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

   1/*
   2 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
   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
   9#include <linux/efi.h>
  10#include <asm/efi.h>
  11#include <asm/mach/map.h>
  12#include <asm/mmu_context.h>
  13
  14static int __init set_permissions(pte_t *ptep, pgtable_t token,
  15                                  unsigned long addr, void *data)
  16{
  17        efi_memory_desc_t *md = data;
  18        pte_t pte = *ptep;
  19
  20        if (md->attribute & EFI_MEMORY_RO)
  21                pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
  22        if (md->attribute & EFI_MEMORY_XP)
  23                pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
  24        set_pte_ext(ptep, pte, PTE_EXT_NG);
  25        return 0;
  26}
  27
  28int __init efi_set_mapping_permissions(struct mm_struct *mm,
  29                                       efi_memory_desc_t *md)
  30{
  31        unsigned long base, size;
  32
  33        base = md->virt_addr;
  34        size = md->num_pages << EFI_PAGE_SHIFT;
  35
  36        /*
  37         * We can only use apply_to_page_range() if we can guarantee that the
  38         * entire region was mapped using pages. This should be the case if the
  39         * region does not cover any naturally aligned SECTION_SIZE sized
  40         * blocks.
  41         */
  42        if (round_down(base + size, SECTION_SIZE) <
  43            round_up(base, SECTION_SIZE) + SECTION_SIZE)
  44                return apply_to_page_range(mm, base, size, set_permissions, md);
  45
  46        return 0;
  47}
  48
  49int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
  50{
  51        struct map_desc desc = {
  52                .virtual        = md->virt_addr,
  53                .pfn            = __phys_to_pfn(md->phys_addr),
  54                .length         = md->num_pages * EFI_PAGE_SIZE,
  55        };
  56
  57        /*
  58         * Order is important here: memory regions may have all of the
  59         * bits below set (and usually do), so we check them in order of
  60         * preference.
  61         */
  62        if (md->attribute & EFI_MEMORY_WB)
  63                desc.type = MT_MEMORY_RWX;
  64        else if (md->attribute & EFI_MEMORY_WT)
  65                desc.type = MT_MEMORY_RWX_NONCACHED;
  66        else if (md->attribute & EFI_MEMORY_WC)
  67                desc.type = MT_DEVICE_WC;
  68        else
  69                desc.type = MT_DEVICE;
  70
  71        create_mapping_late(mm, &desc, true);
  72
  73        /*
  74         * If stricter permissions were specified, apply them now.
  75         */
  76        if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
  77                return efi_set_mapping_permissions(mm, md);
  78        return 0;
  79}
  80