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 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
  43 #include <asm/ptdump.h>
  44
  45 static struct ptdump_info efi_ptdump_info = {
  46         .mm             = &efi_mm,
  47         .markers        = (struct addr_marker[]){
  48                 { 0,            "UEFI runtime start" },
  49                 { TASK_SIZE_64, "UEFI runtime end" }
  50         },
  51         .base_addr      = 0,
  52 };
  53
  54 static int __init ptdump_init(void)
  55 {
  56         return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
  57 }
  58 device_initcall(ptdump_init);
  59
  60 #endif
  61
  62 static bool __init efi_virtmap_init(void)
  63 {
  64         efi_memory_desc_t *md;
  65         bool systab_found;
  66
  67         efi_mm.pgd = pgd_alloc(&efi_mm);
  68         init_new_context(NULL, &efi_mm);
  69
  70         systab_found = false;
  71         for_each_efi_memory_desc(md) {
  72                 phys_addr_t phys = md->phys_addr;
  73                 int ret;
  74
  75                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  76                         continue;
  77                 if (md->virt_addr == 0)
  78                         return false;
  79
  80                 ret = efi_create_mapping(&efi_mm, md);
  81                 if  (!ret) {
  82                         pr_info("  EFI remap %pa => %p\n",
  83                                 &phys, (void *)(unsigned long)md->virt_addr);
  84                 } else {
  85                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  86                                 &phys, ret);
  87                         return false;
  88                 }
  89                 /*
  90                  * If this entry covers the address of the UEFI system table,
  91                  * calculate and record its virtual address.
  92                  */
  93                 if (efi_system_table >= phys &&
  94                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
  95                         efi.systab = (void *)(unsigned long)(efi_system_table -
  96                                                              phys + md->virt_addr);
  97                         systab_found = true;
  98                 }
  99         }
 100         if (!systab_found) {
 101                 pr_err("No virtual mapping found for the UEFI System Table\n");
 102                 return false;
 103         }
 104
 105         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
 106                 return false;
 107
 108         return true;
 109 }
 110
 111 /*
 112  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 113  * non-early mapping of the UEFI system table and virtual mappings for all
 114  * EFI_MEMORY_RUNTIME regions.
 115  */
 116 static int __init arm_enable_runtime_services(void)
 117 {
 118         u64 mapsize;
 119
 120         if (!efi_enabled(EFI_BOOT)) {
 121                 pr_info("EFI services will not be available.\n");
 122                 return 0;
 123         }
 124
 125         if (efi_runtime_disabled()) {
 126                 pr_info("EFI runtime services will be disabled.\n");
 127                 return 0;
 128         }
 129
 130         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 131                 pr_info("EFI runtime services access via paravirt.\n");
 132                 return 0;
 133         }
 134
 135         pr_info("Remapping and enabling EFI services.\n");
 136
 137         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 138
 139         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 140                 pr_err("Failed to remap EFI memory map\n");
 141                 return -ENOMEM;
 142         }
 143
 144         if (!efi_virtmap_init()) {
 145                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 146                 return -ENOMEM;
 147         }
 148
 149         /* Set up runtime services function pointers */
 150         efi_native_runtime_setup();
 151         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 152
 153         return 0;
 154 }
 155 early_initcall(arm_enable_runtime_services);
 156
 157 void efi_virtmap_load(void)
 158 {
 159         preempt_disable();
 160         efi_set_pgd(&efi_mm);
 161 }
 162
 163 void efi_virtmap_unload(void)
 164 {
 165         efi_set_pgd(current->active_mm);
 166         preempt_enable();
 167 }