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/dmi.h>
  15 #include <linux/efi.h>
  16 #include <linux/io.h>
  17 #include <linux/memblock.h>
  18 #include <linux/mm_types.h>
  19 #include <linux/preempt.h>
  20 #include <linux/rbtree.h>
  21 #include <linux/rwsem.h>
  22 #include <linux/sched.h>
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25
  26 #include <asm/cacheflush.h>
  27 #include <asm/efi.h>
  28 #include <asm/mmu.h>
  29 #include <asm/pgalloc.h>
  30 #include <asm/pgtable.h>
  31
  32 extern u64 efi_system_table;
  33
  34 static struct mm_struct efi_mm = {
  35         .mm_rb                  = RB_ROOT,
  36         .mm_users               = ATOMIC_INIT(2),
  37         .mm_count               = ATOMIC_INIT(1),
  38         .mmap_sem               = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
  39         .page_table_lock        = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
  40         .mmlist                 = LIST_HEAD_INIT(efi_mm.mmlist),
  41 };
  42
  43 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
  44 #include <asm/ptdump.h>
  45
  46 static struct ptdump_info efi_ptdump_info = {
  47         .mm             = &efi_mm,
  48         .markers        = (struct addr_marker[]){
  49                 { 0,            "UEFI runtime start" },
  50                 { TASK_SIZE_64, "UEFI runtime end" }
  51         },
  52         .base_addr      = 0,
  53 };
  54
  55 static int __init ptdump_init(void)
  56 {
  57         if (!efi_enabled(EFI_RUNTIME_SERVICES))
  58                 return 0;
  59
  60         return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
  61 }
  62 device_initcall(ptdump_init);
  63
  64 #endif
  65
  66 static bool __init efi_virtmap_init(void)
  67 {
  68         efi_memory_desc_t *md;
  69         bool systab_found;
  70
  71         efi_mm.pgd = pgd_alloc(&efi_mm);
  72         mm_init_cpumask(&efi_mm);
  73         init_new_context(NULL, &efi_mm);
  74
  75         systab_found = false;
  76         for_each_efi_memory_desc(md) {
  77                 phys_addr_t phys = md->phys_addr;
  78                 int ret;
  79
  80                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  81                         continue;
  82                 if (md->virt_addr == 0)
  83                         return false;
  84
  85                 ret = efi_create_mapping(&efi_mm, md);
  86                 if  (!ret) {
  87                         pr_info("  EFI remap %pa => %p\n",
  88                                 &phys, (void *)(unsigned long)md->virt_addr);
  89                 } else {
  90                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  91                                 &phys, ret);
  92                         return false;
  93                 }
  94                 /*
  95                  * If this entry covers the address of the UEFI system table,
  96                  * calculate and record its virtual address.
  97                  */
  98                 if (efi_system_table >= phys &&
  99                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
 100                         efi.systab = (void *)(unsigned long)(efi_system_table -
 101                                                              phys + md->virt_addr);
 102                         systab_found = true;
 103                 }
 104         }
 105         if (!systab_found) {
 106                 pr_err("No virtual mapping found for the UEFI System Table\n");
 107                 return false;
 108         }
 109
 110         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
 111                 return false;
 112
 113         return true;
 114 }
 115
 116 /*
 117  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 118  * non-early mapping of the UEFI system table and virtual mappings for all
 119  * EFI_MEMORY_RUNTIME regions.
 120  */
 121 static int __init arm_enable_runtime_services(void)
 122 {
 123         u64 mapsize;
 124
 125         if (!efi_enabled(EFI_BOOT)) {
 126                 pr_info("EFI services will not be available.\n");
 127                 return 0;
 128         }
 129
 130         efi_memmap_unmap();
 131
 132         if (efi_runtime_disabled()) {
 133                 pr_info("EFI runtime services will be disabled.\n");
 134                 return 0;
 135         }
 136
 137         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 138                 pr_info("EFI runtime services access via paravirt.\n");
 139                 return 0;
 140         }
 141
 142         pr_info("Remapping and enabling EFI services.\n");
 143
 144         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 145
 146         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 147                 pr_err("Failed to remap EFI memory map\n");
 148                 return -ENOMEM;
 149         }
 150
 151         if (!efi_virtmap_init()) {
 152                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 153                 return -ENOMEM;
 154         }
 155
 156         /* Set up runtime services function pointers */
 157         efi_native_runtime_setup();
 158         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 159
 160         return 0;
 161 }
 162 early_initcall(arm_enable_runtime_services);
 163
 164 void efi_virtmap_load(void)
 165 {
 166         preempt_disable();
 167         efi_set_pgd(&efi_mm);
 168 }
 169
 170 void efi_virtmap_unload(void)
 171 {
 172         efi_set_pgd(current->active_mm);
 173         preempt_enable();
 174 }
 175
 176
 177 static int __init arm_dmi_init(void)
 178 {
 179         /*
 180          * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
 181          * be called early because dmi_id_init(), which is an arch_initcall
 182          * itself, depends on dmi_scan_machine() having been called already.
 183          */
 184         dmi_scan_machine();
 185         if (dmi_available)
 186                 dmi_set_dump_stack_arch_desc();
 187         return 0;
 188 }
 189 core_initcall(arm_dmi_init);