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         return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
  58 }
  59 device_initcall(ptdump_init);
  60
  61 #endif
  62
  63 static bool __init efi_virtmap_init(void)
  64 {
  65         efi_memory_desc_t *md;
  66         bool systab_found;
  67
  68         efi_mm.pgd = pgd_alloc(&efi_mm);
  69         mm_init_cpumask(&efi_mm);
  70         init_new_context(NULL, &efi_mm);
  71
  72         systab_found = false;
  73         for_each_efi_memory_desc(md) {
  74                 phys_addr_t phys = md->phys_addr;
  75                 int ret;
  76
  77                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  78                         continue;
  79                 if (md->virt_addr == 0)
  80                         return false;
  81
  82                 ret = efi_create_mapping(&efi_mm, md);
  83                 if  (!ret) {
  84                         pr_info("  EFI remap %pa => %p\n",
  85                                 &phys, (void *)(unsigned long)md->virt_addr);
  86                 } else {
  87                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  88                                 &phys, ret);
  89                         return false;
  90                 }
  91                 /*
  92                  * If this entry covers the address of the UEFI system table,
  93                  * calculate and record its virtual address.
  94                  */
  95                 if (efi_system_table >= phys &&
  96                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
  97                         efi.systab = (void *)(unsigned long)(efi_system_table -
  98                                                              phys + md->virt_addr);
  99                         systab_found = true;
 100                 }
 101         }
 102         if (!systab_found) {
 103                 pr_err("No virtual mapping found for the UEFI System Table\n");
 104                 return false;
 105         }
 106
 107         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
 108                 return false;
 109
 110         return true;
 111 }
 112
 113 /*
 114  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 115  * non-early mapping of the UEFI system table and virtual mappings for all
 116  * EFI_MEMORY_RUNTIME regions.
 117  */
 118 static int __init arm_enable_runtime_services(void)
 119 {
 120         u64 mapsize;
 121
 122         if (!efi_enabled(EFI_BOOT)) {
 123                 pr_info("EFI services will not be available.\n");
 124                 return 0;
 125         }
 126
 127         if (efi_runtime_disabled()) {
 128                 pr_info("EFI runtime services will be disabled.\n");
 129                 return 0;
 130         }
 131
 132         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 133                 pr_info("EFI runtime services access via paravirt.\n");
 134                 return 0;
 135         }
 136
 137         pr_info("Remapping and enabling EFI services.\n");
 138
 139         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 140
 141         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 142                 pr_err("Failed to remap EFI memory map\n");
 143                 return -ENOMEM;
 144         }
 145
 146         if (!efi_virtmap_init()) {
 147                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 148                 return -ENOMEM;
 149         }
 150
 151         /* Set up runtime services function pointers */
 152         efi_native_runtime_setup();
 153         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 154
 155         return 0;
 156 }
 157 early_initcall(arm_enable_runtime_services);
 158
 159 void efi_virtmap_load(void)
 160 {
 161         preempt_disable();
 162         efi_set_pgd(&efi_mm);
 163 }
 164
 165 void efi_virtmap_unload(void)
 166 {
 167         efi_set_pgd(current->active_mm);
 168         preempt_enable();
 169 }
 170
 171
 172 static int __init arm_dmi_init(void)
 173 {
 174         /*
 175          * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
 176          * be called early because dmi_id_init(), which is an arch_initcall
 177          * itself, depends on dmi_scan_machine() having been called already.
 178          */
 179         dmi_scan_machine();
 180         if (dmi_available)
 181                 dmi_set_dump_stack_arch_desc();
 182         return 0;
 183 }
 184 core_initcall(arm_dmi_init);