LXR linux/arch/arm/kernel/efi.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
   4 */
   5
   6#include <linux/efi.h>
   7#include <asm/efi.h>
   8#include <asm/mach/map.h>
   9#include <asm/mmu_context.h>
  10
  11static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
  12{
  13        efi_memory_desc_t *md = data;
  14        pte_t pte = *ptep;
  15
  16        if (md->attribute & EFI_MEMORY_RO)
  17                pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
  18        if (md->attribute & EFI_MEMORY_XP)
  19                pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
  20        set_pte_ext(ptep, pte, PTE_EXT_NG);
  21        return 0;
  22}
  23
  24int __init efi_set_mapping_permissions(struct mm_struct *mm,
  25                                       efi_memory_desc_t *md)
  26{
  27        unsigned long base, size;
  28
  29        base = md->virt_addr;
  30        size = md->num_pages << EFI_PAGE_SHIFT;
  31
  32        /*
  33         * We can only use apply_to_page_range() if we can guarantee that the
  34         * entire region was mapped using pages. This should be the case if the
  35         * region does not cover any naturally aligned SECTION_SIZE sized
  36         * blocks.
  37         */
  38        if (round_down(base + size, SECTION_SIZE) <
  39            round_up(base, SECTION_SIZE) + SECTION_SIZE)
  40                return apply_to_page_range(mm, base, size, set_permissions, md);
  41
  42        return 0;
  43}
  44
  45int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
  46{
  47        struct map_desc desc = {
  48                .virtual        = md->virt_addr,
  49                .pfn            = __phys_to_pfn(md->phys_addr),
  50                .length         = md->num_pages * EFI_PAGE_SIZE,
  51        };
  52
  53        /*
  54         * Order is important here: memory regions may have all of the
  55         * bits below set (and usually do), so we check them in order of
  56         * preference.
  57         */
  58        if (md->attribute & EFI_MEMORY_WB)
  59                desc.type = MT_MEMORY_RWX;
  60        else if (md->attribute & EFI_MEMORY_WT)
  61                desc.type = MT_MEMORY_RWX_NONCACHED;
  62        else if (md->attribute & EFI_MEMORY_WC)
  63                desc.type = MT_DEVICE_WC;
  64        else
  65                desc.type = MT_DEVICE;
  66
  67        create_mapping_late(mm, &desc, true);
  68
  69        /*
  70         * If stricter permissions were specified, apply them now.
  71         */
  72        if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
  73                return efi_set_mapping_permissions(mm, md);
  74        return 0;
  75}
  76