         * check_early_cpu_features(), as they need to be verified
         * on all secondary CPUs.
         */
        verify_local_cpu_caps(SCOPE_ALL & ~SCOPE_BOOT_CPU);

        verify_local_elf_hwcaps(arm64_elf_hwcaps);

        if (system_supports_32bit_el0())
                verify_local_elf_hwcaps(compat_elf_hwcaps);

        if (system_supports_sve())
                verify_sve_features();

        if (is_hyp_mode_available())
                verify_hyp_capabilities();
}

void check_local_cpu_capabilities(void)
{
        /*
         * All secondary CPUs should conform to the early CPU features
         * in use by the kernel based on boot CPU.
         */
        check_early_cpu_features();

        /*
         * If we haven't finalised the system capabilities, this CPU gets
         * a chance to update the errata work arounds and local features.
         * Otherwise, this CPU should verify that it has all the system
         * advertised capabilities.
         */
        if (!system_capabilities_finalized())
                update_cpu_capabilities(SCOPE_LOCAL_CPU);
        else
                verify_local_cpu_capabilities();
}

static void __init setup_boot_cpu_capabilities(void)
{
        /* Detect capabilities with either SCOPE_BOOT_CPU or SCOPE_LOCAL_CPU */
        update_cpu_capabilities(SCOPE_BOOT_CPU | SCOPE_LOCAL_CPU);
        /* Enable the SCOPE_BOOT_CPU capabilities alone right away */
        enable_cpu_capabilities(SCOPE_BOOT_CPU);
}

bool this_cpu_has_cap(unsigned int n)
{
        if (!WARN_ON(preemptible()) && n < ARM64_NCAPS) {
                const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n];

                if (cap)
                        return cap->matches(cap, SCOPE_LOCAL_CPU);
        }

        return false;
}

/*
 * This helper function is used in a narrow window when,
 * - The system wide safe registers are set with all the SMP CPUs and,
 * - The SYSTEM_FEATURE cpu_hwcaps may not have been set.
 * In all other cases cpus_have_{const_}cap() should be used.
 */
static bool __system_matches_cap(unsigned int n)
{
        if (n < ARM64_NCAPS) {
                const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n];

                if (cap)
                        return cap->matches(cap, SCOPE_SYSTEM);
        }
        return false;
}

void cpu_set_feature(unsigned int num)
{
        WARN_ON(num >= MAX_CPU_FEATURES);
        elf_hwcap |= BIT(num);
}
EXPORT_SYMBOL_GPL(cpu_set_feature);

bool cpu_have_feature(unsigned int num)
{
        WARN_ON(num >= MAX_CPU_FEATURES);
        return elf_hwcap & BIT(num);
}
EXPORT_SYMBOL_GPL(cpu_have_feature);

unsigned long cpu_get_elf_hwcap(void)
{
        /*
         * We currently only populate the first 32 bits of AT_HWCAP. Please
         * note that for userspace compatibility we guarantee that bits 62
         * and 63 will always be returned as 0.
         */
        return lower_32_bits(elf_hwcap);
}

unsigned long cpu_get_elf_hwcap2(void)
{
        return upper_32_bits(elf_hwcap);
}

static void __init setup_system_capabilities(void)
{
        /*
         * We have finalised the system-wide safe feature
         * registers, finalise the capabilities that depend
         * on it. Also enable all the available capabilities,
         * that are not enabled already.
         */
        update_cpu_capabilities(SCOPE_SYSTEM);
        enable_cpu_capabilities(SCOPE_ALL & ~SCOPE_BOOT_CPU);
}

void __init setup_cpu_features(void)
{
        u32 cwg;

        setup_system_capabilities();
        setup_elf_hwcaps(arm64_elf_hwcaps);

        if (system_supports_32bit_el0())
                setup_elf_hwcaps(compat_elf_hwcaps);

        if (system_uses_ttbr0_pan())
                pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");

        sve_setup();
        minsigstksz_setup();

        /* Advertise that we have computed the system capabilities */
        finalize_system_capabilities();

        /*
         * Check for sane CTR_EL0.CWG value.
         */
        cwg = cache_type_cwg();
        if (!cwg)
                pr_warn("No Cache Writeback Granule information, assuming %d\n",
                        ARCH_DMA_MINALIGN);
}

static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused)
{
        return (__system_matches_cap(ARM64_HAS_PAN) && !__system_matches_cap(ARM64_HAS_UAO));
}

static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
{
        cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
}

/*
 * We emulate only the following system register space.
 * Op0 = 0x3, CRn = 0x0, Op1 = 0x0, CRm = [0, 4 - 7]
 * See Table C5-6 System instruction encodings for System register accesses,
 * ARMv8 ARM(ARM DDI 0487A.f) for more details.
 */
static inline bool __attribute_const__ is_emulated(u32 id)
{
        return (sys_reg_Op0(id) == 0x3 &&
                sys_reg_CRn(id) == 0x0 &&
                sys_reg_Op1(id) == 0x0 &&
                (sys_reg_CRm(id) == 0 ||
                 ((sys_reg_CRm(id) >= 4) && (sys_reg_CRm(id) <= 7))));
}

/*
 * With CRm == 0, reg should be one of :
 * MIDR_EL1, MPIDR_EL1 or REVIDR_EL1.
 */
static inline int emulate_id_reg(u32 id, u64 *valp)
{
        switch (id) {
        case SYS_MIDR_EL1:
                *valp = read_cpuid_id();
                break;
        case SYS_MPIDR_EL1:
                *valp = SYS_MPIDR_SAFE_VAL;
                break;
        case SYS_REVIDR_EL1:
                /* IMPLEMENTATION DEFINED values are emulated with 0 */
                *valp = 0;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int emulate_sys_reg(u32 id, u64 *valp)
{
        struct arm64_ftr_reg *regp;

        if (!is_emulated(id))
                return -EINVAL;

        if (sys_reg_CRm(id) == 0)
                return emulate_id_reg(id, valp);

        regp = get_arm64_ftr_reg_nowarn(id);
        if (regp)
                *valp = arm64_ftr_reg_user_value(regp);
        else
                /*
                 * The untracked registers are either IMPLEMENTATION DEFINED
                 * (e.g, ID_AFR0_EL1) or reserved RAZ.
                 */
                *valp = 0;
        return 0;
}

int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt)
{
        int rc;
        u64 val;

        rc = emulate_sys_reg(sys_reg, &val);
        if (!rc) {
                pt_regs_write_reg(regs, rt, val);
                arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
        }
        return rc;
}

static int emulate_mrs(struct pt_regs *regs, u32 insn)
{
        u32 sys_reg, rt;

        /*
         * sys_reg values are defined as used in mrs/msr instruction.
         * shift the imm value to get the encoding.
         */
        sys_reg = (u32)aarch64_insn_decode_immediate(AARCH64_INSN_IMM_16, insn) << 5;
        rt = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RT, insn);
        return do_emulate_mrs(regs, sys_reg, rt);
}

static struct undef_hook mrs_hook = {
        .instr_mask = 0xfff00000,
        .instr_val  = 0xd5300000,
        .pstate_mask = PSR_AA32_MODE_MASK,
        .pstate_val = PSR_MODE_EL0t,
        .fn = emulate_mrs,
};

static int __init enable_mrs_emulation(void)
{
        register_undef_hook(&mrs_hook);
        return 0;
}

core_initcall(enable_mrs_emulation);

ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        if (__meltdown_safe)
                return sprintf(buf, "Not affected\n");

        if (arm64_kernel_unmapped_at_el0())
                return sprintf(buf, "Mitigation: PTI\n");

        return sprintf(buf, "Vulnerable\n");
}