x86/ldt: Make the LDT mapping RO

[mirror_ubuntu-bionic-kernel.git] / arch / x86 / platform / efi / efi_64.c

// SPDX-License-Identifier: GPL-2.0
/*
 * x86_64 specific EFI support functions
 * Based on Extensible Firmware Interface Specification version 1.0
 *
 * Copyright (C) 2005-2008 Intel Co.
 *      Fenghua Yu <fenghua.yu@intel.com>
 *      Bibo Mao <bibo.mao@intel.com>
 *      Chandramouli Narayanan <mouli@linux.intel.com>
 *      Huang Ying <ying.huang@intel.com>
 *
 * Code to convert EFI to E820 map has been implemented in elilo bootloader
 * based on a EFI patch by Edgar Hucek. Based on the E820 map, the page table
 * is setup appropriately for EFI runtime code.
 * - mouli 06/14/2007.
 *
 */

#define pr_fmt(fmt) "efi: " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/bootmem.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/efi.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>

#include <asm/setup.h>
#include <asm/page.h>
#include <asm/e820/api.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm/efi.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
#include <asm/realmode.h>
#include <asm/time.h>
#include <asm/pgalloc.h>

/*
 * We allocate runtime services regions top-down, starting from -4G, i.e.
 * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
 */
static u64 efi_va = EFI_VA_START;

struct efi_scratch efi_scratch;

static void __init early_code_mapping_set_exec(int executable)
{
        efi_memory_desc_t *md;

        if (!(__supported_pte_mask & _PAGE_NX))
                return;

        /* Make EFI service code area executable */
        for_each_efi_memory_desc(md) {
                if (md->type == EFI_RUNTIME_SERVICES_CODE ||
                    md->type == EFI_BOOT_SERVICES_CODE)
                        efi_set_executable(md, executable);
        }
}

pgd_t * __init efi_call_phys_prolog(void)
{
        unsigned long vaddr, addr_pgd, addr_p4d, addr_pud;
        pgd_t *save_pgd, *pgd_k, *pgd_efi;
        p4d_t *p4d, *p4d_k, *p4d_efi;
        pud_t *pud;

        int pgd;
        int n_pgds, i, j;

        if (!efi_enabled(EFI_OLD_MEMMAP)) {
                save_pgd = (pgd_t *)__read_cr3();
                write_cr3((unsigned long)efi_scratch.efi_pgt);
                goto out;
        }

        early_code_mapping_set_exec(1);

        n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
        save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL);

        /*
         * Build 1:1 identity mapping for efi=old_map usage. Note that
         * PAGE_OFFSET is PGDIR_SIZE aligned when KASLR is disabled, while
         * it is PUD_SIZE ALIGNED with KASLR enabled. So for a given physical
         * address X, the pud_index(X) != pud_index(__va(X)), we can only copy
         * PUD entry of __va(X) to fill in pud entry of X to build 1:1 mapping.
         * This means here we can only reuse the PMD tables of the direct mapping.
         */
        for (pgd = 0; pgd < n_pgds; pgd++) {
                addr_pgd = (unsigned long)(pgd * PGDIR_SIZE);
                vaddr = (unsigned long)__va(pgd * PGDIR_SIZE);
                pgd_efi = pgd_offset_k(addr_pgd);
                save_pgd[pgd] = *pgd_efi;

                p4d = p4d_alloc(&init_mm, pgd_efi, addr_pgd);
                if (!p4d) {
                        pr_err("Failed to allocate p4d table!\n");
                        goto out;
                }

                for (i = 0; i < PTRS_PER_P4D; i++) {
                        addr_p4d = addr_pgd + i * P4D_SIZE;
                        p4d_efi = p4d + p4d_index(addr_p4d);

                        pud = pud_alloc(&init_mm, p4d_efi, addr_p4d);
                        if (!pud) {
                                pr_err("Failed to allocate pud table!\n");
                                goto out;
                        }

                        for (j = 0; j < PTRS_PER_PUD; j++) {
                                addr_pud = addr_p4d + j * PUD_SIZE;

                                if (addr_pud > (max_pfn << PAGE_SHIFT))
                                        break;

                                vaddr = (unsigned long)__va(addr_pud);

                                pgd_k = pgd_offset_k(vaddr);
                                p4d_k = p4d_offset(pgd_k, vaddr);
                                pud[j] = *pud_offset(p4d_k, vaddr);
                        }
                }
        }
out:
        __flush_tlb_all();

        return save_pgd;
}

void __init efi_call_phys_epilog(pgd_t *save_pgd)
{
        /*
         * After the lock is released, the original page table is restored.
         */
        int pgd_idx, i;
        int nr_pgds;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;

        if (!efi_enabled(EFI_OLD_MEMMAP)) {
                write_cr3((unsigned long)save_pgd);
                __flush_tlb_all();
                return;
        }

        nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);

        for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++) {
                pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);
                set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);

                if (!(pgd_val(*pgd) & _PAGE_PRESENT))
                        continue;

                for (i = 0; i < PTRS_PER_P4D; i++) {
                        p4d = p4d_offset(pgd,
                                         pgd_idx * PGDIR_SIZE + i * P4D_SIZE);

                        if (!(p4d_val(*p4d) & _PAGE_PRESENT))
                                continue;

                        pud = (pud_t *)p4d_page_vaddr(*p4d);
                        pud_free(&init_mm, pud);
                }

                p4d = (p4d_t *)pgd_page_vaddr(*pgd);
                p4d_free(&init_mm, p4d);
        }

        kfree(save_pgd);

        __flush_tlb_all();
        early_code_mapping_set_exec(0);
}

static pgd_t *efi_pgd;

/*
 * We need our own copy of the higher levels of the page tables
 * because we want to avoid inserting EFI region mappings (EFI_VA_END
 * to EFI_VA_START) into the standard kernel page tables. Everything
 * else can be shared, see efi_sync_low_kernel_mappings().
 *
 * We don't want the pgd on the pgd_list and cannot use pgd_alloc() for the
 * allocation.
 */
int __init efi_alloc_page_tables(void)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        gfp_t gfp_mask;

        if (efi_enabled(EFI_OLD_MEMMAP))
                return 0;

        gfp_mask = GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO;
        efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, PGD_ALLOCATION_ORDER);
        if (!efi_pgd)
                return -ENOMEM;

        pgd = efi_pgd + pgd_index(EFI_VA_END);
        p4d = p4d_alloc(&init_mm, pgd, EFI_VA_END);
        if (!p4d) {
                free_page((unsigned long)efi_pgd);
                return -ENOMEM;
        }

        pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
        if (!pud) {
                if (CONFIG_PGTABLE_LEVELS > 4)
                        free_page((unsigned long) pgd_page_vaddr(*pgd));
                free_page((unsigned long)efi_pgd);
                return -ENOMEM;
        }

        return 0;
}

/*
 * Add low kernel mappings for passing arguments to EFI functions.
 */
void efi_sync_low_kernel_mappings(void)
{
        unsigned num_entries;
        pgd_t *pgd_k, *pgd_efi;
        p4d_t *p4d_k, *p4d_efi;
        pud_t *pud_k, *pud_efi;

        if (efi_enabled(EFI_OLD_MEMMAP))
                return;

        /*
         * We can share all PGD entries apart from the one entry that
         * covers the EFI runtime mapping space.
         *
         * Make sure the EFI runtime region mappings are guaranteed to
         * only span a single PGD entry and that the entry also maps
         * other important kernel regions.
         */
        BUILD_BUG_ON(pgd_index(EFI_VA_END) != pgd_index(MODULES_END));
        BUILD_BUG_ON((EFI_VA_START & PGDIR_MASK) !=
                        (EFI_VA_END & PGDIR_MASK));

        pgd_efi = efi_pgd + pgd_index(PAGE_OFFSET);
        pgd_k = pgd_offset_k(PAGE_OFFSET);

        num_entries = pgd_index(EFI_VA_END) - pgd_index(PAGE_OFFSET);
        memcpy(pgd_efi, pgd_k, sizeof(pgd_t) * num_entries);

        /*
         * As with PGDs, we share all P4D entries apart from the one entry
         * that covers the EFI runtime mapping space.
         */
        BUILD_BUG_ON(p4d_index(EFI_VA_END) != p4d_index(MODULES_END));
        BUILD_BUG_ON((EFI_VA_START & P4D_MASK) != (EFI_VA_END & P4D_MASK));

        pgd_efi = efi_pgd + pgd_index(EFI_VA_END);
        pgd_k = pgd_offset_k(EFI_VA_END);
        p4d_efi = p4d_offset(pgd_efi, 0);
        p4d_k = p4d_offset(pgd_k, 0);

        num_entries = p4d_index(EFI_VA_END);
        memcpy(p4d_efi, p4d_k, sizeof(p4d_t) * num_entries);

        /*
         * We share all the PUD entries apart from those that map the
         * EFI regions. Copy around them.
         */
        BUILD_BUG_ON((EFI_VA_START & ~PUD_MASK) != 0);
        BUILD_BUG_ON((EFI_VA_END & ~PUD_MASK) != 0);

        p4d_efi = p4d_offset(pgd_efi, EFI_VA_END);
        p4d_k = p4d_offset(pgd_k, EFI_VA_END);
        pud_efi = pud_offset(p4d_efi, 0);
        pud_k = pud_offset(p4d_k, 0);

        num_entries = pud_index(EFI_VA_END);
        memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries);

        pud_efi = pud_offset(p4d_efi, EFI_VA_START);
        pud_k = pud_offset(p4d_k, EFI_VA_START);

        num_entries = PTRS_PER_PUD - pud_index(EFI_VA_START);
        memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries);
}

/*
 * Wrapper for slow_virt_to_phys() that handles NULL addresses.
 */
static inline phys_addr_t
virt_to_phys_or_null_size(void *va, unsigned long size)
{
        bool bad_size;

        if (!va)
                return 0;

        if (virt_addr_valid(va))
                return virt_to_phys(va);

        /*
         * A fully aligned variable on the stack is guaranteed not to
         * cross a page bounary. Try to catch strings on the stack by
         * checking that 'size' is a power of two.
         */
        bad_size = size > PAGE_SIZE || !is_power_of_2(size);

        WARN_ON(!IS_ALIGNED((unsigned long)va, size) || bad_size);

        return slow_virt_to_phys(va);
}

#define virt_to_phys_or_null(addr)                              \
        virt_to_phys_or_null_size((addr), sizeof(*(addr)))

int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
        unsigned long pfn, text, pf;
        struct page *page;
        unsigned npages;
        pgd_t *pgd;

        if (efi_enabled(EFI_OLD_MEMMAP))
                return 0;

        /*
         * Since the PGD is encrypted, set the encryption mask so that when
         * this value is loaded into cr3 the PGD will be decrypted during
         * the pagetable walk.
         */
        efi_scratch.efi_pgt = (pgd_t *)__sme_pa(efi_pgd);
        pgd = efi_pgd;

        /*
         * It can happen that the physical address of new_memmap lands in memory
         * which is not mapped in the EFI page table. Therefore we need to go
         * and ident-map those pages containing the map before calling
         * phys_efi_set_virtual_address_map().
         */
        pfn = pa_memmap >> PAGE_SHIFT;
        pf = _PAGE_NX | _PAGE_RW | _PAGE_ENC;
        if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, pf)) {
                pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);
                return 1;
        }

        efi_scratch.use_pgd = true;

        /*
         * Certain firmware versions are way too sentimential and still believe
         * they are exclusive and unquestionable owners of the first physical page,
         * even though they explicitly mark it as EFI_CONVENTIONAL_MEMORY
         * (but then write-access it later during SetVirtualAddressMap()).
         *
         * Create a 1:1 mapping for this page, to avoid triple faults during early
         * boot with such firmware. We are free to hand this page to the BIOS,
         * as trim_bios_range() will reserve the first page and isolate it away
         * from memory allocators anyway.
         */
        if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
                pr_err("Failed to create 1:1 mapping for the first page!\n");
                return 1;
        }

        /*
         * When making calls to the firmware everything needs to be 1:1
         * mapped and addressable with 32-bit pointers. Map the kernel
         * text and allocate a new stack because we can't rely on the
         * stack pointer being < 4GB.
         */
        if (!IS_ENABLED(CONFIG_EFI_MIXED) || efi_is_native())
                return 0;

        page = alloc_page(GFP_KERNEL|__GFP_DMA32);
        if (!page)
                panic("Unable to allocate EFI runtime stack < 4GB\n");

        efi_scratch.phys_stack = virt_to_phys(page_address(page));
        efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */

        npages = (_etext - _text) >> PAGE_SHIFT;
        text = __pa(_text);
        pfn = text >> PAGE_SHIFT;

        pf = _PAGE_RW | _PAGE_ENC;
        if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, pf)) {
                pr_err("Failed to map kernel text 1:1\n");
                return 1;
        }

        return 0;
}

static void __init __map_region(efi_memory_desc_t *md, u64 va)
{
        unsigned long flags = _PAGE_RW;
        unsigned long pfn;
        pgd_t *pgd = efi_pgd;

        if (!(md->attribute & EFI_MEMORY_WB))
                flags |= _PAGE_PCD;

        pfn = md->phys_addr >> PAGE_SHIFT;
        if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
                pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
                           md->phys_addr, va);
}

void __init efi_map_region(efi_memory_desc_t *md)
{
        unsigned long size = md->num_pages << PAGE_SHIFT;
        u64 pa = md->phys_addr;

        if (efi_enabled(EFI_OLD_MEMMAP))
                return old_map_region(md);

        /*
         * Make sure the 1:1 mappings are present as a catch-all for b0rked
         * firmware which doesn't update all internal pointers after switching
         * to virtual mode and would otherwise crap on us.
         */
        __map_region(md, md->phys_addr);

        /*
         * Enforce the 1:1 mapping as the default virtual address when
         * booting in EFI mixed mode, because even though we may be
         * running a 64-bit kernel, the firmware may only be 32-bit.
         */
        if (!efi_is_native () && IS_ENABLED(CONFIG_EFI_MIXED)) {
                md->virt_addr = md->phys_addr;
                return;
        }

        efi_va -= size;

        /* Is PA 2M-aligned? */
        if (!(pa & (PMD_SIZE - 1))) {
                efi_va &= PMD_MASK;
        } else {
                u64 pa_offset = pa & (PMD_SIZE - 1);
                u64 prev_va = efi_va;

                /* get us the same offset within this 2M page */
                efi_va = (efi_va & PMD_MASK) + pa_offset;

                if (efi_va > prev_va)
                        efi_va -= PMD_SIZE;
        }

        if (efi_va < EFI_VA_END) {
                pr_warn(FW_WARN "VA address range overflow!\n");
                return;
        }

        /* Do the VA map */
        __map_region(md, efi_va);
        md->virt_addr = efi_va;
}

/*
 * kexec kernel will use efi_map_region_fixed to map efi runtime memory ranges.
 * md->virt_addr is the original virtual address which had been mapped in kexec
 * 1st kernel.
 */
void __init efi_map_region_fixed(efi_memory_desc_t *md)
{
        __map_region(md, md->phys_addr);
        __map_region(md, md->virt_addr);
}

void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size,
                                 u32 type, u64 attribute)
{
        unsigned long last_map_pfn;

        if (type == EFI_MEMORY_MAPPED_IO)
                return ioremap(phys_addr, size);

        last_map_pfn = init_memory_mapping(phys_addr, phys_addr + size);
        if ((last_map_pfn << PAGE_SHIFT) < phys_addr + size) {
                unsigned long top = last_map_pfn << PAGE_SHIFT;
                efi_ioremap(top, size - (top - phys_addr), type, attribute);
        }

        if (!(attribute & EFI_MEMORY_WB))
                efi_memory_uc((u64)(unsigned long)__va(phys_addr), size);

        return (void __iomem *)__va(phys_addr);
}

void __init parse_efi_setup(u64 phys_addr, u32 data_len)
{
        efi_setup = phys_addr + sizeof(struct setup_data);
}

static int __init efi_update_mappings(efi_memory_desc_t *md, unsigned long pf)
{
        unsigned long pfn;
        pgd_t *pgd = efi_pgd;
        int err1, err2;

        /* Update the 1:1 mapping */
        pfn = md->phys_addr >> PAGE_SHIFT;
        err1 = kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, md->num_pages, pf);
        if (err1) {
                pr_err("Error while updating 1:1 mapping PA 0x%llx -> VA 0x%llx!\n",
                           md->phys_addr, md->virt_addr);
        }

        err2 = kernel_map_pages_in_pgd(pgd, pfn, md->virt_addr, md->num_pages, pf);
        if (err2) {
                pr_err("Error while updating VA mapping PA 0x%llx -> VA 0x%llx!\n",
                           md->phys_addr, md->virt_addr);
        }

        return err1 || err2;
}

static int __init efi_update_mem_attr(struct mm_struct *mm, efi_memory_desc_t *md)
{
        unsigned long pf = 0;

        if (md->attribute & EFI_MEMORY_XP)
                pf |= _PAGE_NX;

        if (!(md->attribute & EFI_MEMORY_RO))
                pf |= _PAGE_RW;

        return efi_update_mappings(md, pf);
}

void __init efi_runtime_update_mappings(void)
{
        efi_memory_desc_t *md;

        if (efi_enabled(EFI_OLD_MEMMAP)) {
                if (__supported_pte_mask & _PAGE_NX)
                        runtime_code_page_mkexec();
                return;
        }

        /*
         * Use the EFI Memory Attribute Table for mapping permissions if it
         * exists, since it is intended to supersede EFI_PROPERTIES_TABLE.
         */
        if (efi_enabled(EFI_MEM_ATTR)) {
                efi_memattr_apply_permissions(NULL, efi_update_mem_attr);
                return;
        }

        /*
         * EFI_MEMORY_ATTRIBUTES_TABLE is intended to replace
         * EFI_PROPERTIES_TABLE. So, use EFI_PROPERTIES_TABLE to update
         * permissions only if EFI_MEMORY_ATTRIBUTES_TABLE is not
         * published by the firmware. Even if we find a buggy implementation of
         * EFI_MEMORY_ATTRIBUTES_TABLE, don't fall back to
         * EFI_PROPERTIES_TABLE, because of the same reason.
         */

        if (!efi_enabled(EFI_NX_PE_DATA))
                return;

        for_each_efi_memory_desc(md) {
                unsigned long pf = 0;

                if (!(md->attribute & EFI_MEMORY_RUNTIME))
                        continue;

                if (!(md->attribute & EFI_MEMORY_WB))
                        pf |= _PAGE_PCD;

                if ((md->attribute & EFI_MEMORY_XP) ||
                        (md->type == EFI_RUNTIME_SERVICES_DATA))
                        pf |= _PAGE_NX;

                if (!(md->attribute & EFI_MEMORY_RO) &&
                        (md->type != EFI_RUNTIME_SERVICES_CODE))
                        pf |= _PAGE_RW;

                efi_update_mappings(md, pf);
        }
}

void __init efi_dump_pagetable(void)
{
#ifdef CONFIG_EFI_PGT_DUMP
        if (efi_enabled(EFI_OLD_MEMMAP))
                ptdump_walk_pgd_level(NULL, swapper_pg_dir);
        else
                ptdump_walk_pgd_level(NULL, efi_pgd);
#endif
}

#ifdef CONFIG_EFI_MIXED
extern efi_status_t efi64_thunk(u32, ...);

#define runtime_service32(func)                                          \
({                                                                       \
        u32 table = (u32)(unsigned long)efi.systab;                      \
        u32 *rt, *___f;                                                  \
                                                                         \
        rt = (u32 *)(table + offsetof(efi_system_table_32_t, runtime));  \
        ___f = (u32 *)(*rt + offsetof(efi_runtime_services_32_t, func)); \
        *___f;                                                           \
})

/*
 * Switch to the EFI page tables early so that we can access the 1:1
 * runtime services mappings which are not mapped in any other page
 * tables. This function must be called before runtime_service32().
 *
 * Also, disable interrupts because the IDT points to 64-bit handlers,
 * which aren't going to function correctly when we switch to 32-bit.
 */
#define efi_thunk(f, ...)                                               \
({                                                                      \
        efi_status_t __s;                                               \
        unsigned long __flags;                                          \
        u32 __func;                                                     \
                                                                        \
        local_irq_save(__flags);                                        \
        arch_efi_call_virt_setup();                                     \
                                                                        \
        __func = runtime_service32(f);                                  \
        __s = efi64_thunk(__func, __VA_ARGS__);                         \
                                                                        \
        arch_efi_call_virt_teardown();                                  \
        local_irq_restore(__flags);                                     \
                                                                        \
        __s;                                                            \
})

efi_status_t efi_thunk_set_virtual_address_map(
        void *phys_set_virtual_address_map,
        unsigned long memory_map_size,
        unsigned long descriptor_size,
        u32 descriptor_version,
        efi_memory_desc_t *virtual_map)
{
        efi_status_t status;
        unsigned long flags;
        u32 func;

        efi_sync_low_kernel_mappings();
        local_irq_save(flags);

        efi_scratch.prev_cr3 = __read_cr3();
        write_cr3((unsigned long)efi_scratch.efi_pgt);
        __flush_tlb_all();

        func = (u32)(unsigned long)phys_set_virtual_address_map;
        status = efi64_thunk(func, memory_map_size, descriptor_size,
                             descriptor_version, virtual_map);

        write_cr3(efi_scratch.prev_cr3);
        __flush_tlb_all();
        local_irq_restore(flags);

        return status;
}

static efi_status_t efi_thunk_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
        efi_status_t status;
        u32 phys_tm, phys_tc;

        spin_lock(&rtc_lock);

        phys_tm = virt_to_phys_or_null(tm);
        phys_tc = virt_to_phys_or_null(tc);

        status = efi_thunk(get_time, phys_tm, phys_tc);

        spin_unlock(&rtc_lock);

        return status;
}

static efi_status_t efi_thunk_set_time(efi_time_t *tm)
{
        efi_status_t status;
        u32 phys_tm;

        spin_lock(&rtc_lock);

        phys_tm = virt_to_phys_or_null(tm);

        status = efi_thunk(set_time, phys_tm);

        spin_unlock(&rtc_lock);

        return status;
}

static efi_status_t
efi_thunk_get_wakeup_time(efi_bool_t *enabled, efi_bool_t *pending,
                          efi_time_t *tm)
{
        efi_status_t status;
        u32 phys_enabled, phys_pending, phys_tm;

        spin_lock(&rtc_lock);

        phys_enabled = virt_to_phys_or_null(enabled);
        phys_pending = virt_to_phys_or_null(pending);
        phys_tm = virt_to_phys_or_null(tm);

        status = efi_thunk(get_wakeup_time, phys_enabled,
                             phys_pending, phys_tm);

        spin_unlock(&rtc_lock);

        return status;
}

static efi_status_t
efi_thunk_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
{
        efi_status_t status;
        u32 phys_tm;

        spin_lock(&rtc_lock);

        phys_tm = virt_to_phys_or_null(tm);

        status = efi_thunk(set_wakeup_time, enabled, phys_tm);

        spin_unlock(&rtc_lock);

        return status;
}

static unsigned long efi_name_size(efi_char16_t *name)
{
        return ucs2_strsize(name, EFI_VAR_NAME_LEN) + 1;
}

static efi_status_t
efi_thunk_get_variable(efi_char16_t *name, efi_guid_t *vendor,
                       u32 *attr, unsigned long *data_size, void *data)
{
        efi_status_t status;
        u32 phys_name, phys_vendor, phys_attr;
        u32 phys_data_size, phys_data;

        phys_data_size = virt_to_phys_or_null(data_size);
        phys_vendor = virt_to_phys_or_null(vendor);
        phys_name = virt_to_phys_or_null_size(name, efi_name_size(name));
        phys_attr = virt_to_phys_or_null(attr);
        phys_data = virt_to_phys_or_null_size(data, *data_size);

        status = efi_thunk(get_variable, phys_name, phys_vendor,
                           phys_attr, phys_data_size, phys_data);

        return status;
}

static efi_status_t
efi_thunk_set_variable(efi_char16_t *name, efi_guid_t *vendor,
                       u32 attr, unsigned long data_size, void *data)
{
        u32 phys_name, phys_vendor, phys_data;
        efi_status_t status;

        phys_name = virt_to_phys_or_null_size(name, efi_name_size(name));
        phys_vendor = virt_to_phys_or_null(vendor);
        phys_data = virt_to_phys_or_null_size(data, data_size);

        /* If data_size is > sizeof(u32) we've got problems */
        status = efi_thunk(set_variable, phys_name, phys_vendor,
                           attr, data_size, phys_data);

        return status;
}

static efi_status_t
efi_thunk_get_next_variable(unsigned long *name_size,
                            efi_char16_t *name,
                            efi_guid_t *vendor)
{
        efi_status_t status;
        u32 phys_name_size, phys_name, phys_vendor;

        phys_name_size = virt_to_phys_or_null(name_size);
        phys_vendor = virt_to_phys_or_null(vendor);
        phys_name = virt_to_phys_or_null_size(name, *name_size);

        status = efi_thunk(get_next_variable, phys_name_size,
                           phys_name, phys_vendor);

        return status;
}

static efi_status_t
efi_thunk_get_next_high_mono_count(u32 *count)
{
        efi_status_t status;
        u32 phys_count;

        phys_count = virt_to_phys_or_null(count);
        status = efi_thunk(get_next_high_mono_count, phys_count);

        return status;
}

static void
efi_thunk_reset_system(int reset_type, efi_status_t status,
                       unsigned long data_size, efi_char16_t *data)
{
        u32 phys_data;

        phys_data = virt_to_phys_or_null_size(data, data_size);

        efi_thunk(reset_system, reset_type, status, data_size, phys_data);
}

static efi_status_t
efi_thunk_update_capsule(efi_capsule_header_t **capsules,
                         unsigned long count, unsigned long sg_list)
{
        /*
         * To properly support this function we would need to repackage
         * 'capsules' because the firmware doesn't understand 64-bit
         * pointers.
         */
        return EFI_UNSUPPORTED;
}

static efi_status_t
efi_thunk_query_variable_info(u32 attr, u64 *storage_space,
                              u64 *remaining_space,
                              u64 *max_variable_size)
{
        efi_status_t status;
        u32 phys_storage, phys_remaining, phys_max;

        if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
                return EFI_UNSUPPORTED;

        phys_storage = virt_to_phys_or_null(storage_space);
        phys_remaining = virt_to_phys_or_null(remaining_space);
        phys_max = virt_to_phys_or_null(max_variable_size);

        status = efi_thunk(query_variable_info, attr, phys_storage,
                           phys_remaining, phys_max);

        return status;
}

static efi_status_t
efi_thunk_query_capsule_caps(efi_capsule_header_t **capsules,
                             unsigned long count, u64 *max_size,
                             int *reset_type)
{
        /*
         * To properly support this function we would need to repackage
         * 'capsules' because the firmware doesn't understand 64-bit
         * pointers.
         */
        return EFI_UNSUPPORTED;
}

void efi_thunk_runtime_setup(void)
{
        efi.get_time = efi_thunk_get_time;
        efi.set_time = efi_thunk_set_time;
        efi.get_wakeup_time = efi_thunk_get_wakeup_time;
        efi.set_wakeup_time = efi_thunk_set_wakeup_time;
        efi.get_variable = efi_thunk_get_variable;
        efi.get_next_variable = efi_thunk_get_next_variable;
        efi.set_variable = efi_thunk_set_variable;
        efi.get_next_high_mono_count = efi_thunk_get_next_high_mono_count;
        efi.reset_system = efi_thunk_reset_system;
        efi.query_variable_info = efi_thunk_query_variable_info;
        efi.update_capsule = efi_thunk_update_capsule;
        efi.query_capsule_caps = efi_thunk_query_capsule_caps;
}
#endif /* CONFIG_EFI_MIXED */