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 bool systab_found; 46 47 efi_mm.pgd = pgd_alloc(&efi_mm); 48 init_new_context(NULL, &efi_mm); 49 50 systab_found = false; 51 for_each_efi_memory_desc(md) { 52 phys_addr_t phys = md->phys_addr; 53 int ret; 54 55 if (!(md->attribute & EFI_MEMORY_RUNTIME)) 56 continue; 57 if (md->virt_addr == 0) 58 return false; 59 60 ret = efi_create_mapping(&efi_mm, md); 61 if (!ret) { 62 pr_info(" EFI remap %pa => %p\n", 63 &phys, (void *)(unsigned long)md->virt_addr); 64 } else { 65 pr_warn(" EFI remap %pa: failed to create mapping (%d)\n", 66 &phys, ret); 67 return false; 68 } 69 /* 70 * If this entry covers the address of the UEFI system table, 71 * calculate and record its virtual address. 72 */ 73 if (efi_system_table >= phys && 74 efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) { 75 efi.systab = (void *)(unsigned long)(efi_system_table - 76 phys + md->virt_addr); 77 systab_found = true; 78 } 79 } 80 if (!systab_found) { 81 pr_err("No virtual mapping found for the UEFI System Table\n"); 82 return false; 83 } 84 85 if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions)) 86 return false; 87 88 return true; 89 } 90 91 /* 92 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e., 93 * non-early mapping of the UEFI system table and virtual mappings for all 94 * EFI_MEMORY_RUNTIME regions. 95 */ 96 static int __init arm_enable_runtime_services(void) 97 { 98 u64 mapsize; 99 100 if (!efi_enabled(EFI_BOOT)) { 101 pr_info("EFI services will not be available.\n"); 102 return 0; 103 } 104 105 if (efi_runtime_disabled()) { 106 pr_info("EFI runtime services will be disabled.\n"); 107 return 0; 108 } 109 110 if (efi_enabled(EFI_RUNTIME_SERVICES)) { 111 pr_info("EFI runtime services access via paravirt.\n"); 112 return 0; 113 } 114 115 pr_info("Remapping and enabling EFI services.\n"); 116 117 mapsize = efi.memmap.map_end - efi.memmap.map; 118 119 efi.memmap.map = memremap(efi.memmap.phys_map, mapsize, MEMREMAP_WB); 120 if (!efi.memmap.map) { 121 pr_err("Failed to remap EFI memory map\n"); 122 return -ENOMEM; 123 } 124 efi.memmap.map_end = efi.memmap.map + mapsize; 125 126 if (!efi_virtmap_init()) { 127 pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n"); 128 return -ENOMEM; 129 } 130 131 /* Set up runtime services function pointers */ 132 efi_native_runtime_setup(); 133 set_bit(EFI_RUNTIME_SERVICES, &efi.flags); 134 135 return 0; 136 } 137 early_initcall(arm_enable_runtime_services); 138 139 void efi_virtmap_load(void) 140 { 141 preempt_disable(); 142 efi_set_pgd(&efi_mm); 143 } 144 145 void efi_virtmap_unload(void) 146 { 147 efi_set_pgd(current->active_mm); 148 preempt_enable(); 149 } 150