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 <linux/memblock.h>
   8 #include <asm/efi.h>
   9 #include <asm/mach/map.h>
  10 #include <asm/mmu_context.h>
  11
  12 static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
  13 {
  14         efi_memory_desc_t *md = data;
  15         pte_t pte = *ptep;
  16
  17         if (md->attribute & EFI_MEMORY_RO)
  18                 pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
  19         if (md->attribute & EFI_MEMORY_XP)
  20                 pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
  21         set_pte_ext(ptep, pte, PTE_EXT_NG);
  22         return 0;
  23 }
  24
  25 int __init efi_set_mapping_permissions(struct mm_struct *mm,
  26                                        efi_memory_desc_t *md,
  27                                        bool ignored)
  28 {
  29         unsigned long base, size;
  30
  31         base = md->virt_addr;
  32         size = md->num_pages << EFI_PAGE_SHIFT;
  33
  34         /*
  35          * We can only use apply_to_page_range() if we can guarantee that the
  36          * entire region was mapped using pages. This should be the case if the
  37          * region does not cover any naturally aligned SECTION_SIZE sized
  38          * blocks.
  39          */
  40         if (round_down(base + size, SECTION_SIZE) <
  41             round_up(base, SECTION_SIZE) + SECTION_SIZE)
  42                 return apply_to_page_range(mm, base, size, set_permissions, md);
  43
  44         return 0;
  45 }
  46
  47 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
  48 {
  49         struct map_desc desc = {
  50                 .virtual        = md->virt_addr,
  51                 .pfn            = __phys_to_pfn(md->phys_addr),
  52                 .length         = md->num_pages * EFI_PAGE_SIZE,
  53         };
  54
  55         /*
  56          * Order is important here: memory regions may have all of the
  57          * bits below set (and usually do), so we check them in order of
  58          * preference.
  59          */
  60         if (md->attribute & EFI_MEMORY_WB)
  61                 desc.type = MT_MEMORY_RWX;
  62         else if (md->attribute & EFI_MEMORY_WT)
  63                 desc.type = MT_MEMORY_RWX_NONCACHED;
  64         else if (md->attribute & EFI_MEMORY_WC)
  65                 desc.type = MT_DEVICE_WC;
  66         else
  67                 desc.type = MT_DEVICE;
  68
  69         create_mapping_late(mm, &desc, true);
  70
  71         /*
  72          * If stricter permissions were specified, apply them now.
  73          */
  74         if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
  75                 return efi_set_mapping_permissions(mm, md, false);
  76         return 0;
  77 }
  78
  79 static unsigned long __initdata cpu_state_table = EFI_INVALID_TABLE_ADDR;
  80
  81 const efi_config_table_type_t efi_arch_tables[] __initconst = {
  82         {LINUX_EFI_ARM_CPU_STATE_TABLE_GUID, &cpu_state_table},
  83         {}
  84 };
  85
  86 static void __init load_cpu_state_table(void)
  87 {
  88         if (cpu_state_table != EFI_INVALID_TABLE_ADDR) {
  89                 struct efi_arm_entry_state *state;
  90                 bool dump_state = true;
  91
  92                 state = early_memremap_ro(cpu_state_table,
  93                                           sizeof(struct efi_arm_entry_state));
  94                 if (state == NULL) {
  95                         pr_warn("Unable to map CPU entry state table.\n");
  96                         return;
  97                 }
  98
  99                 if ((state->sctlr_before_ebs & 1) == 0)
 100                         pr_warn(FW_BUG "EFI stub was entered with MMU and Dcache disabled, please fix your firmware!\n");
 101                 else if ((state->sctlr_after_ebs & 1) == 0)
 102                         pr_warn(FW_BUG "ExitBootServices() returned with MMU and Dcache disabled, please fix your firmware!\n");
 103                 else
 104                         dump_state = false;
 105
 106                 if (dump_state || efi_enabled(EFI_DBG)) {
 107                         pr_info("CPSR at EFI stub entry        : 0x%08x\n",
 108                                 state->cpsr_before_ebs);
 109                         pr_info("SCTLR at EFI stub entry       : 0x%08x\n",
 110                                 state->sctlr_before_ebs);
 111                         pr_info("CPSR after ExitBootServices() : 0x%08x\n",
 112                                 state->cpsr_after_ebs);
 113                         pr_info("SCTLR after ExitBootServices(): 0x%08x\n",
 114                                 state->sctlr_after_ebs);
 115                 }
 116                 early_memunmap(state, sizeof(struct efi_arm_entry_state));
 117         }
 118 }
 119
 120 void __init arm_efi_init(void)
 121 {
 122         efi_init();
 123
 124         if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI) {
 125                 /* dummycon on ARM needs non-zero values for columns/lines */
 126                 screen_info.orig_video_cols = 80;
 127                 screen_info.orig_video_lines = 25;
 128         }
 129
 130         /* ARM does not permit early mappings to persist across paging_init() */
 131         efi_memmap_unmap();
 132
 133         load_cpu_state_table();
 134 }