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 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
  35 #include <asm/ptdump.h>
  36
  37 static struct ptdump_info efi_ptdump_info = {
  38         .mm             = &efi_mm,
  39         .markers        = (struct addr_marker[]){
  40                 { 0,                            "UEFI runtime start" },
  41                 { DEFAULT_MAP_WINDOW_64,        "UEFI runtime end" },
  42                 { -1,                           NULL }
  43         },
  44         .base_addr      = 0,
  45 };
  46
  47 static int __init ptdump_init(void)
  48 {
  49         if (!efi_enabled(EFI_RUNTIME_SERVICES))
  50                 return 0;
  51
  52         return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
  53 }
  54 device_initcall(ptdump_init);
  55
  56 #endif
  57
  58 static bool __init efi_virtmap_init(void)
  59 {
  60         efi_memory_desc_t *md;
  61         bool systab_found;
  62
  63         efi_mm.pgd = pgd_alloc(&efi_mm);
  64         mm_init_cpumask(&efi_mm);
  65         init_new_context(NULL, &efi_mm);
  66
  67         systab_found = false;
  68         for_each_efi_memory_desc(md) {
  69                 phys_addr_t phys = md->phys_addr;
  70                 int ret;
  71
  72                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  73                         continue;
  74                 if (md->virt_addr == 0)
  75                         return false;
  76
  77                 ret = efi_create_mapping(&efi_mm, md);
  78                 if (ret) {
  79                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  80                                 &phys, ret);
  81                         return false;
  82                 }
  83                 /*
  84                  * If this entry covers the address of the UEFI system table,
  85                  * calculate and record its virtual address.
  86                  */
  87                 if (efi_system_table >= phys &&
  88                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
  89                         efi.systab = (void *)(unsigned long)(efi_system_table -
  90                                                              phys + md->virt_addr);
  91                         systab_found = true;
  92                 }
  93         }
  94         if (!systab_found) {
  95                 pr_err("No virtual mapping found for the UEFI System Table\n");
  96                 return false;
  97         }
  98
  99         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
 100                 return false;
 101
 102         return true;
 103 }
 104
 105 /*
 106  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 107  * non-early mapping of the UEFI system table and virtual mappings for all
 108  * EFI_MEMORY_RUNTIME regions.
 109  */
 110 static int __init arm_enable_runtime_services(void)
 111 {
 112         u64 mapsize;
 113
 114         if (!efi_enabled(EFI_BOOT)) {
 115                 pr_info("EFI services will not be available.\n");
 116                 return 0;
 117         }
 118
 119         efi_memmap_unmap();
 120
 121         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 122
 123         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 124                 pr_err("Failed to remap EFI memory map\n");
 125                 return 0;
 126         }
 127
 128         if (efi_runtime_disabled()) {
 129                 pr_info("EFI runtime services will be disabled.\n");
 130                 return 0;
 131         }
 132
 133         if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 134                 pr_info("EFI runtime services access via paravirt.\n");
 135                 return 0;
 136         }
 137
 138         pr_info("Remapping and enabling EFI services.\n");
 139
 140         if (!efi_virtmap_init()) {
 141                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 142                 return -ENOMEM;
 143         }
 144
 145         /* Set up runtime services function pointers */
 146         efi_native_runtime_setup();
 147         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 148
 149         return 0;
 150 }
 151 early_initcall(arm_enable_runtime_services);
 152
 153 void efi_virtmap_load(void)
 154 {
 155         preempt_disable();
 156         efi_set_pgd(&efi_mm);
 157 }
 158
 159 void efi_virtmap_unload(void)
 160 {
 161         efi_set_pgd(current->active_mm);
 162         preempt_enable();
 163 }
 164
 165
 166 static int __init arm_dmi_init(void)
 167 {
 168         /*
 169          * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
 170          * be called early because dmi_id_init(), which is an arch_initcall
 171          * itself, depends on dmi_scan_machine() having been called already.
 172          */
 173         dmi_scan_machine();
 174         if (dmi_available)
 175                 dmi_set_dump_stack_arch_desc();
 176         return 0;
 177 }
 178 core_initcall(arm_dmi_init);