drivers/firmware/efi/arm-runtime.c

   1 /*
   2  * Extensible Firmware Interface
   3  *
   4  * Based on Extensible Firmware Interface Specification version 2.4
   5  *
   6  * Copyright (C) 2013, 2014 Linaro Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13
  14 #include <linux/efi.h>
  15 #include <linux/io.h>
  16 #include <linux/memblock.h>
  17 #include <linux/mm_types.h>
  18 #include <linux/preempt.h>
  19 #include <linux/rbtree.h>
  20 #include <linux/rwsem.h>
  21 #include <linux/sched.h>
  22 #include <linux/slab.h>
  23 #include <linux/spinlock.h>
  24
  25 #include <asm/cacheflush.h>
  26 #include <asm/efi.h>
  27 #include <asm/mmu.h>
  28 #include <asm/pgalloc.h>
  29 #include <asm/pgtable.h>
  30
  31 extern u64 efi_system_table;
  32
  33 static struct mm_struct efi_mm = {
  34         .mm_rb                  = RB_ROOT,
  35         .mm_users               = ATOMIC_INIT(2),
  36         .mm_count               = ATOMIC_INIT(1),
  37         .mmap_sem               = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
  38         .page_table_lock        = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
  39         .mmlist                 = LIST_HEAD_INIT(efi_mm.mmlist),
  40 };
  41
  42 static bool __init efi_virtmap_init(void)
  43 {
  44         efi_memory_desc_t *md;
  45         bool systab_found;
  46
  47         efi_mm.pgd = pgd_alloc(&efi_mm);
  48         init_new_context(NULL, &efi_mm);
  49
  50         systab_found = false;
  51         for_each_efi_memory_desc(md) {
  52                 phys_addr_t phys = md->phys_addr;
  53                 int ret;
  54
  55                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  56                         continue;
  57                 if (md->virt_addr == 0)
  58                         return false;
  59
  60                 ret = efi_create_mapping(&efi_mm, md);
  61                 if  (!ret) {
  62                         pr_info("  EFI remap %pa => %p\n",
  63                                 &phys, (void *)(unsigned long)md->virt_addr);
  64                 } else {
  65                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  66                                 &phys, ret);
  67                         return false;
  68                 }
  69                 /*
  70                  * If this entry covers the address of the UEFI system table,
  71                  * calculate and record its virtual address.
  72                  */
  73                 if (efi_system_table >= phys &&
  74                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
  75                         efi.systab = (void *)(unsigned long)(efi_system_table -
  76                                                              phys + md->virt_addr);
  77                         systab_found = true;
  78                 }
  79         }
  80         if (!systab_found) {
  81                 pr_err("No virtual mapping found for the UEFI System Table\n");
  82                 return false;
  83         }
  84
  85         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
  86                 return false;
  87
  88         return true;
  89 }
  90
  91 /*
  92  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
  93  * non-early mapping of the UEFI system table and virtual mappings for all
  94  * EFI_MEMORY_RUNTIME regions.
  95  */
  96 static int __init arm_enable_runtime_services(void)
  97 {
  98         u64 mapsize;
  99
 100         if (!efi_enabled(EFI_BOOT)) {
 101                 pr_info("EFI services will not be available.\n");
 102                 return 0;
 103         }
 104
 105         if (efi_runtime_disabled()) {
 106                 pr_info("EFI runtime services will be disabled.\n");
 107                 return 0;
 108         }
 109
 110         pr_info("Remapping and enabling EFI services.\n");
 111
 112         mapsize = efi.memmap.map_end - efi.memmap.map;
 113
 114         efi.memmap.map = memremap(efi.memmap.phys_map, mapsize, MEMREMAP_WB);
 115         if (!efi.memmap.map) {
 116                 pr_err("Failed to remap EFI memory map\n");
 117                 return -ENOMEM;
 118         }
 119         efi.memmap.map_end = efi.memmap.map + mapsize;
 120
 121         if (!efi_virtmap_init()) {
 122                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 123                 return -ENOMEM;
 124         }
 125
 126         /* Set up runtime services function pointers */
 127         efi_native_runtime_setup();
 128         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 129
 130         return 0;
 131 }
 132 early_initcall(arm_enable_runtime_services);
 133
 134 void efi_virtmap_load(void)
 135 {
 136         preempt_disable();
 137         efi_set_pgd(&efi_mm);
 138 }
 139
 140 void efi_virtmap_unload(void)
 141 {
 142         efi_set_pgd(current->active_mm);
 143         preempt_enable();
 144 }