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                 { TASK_SIZE_64, "UEFI runtime end" }
  42         },
  43         .base_addr      = 0,
  44 };
  45
  46 static int __init ptdump_init(void)
  47 {
  48         if (!efi_enabled(EFI_RUNTIME_SERVICES))
  49                 return 0;
  50
  51         return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
  52 }
  53 device_initcall(ptdump_init);
  54
  55 #endif
  56
  57 static bool __init efi_virtmap_init(void)
  58 {
  59         efi_memory_desc_t *md;
  60         bool systab_found;
  61
  62         efi_mm.pgd = pgd_alloc(&efi_mm);
  63         mm_init_cpumask(&efi_mm);
  64         init_new_context(NULL, &efi_mm);
  65
  66         systab_found = false;
  67         for_each_efi_memory_desc(md) {
  68                 phys_addr_t phys = md->phys_addr;
  69                 int ret;
  70
  71                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  72                         continue;
  73                 if (md->virt_addr == 0)
  74                         return false;
  75
  76                 ret = efi_create_mapping(&efi_mm, md);
  77                 if (ret) {
  78                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  79                                 &phys, ret);
  80                         return false;
  81                 }
  82                 /*
  83                  * If this entry covers the address of the UEFI system table,
  84                  * calculate and record its virtual address.
  85                  */
  86                 if (efi_system_table >= phys &&
  87                     efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
  88                         efi.systab = (void *)(unsigned long)(efi_system_table -
  89                                                              phys + md->virt_addr);
  90                         systab_found = true;
  91                 }
  92         }
  93         if (!systab_found) {
  94                 pr_err("No virtual mapping found for the UEFI System Table\n");
  95                 return false;
  96         }
  97
  98         if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
  99                 return false;
 100
 101         return true;
 102 }
 103
 104 /*
 105  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 106  * non-early mapping of the UEFI system table and virtual mappings for all
 107  * EFI_MEMORY_RUNTIME regions.
 108  */
 109 static int __init arm_enable_runtime_services(void)
 110 {
 111         u64 mapsize;
 112
 113         if (!efi_enabled(EFI_BOOT) || !efi_enabled(EFI_MEMMAP)) {
 114                 pr_info("EFI services will not be available.\n");
 115                 return 0;
 116         }
 117
 118         efi_memmap_unmap();
 119
 120         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 121
 122         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 123                 pr_err("Failed to remap EFI memory map\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         if (!efi_virtmap_init()) {
 140                 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 141                 return -ENOMEM;
 142         }
 143
 144         /* Set up runtime services function pointers */
 145         efi_native_runtime_setup();
 146         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 147
 148         return 0;
 149 }
 150 early_initcall(arm_enable_runtime_services);
 151
 152 void efi_virtmap_load(void)
 153 {
 154         preempt_disable();
 155         efi_set_pgd(&efi_mm);
 156 }
 157
 158 void efi_virtmap_unload(void)
 159 {
 160         efi_set_pgd(current->active_mm);
 161         preempt_enable();
 162 }
 163
 164
 165 static int __init arm_dmi_init(void)
 166 {
 167         /*
 168          * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
 169          * be called early because dmi_id_init(), which is an arch_initcall
 170          * itself, depends on dmi_scan_machine() having been called already.
 171          */
 172         dmi_scan_machine();
 173         if (dmi_available)
 174                 dmi_set_dump_stack_arch_desc();
 175         return 0;
 176 }
 177 core_initcall(arm_dmi_init);