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 static bool __init efi_virtmap_init(void)
  43 {
  44         efi_memory_desc_t *md;
  45
  46         efi_mm.pgd = pgd_alloc(&efi_mm);
  47         init_new_context(NULL, &efi_mm);
  48
  49         for_each_efi_memory_desc(&memmap, md) {
  50                 phys_addr_t phys = md->phys_addr;
  51                 int ret;
  52
  53                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  54                         continue;
  55                 if (md->virt_addr == 0)
  56                         return false;
  57
  58                 ret = efi_create_mapping(&efi_mm, md);
  59                 if  (!ret) {
  60                         pr_info("  EFI remap %pa => %p\n",
  61                                 &phys, (void *)(unsigned long)md->virt_addr);
  62                 } else {
  63                         pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  64                                 &phys, ret);
  65                         return false;
  66                 }
  67         }
  68         return true;
  69 }
  70
  71 /*
  72  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
  73  * non-early mapping of the UEFI system table and virtual mappings for all
  74  * EFI_MEMORY_RUNTIME regions.
  75  */
  76 static int __init arm_enable_runtime_services(void)
  77 {
  78         u64 mapsize;
  79
  80         if (!efi_enabled(EFI_BOOT)) {
  81                 pr_info("EFI services will not be available.\n");
  82                 return 0;
  83         }
  84
  85         if (efi_runtime_disabled()) {
  86                 pr_info("EFI runtime services will be disabled.\n");
  87                 return 0;
  88         }
  89
  90         pr_info("Remapping and enabling EFI services.\n");
  91
  92         mapsize = memmap.map_end - memmap.map;
  93         memmap.map = (__force void *)ioremap_cache(memmap.phys_map,
  94                                                    mapsize);
  95         if (!memmap.map) {
  96                 pr_err("Failed to remap EFI memory map\n");
  97                 return -ENOMEM;
  98         }
  99         memmap.map_end = memmap.map + mapsize;
 100         efi.memmap = &memmap;
 101
 102         efi.systab = (__force void *)ioremap_cache(efi_system_table,
 103                                                    sizeof(efi_system_table_t));
 104         if (!efi.systab) {
 105                 pr_err("Failed to remap EFI System Table\n");
 106                 return -ENOMEM;
 107         }
 108         set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 109
 110         if (!efi_virtmap_init()) {
 111                 pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 112                 return -ENOMEM;
 113         }
 114
 115         /* Set up runtime services function pointers */
 116         efi_native_runtime_setup();
 117         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 118
 119         efi.runtime_version = efi.systab->hdr.revision;
 120
 121         return 0;
 122 }
 123 early_initcall(arm_enable_runtime_services);
 124
 125 void efi_virtmap_load(void)
 126 {
 127         preempt_disable();
 128         efi_set_pgd(&efi_mm);
 129 }
 130
 131 void efi_virtmap_unload(void)
 132 {
 133         efi_set_pgd(current->active_mm);
 134         preempt_enable();
 135 }