arch/arm64/include/asm/mmu.h

   1 /*
   2  * Copyright (C) 2012 ARM Ltd.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15  */
  16 #ifndef __ASM_MMU_H
  17 #define __ASM_MMU_H
  18
  19 #include <asm/cputype.h>
  20
  21 #define MMCF_AARCH32    0x1     /* mm context flag for AArch32 executables */
  22 #define USER_ASID_BIT   48
  23 #define USER_ASID_FLAG  (UL(1) << USER_ASID_BIT)
  24 #define TTBR_ASID_MASK  (UL(0xffff) << 48)
  25
  26 #define BP_HARDEN_EL2_SLOTS 4
  27
  28 #ifndef __ASSEMBLY__
  29
  30 typedef struct {
  31         atomic64_t      id;
  32         void            *vdso;
  33         unsigned long   flags;
  34 } mm_context_t;
  35
  36 /*
  37  * This macro is only used by the TLBI code, which cannot race with an
  38  * ASID change and therefore doesn't need to reload the counter using
  39  * atomic64_read.
  40  */
  41 #define ASID(mm)        ((mm)->context.id.counter & 0xffff)
  42
  43 static inline bool arm64_kernel_unmapped_at_el0(void)
  44 {
  45         return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) &&
  46                cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
  47 }
  48
  49 static inline bool arm64_kernel_use_ng_mappings(void)
  50 {
  51         bool tx1_bug;
  52
  53         /* What's a kpti? Use global mappings if we don't know. */
  54         if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0))
  55                 return false;
  56
  57         /*
  58          * Note: this function is called before the CPU capabilities have
  59          * been configured, so our early mappings will be global. If we
  60          * later determine that kpti is required, then
  61          * kpti_install_ng_mappings() will make them non-global.
  62          */
  63         if (arm64_kernel_unmapped_at_el0())
  64                 return true;
  65
  66         if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
  67                 return false;
  68
  69         /*
  70          * KASLR is enabled so we're going to be enabling kpti on non-broken
  71          * CPUs regardless of their susceptibility to Meltdown. Rather
  72          * than force everybody to go through the G -> nG dance later on,
  73          * just put down non-global mappings from the beginning.
  74          */
  75         if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
  76                 tx1_bug = false;
  77 #ifndef MODULE
  78         } else if (!static_branch_likely(&arm64_const_caps_ready)) {
  79                 extern const struct midr_range cavium_erratum_27456_cpus[];
  80
  81                 tx1_bug = is_midr_in_range_list(read_cpuid_id(),
  82                                                 cavium_erratum_27456_cpus);
  83 #endif
  84         } else {
  85                 tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456);
  86         }
  87
  88         return !tx1_bug && kaslr_offset() > 0;
  89 }
  90
  91 typedef void (*bp_hardening_cb_t)(void);
  92
  93 struct bp_hardening_data {
  94         int                     hyp_vectors_slot;
  95         bp_hardening_cb_t       fn;
  96 };
  97
  98 #if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) || \
  99      defined(CONFIG_HARDEN_EL2_VECTORS))
 100 extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[];
 101 extern atomic_t arm64_el2_vector_last_slot;
 102 #endif  /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */
 103
 104 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
 105 DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
 106
 107 static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
 108 {
 109         return this_cpu_ptr(&bp_hardening_data);
 110 }
 111
 112 static inline void arm64_apply_bp_hardening(void)
 113 {
 114         struct bp_hardening_data *d;
 115
 116         if (!cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR))
 117                 return;
 118
 119         d = arm64_get_bp_hardening_data();
 120         if (d->fn)
 121                 d->fn();
 122 }
 123 #else
 124 static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
 125 {
 126         return NULL;
 127 }
 128
 129 static inline void arm64_apply_bp_hardening(void)       { }
 130 #endif  /* CONFIG_HARDEN_BRANCH_PREDICTOR */
 131
 132 extern void paging_init(void);
 133 extern void bootmem_init(void);
 134 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
 135 extern void init_mem_pgprot(void);
 136 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 137                                unsigned long virt, phys_addr_t size,
 138                                pgprot_t prot, bool page_mappings_only);
 139 extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
 140 extern void mark_linear_text_alias_ro(void);
 141
 142 #define INIT_MM_CONTEXT(name)   \
 143         .pgd = init_pg_dir,
 144
 145 #endif  /* !__ASSEMBLY__ */
 146 #endif