kernel/arch/arm64/kernel/efi.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/atomic.h>
  15 #include <linux/dmi.h>
  16 #include <linux/efi.h>
  17 #include <linux/export.h>
  18 #include <linux/memblock.h>
  19 #include <linux/mm_types.h>
  20 #include <linux/bootmem.h>
  21 #include <linux/of.h>
  22 #include <linux/of_fdt.h>
  23 #include <linux/preempt.h>
  24 #include <linux/rbtree.h>
  25 #include <linux/rwsem.h>
  26 #include <linux/sched.h>
  27 #include <linux/slab.h>
  28 #include <linux/spinlock.h>
  29
  30 #include <asm/cacheflush.h>
  31 #include <asm/efi.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/mmu_context.h>
  34 #include <asm/mmu.h>
  35 #include <asm/pgtable.h>
  36
  37 struct efi_memory_map memmap;
  38
  39 static u64 efi_system_table;
  40
  41 static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;
  42
  43 static struct mm_struct efi_mm = {
  44         .mm_rb                  = RB_ROOT,
  45         .pgd                    = efi_pgd,
  46         .mm_users               = ATOMIC_INIT(2),
  47         .mm_count               = ATOMIC_INIT(1),
  48         .mmap_sem               = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
  49         .page_table_lock        = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
  50         .mmlist                 = LIST_HEAD_INIT(efi_mm.mmlist),
  51 };
  52
  53 static int __init is_normal_ram(efi_memory_desc_t *md)
  54 {
  55         if (md->attribute & EFI_MEMORY_WB)
  56                 return 1;
  57         return 0;
  58 }
  59
  60 /*
  61  * Translate a EFI virtual address into a physical address: this is necessary,
  62  * as some data members of the EFI system table are virtually remapped after
  63  * SetVirtualAddressMap() has been called.
  64  */
  65 static phys_addr_t efi_to_phys(unsigned long addr)
  66 {
  67         efi_memory_desc_t *md;
  68
  69         for_each_efi_memory_desc(&memmap, md) {
  70                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  71                         continue;
  72                 if (md->virt_addr == 0)
  73                         /* no virtual mapping has been installed by the stub */
  74                         break;
  75                 if (md->virt_addr <= addr &&
  76                     (addr - md->virt_addr) < (md->num_pages << EFI_PAGE_SHIFT))
  77                         return md->phys_addr + addr - md->virt_addr;
  78         }
  79         return addr;
  80 }
  81
  82 static int __init uefi_init(void)
  83 {
  84         efi_char16_t *c16;
  85         void *config_tables;
  86         u64 table_size;
  87         char vendor[100] = "unknown";
  88         int i, retval;
  89
  90         efi.systab = early_memremap(efi_system_table,
  91                                     sizeof(efi_system_table_t));
  92         if (efi.systab == NULL) {
  93                 pr_warn("Unable to map EFI system table.\n");
  94                 return -ENOMEM;
  95         }
  96
  97         set_bit(EFI_BOOT, &efi.flags);
  98         set_bit(EFI_64BIT, &efi.flags);
  99
 100         /*
 101          * Verify the EFI Table
 102          */
 103         if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
 104                 pr_err("System table signature incorrect\n");
 105                 retval = -EINVAL;
 106                 goto out;
 107         }
 108         if ((efi.systab->hdr.revision >> 16) < 2)
 109                 pr_warn("Warning: EFI system table version %d.%02d, expected 2.00 or greater\n",
 110                         efi.systab->hdr.revision >> 16,
 111                         efi.systab->hdr.revision & 0xffff);
 112
 113         /* Show what we know for posterity */
 114         c16 = early_memremap(efi_to_phys(efi.systab->fw_vendor),
 115                              sizeof(vendor) * sizeof(efi_char16_t));
 116         if (c16) {
 117                 for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
 118                         vendor[i] = c16[i];
 119                 vendor[i] = '\0';
 120                 early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
 121         }
 122
 123         pr_info("EFI v%u.%.02u by %s\n",
 124                 efi.systab->hdr.revision >> 16,
 125                 efi.systab->hdr.revision & 0xffff, vendor);
 126
 127         table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
 128         config_tables = early_memremap(efi_to_phys(efi.systab->tables),
 129                                        table_size);
 130         if (config_tables == NULL) {
 131                 pr_warn("Unable to map EFI config table array.\n");
 132                 retval = -ENOMEM;
 133                 goto out;
 134         }
 135         retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
 136                                          sizeof(efi_config_table_64_t), NULL);
 137
 138         early_memunmap(config_tables, table_size);
 139 out:
 140         early_memunmap(efi.systab,  sizeof(efi_system_table_t));
 141         return retval;
 142 }
 143
 144 /*
 145  * Return true for RAM regions we want to permanently reserve.
 146  */
 147 static __init int is_reserve_region(efi_memory_desc_t *md)
 148 {
 149         switch (md->type) {
 150         case EFI_LOADER_CODE:
 151         case EFI_LOADER_DATA:
 152         case EFI_BOOT_SERVICES_CODE:
 153         case EFI_BOOT_SERVICES_DATA:
 154         case EFI_CONVENTIONAL_MEMORY:
 155         case EFI_PERSISTENT_MEMORY:
 156                 return 0;
 157         default:
 158                 break;
 159         }
 160         return is_normal_ram(md);
 161 }
 162
 163 static __init void reserve_regions(void)
 164 {
 165         efi_memory_desc_t *md;
 166         u64 paddr, npages, size;
 167
 168         if (efi_enabled(EFI_DBG))
 169                 pr_info("Processing EFI memory map:\n");
 170
 171         for_each_efi_memory_desc(&memmap, md) {
 172                 paddr = md->phys_addr;
 173                 npages = md->num_pages;
 174
 175                 if (efi_enabled(EFI_DBG)) {
 176                         char buf[64];
 177
 178                         pr_info("  0x%012llx-0x%012llx %s",
 179                                 paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
 180                                 efi_md_typeattr_format(buf, sizeof(buf), md));
 181                 }
 182
 183                 memrange_efi_to_native(&paddr, &npages);
 184                 size = npages << PAGE_SHIFT;
 185
 186                 if (is_normal_ram(md))
 187                         early_init_dt_add_memory_arch(paddr, size);
 188
 189                 if (is_reserve_region(md)) {
 190                         memblock_reserve(paddr, size);
 191                         if (efi_enabled(EFI_DBG))
 192                                 pr_cont("*");
 193                 }
 194
 195                 if (efi_enabled(EFI_DBG))
 196                         pr_cont("\n");
 197         }
 198
 199         set_bit(EFI_MEMMAP, &efi.flags);
 200 }
 201
 202 void __init efi_init(void)
 203 {
 204         struct efi_fdt_params params;
 205
 206         /* Grab UEFI information placed in FDT by stub */
 207         if (!efi_get_fdt_params(&params))
 208                 return;
 209
 210         efi_system_table = params.system_table;
 211
 212         memblock_reserve(params.mmap & PAGE_MASK,
 213                          PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
 214         memmap.phys_map = params.mmap;
 215         memmap.map = early_memremap(params.mmap, params.mmap_size);
 216         if (memmap.map == NULL) {
 217                 /*
 218                 * If we are booting via UEFI, the UEFI memory map is the only
 219                 * description of memory we have, so there is little point in
 220                 * proceeding if we cannot access it.
 221                 */
 222                 panic("Unable to map EFI memory map.\n");
 223         }
 224         memmap.map_end = memmap.map + params.mmap_size;
 225         memmap.desc_size = params.desc_size;
 226         memmap.desc_version = params.desc_ver;
 227
 228         if (uefi_init() < 0)
 229                 return;
 230
 231         reserve_regions();
 232         early_memunmap(memmap.map, params.mmap_size);
 233 }
 234
 235 static bool __init efi_virtmap_init(void)
 236 {
 237         efi_memory_desc_t *md;
 238
 239         init_new_context(NULL, &efi_mm);
 240
 241         for_each_efi_memory_desc(&memmap, md) {
 242                 pgprot_t prot;
 243
 244                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
 245                         continue;
 246                 if (md->virt_addr == 0)
 247                         return false;
 248
 249                 pr_info("  EFI remap 0x%016llx => %p\n",
 250                         md->phys_addr, (void *)md->virt_addr);
 251
 252                 /*
 253                  * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
 254                  * executable, everything else can be mapped with the XN bits
 255                  * set.
 256                  */
 257                 if (!is_normal_ram(md))
 258                         prot = __pgprot(PROT_DEVICE_nGnRE);
 259                 else if (md->type == EFI_RUNTIME_SERVICES_CODE ||
 260                          !PAGE_ALIGNED(md->phys_addr))
 261                         prot = PAGE_KERNEL_EXEC;
 262                 else
 263                         prot = PAGE_KERNEL;
 264
 265                 create_pgd_mapping(&efi_mm, md->phys_addr, md->virt_addr,
 266                                    md->num_pages << EFI_PAGE_SHIFT,
 267                                    __pgprot(pgprot_val(prot) | PTE_NG));
 268         }
 269         return true;
 270 }
 271
 272 /*
 273  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 274  * non-early mapping of the UEFI system table and virtual mappings for all
 275  * EFI_MEMORY_RUNTIME regions.
 276  */
 277 static int __init arm64_enable_runtime_services(void)
 278 {
 279         u64 mapsize;
 280
 281         if (!efi_enabled(EFI_BOOT)) {
 282                 pr_info("EFI services will not be available.\n");
 283                 return 0;
 284         }
 285
 286         if (efi_runtime_disabled()) {
 287                 pr_info("EFI runtime services will be disabled.\n");
 288                 return 0;
 289         }
 290
 291         pr_info("Remapping and enabling EFI services.\n");
 292
 293         mapsize = memmap.map_end - memmap.map;
 294         memmap.map = (__force void *)ioremap_cache(memmap.phys_map,
 295                                                    mapsize);
 296         if (!memmap.map) {
 297                 pr_err("Failed to remap EFI memory map\n");
 298                 return -ENOMEM;
 299         }
 300         memmap.map_end = memmap.map + mapsize;
 301         efi.memmap = &memmap;
 302
 303         efi.systab = (__force void *)ioremap_cache(efi_system_table,
 304                                                    sizeof(efi_system_table_t));
 305         if (!efi.systab) {
 306                 pr_err("Failed to remap EFI System Table\n");
 307                 return -ENOMEM;
 308         }
 309         set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 310
 311         if (!efi_virtmap_init()) {
 312                 pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 313                 return -ENOMEM;
 314         }
 315
 316         /* Set up runtime services function pointers */
 317         efi_native_runtime_setup();
 318         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 319
 320         efi.runtime_version = efi.systab->hdr.revision;
 321
 322         return 0;
 323 }
 324 early_initcall(arm64_enable_runtime_services);
 325
 326 static int __init arm64_dmi_init(void)
 327 {
 328         /*
 329          * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
 330          * be called early because dmi_id_init(), which is an arch_initcall
 331          * itself, depends on dmi_scan_machine() having been called already.
 332          */
 333         dmi_scan_machine();
 334         if (dmi_available)
 335                 dmi_set_dump_stack_arch_desc();
 336         return 0;
 337 }
 338 core_initcall(arm64_dmi_init);
 339
 340 static void efi_set_pgd(struct mm_struct *mm)
 341 {
 342         switch_mm(NULL, mm, NULL);
 343 }
 344
 345 void efi_virtmap_load(void)
 346 {
 347         preempt_disable();
 348         efi_set_pgd(&efi_mm);
 349 }
 350
 351 void efi_virtmap_unload(void)
 352 {
 353         efi_set_pgd(current->active_mm);
 354         preempt_enable();
 355 }
 356
 357 /*
 358  * UpdateCapsule() depends on the system being shutdown via
 359  * ResetSystem().
 360  */
 361 bool efi_poweroff_required(void)
 362 {
 363         return efi_enabled(EFI_RUNTIME_SERVICES);
 364 }