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
 131         retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
 132                                          sizeof(efi_config_table_64_t), NULL);
 133
 134         early_memunmap(config_tables, table_size);
 135 out:
 136         early_memunmap(efi.systab,  sizeof(efi_system_table_t));
 137         return retval;
 138 }
 139
 140 /*
 141  * Return true for RAM regions we want to permanently reserve.
 142  */
 143 static __init int is_reserve_region(efi_memory_desc_t *md)
 144 {
 145         switch (md->type) {
 146         case EFI_LOADER_CODE:
 147         case EFI_LOADER_DATA:
 148         case EFI_BOOT_SERVICES_CODE:
 149         case EFI_BOOT_SERVICES_DATA:
 150         case EFI_CONVENTIONAL_MEMORY:
 151         case EFI_PERSISTENT_MEMORY:
 152                 return 0;
 153         default:
 154                 break;
 155         }
 156         return is_normal_ram(md);
 157 }
 158
 159 static __init void reserve_regions(void)
 160 {
 161         efi_memory_desc_t *md;
 162         u64 paddr, npages, size;
 163
 164         if (efi_enabled(EFI_DBG))
 165                 pr_info("Processing EFI memory map:\n");
 166
 167         for_each_efi_memory_desc(&memmap, md) {
 168                 paddr = md->phys_addr;
 169                 npages = md->num_pages;
 170
 171                 if (efi_enabled(EFI_DBG)) {
 172                         char buf[64];
 173
 174                         pr_info("  0x%012llx-0x%012llx %s",
 175                                 paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
 176                                 efi_md_typeattr_format(buf, sizeof(buf), md));
 177                 }
 178
 179                 memrange_efi_to_native(&paddr, &npages);
 180                 size = npages << PAGE_SHIFT;
 181
 182                 if (is_normal_ram(md))
 183                         early_init_dt_add_memory_arch(paddr, size);
 184
 185                 if (is_reserve_region(md)) {
 186                         memblock_reserve(paddr, size);
 187                         if (efi_enabled(EFI_DBG))
 188                                 pr_cont("*");
 189                 }
 190
 191                 if (efi_enabled(EFI_DBG))
 192                         pr_cont("\n");
 193         }
 194
 195         set_bit(EFI_MEMMAP, &efi.flags);
 196 }
 197
 198 void __init efi_init(void)
 199 {
 200         struct efi_fdt_params params;
 201
 202         /* Grab UEFI information placed in FDT by stub */
 203         if (!efi_get_fdt_params(&params))
 204                 return;
 205
 206         efi_system_table = params.system_table;
 207
 208         memblock_reserve(params.mmap & PAGE_MASK,
 209                          PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
 210         memmap.phys_map = params.mmap;
 211         memmap.map = early_memremap(params.mmap, params.mmap_size);
 212         memmap.map_end = memmap.map + params.mmap_size;
 213         memmap.desc_size = params.desc_size;
 214         memmap.desc_version = params.desc_ver;
 215
 216         if (uefi_init() < 0)
 217                 return;
 218
 219         reserve_regions();
 220         early_memunmap(memmap.map, params.mmap_size);
 221 }
 222
 223 static bool __init efi_virtmap_init(void)
 224 {
 225         efi_memory_desc_t *md;
 226
 227         for_each_efi_memory_desc(&memmap, md) {
 228                 u64 paddr, npages, size;
 229                 pgprot_t prot;
 230
 231                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
 232                         continue;
 233                 if (md->virt_addr == 0)
 234                         return false;
 235
 236                 paddr = md->phys_addr;
 237                 npages = md->num_pages;
 238                 memrange_efi_to_native(&paddr, &npages);
 239                 size = npages << PAGE_SHIFT;
 240
 241                 pr_info("  EFI remap 0x%016llx => %p\n",
 242                         md->phys_addr, (void *)md->virt_addr);
 243
 244                 /*
 245                  * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
 246                  * executable, everything else can be mapped with the XN bits
 247                  * set.
 248                  */
 249                 if (!is_normal_ram(md))
 250                         prot = __pgprot(PROT_DEVICE_nGnRE);
 251                 else if (md->type == EFI_RUNTIME_SERVICES_CODE ||
 252                          !PAGE_ALIGNED(md->phys_addr))
 253                         prot = PAGE_KERNEL_EXEC;
 254                 else
 255                         prot = PAGE_KERNEL;
 256
 257                 create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
 258         }
 259         return true;
 260 }
 261
 262 /*
 263  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 264  * non-early mapping of the UEFI system table and virtual mappings for all
 265  * EFI_MEMORY_RUNTIME regions.
 266  */
 267 static int __init arm64_enable_runtime_services(void)
 268 {
 269         u64 mapsize;
 270
 271         if (!efi_enabled(EFI_BOOT)) {
 272                 pr_info("EFI services will not be available.\n");
 273                 return -1;
 274         }
 275
 276         if (efi_runtime_disabled()) {
 277                 pr_info("EFI runtime services will be disabled.\n");
 278                 return -1;
 279         }
 280
 281         pr_info("Remapping and enabling EFI services.\n");
 282
 283         mapsize = memmap.map_end - memmap.map;
 284         memmap.map = (__force void *)ioremap_cache(memmap.phys_map,
 285                                                    mapsize);
 286         if (!memmap.map) {
 287                 pr_err("Failed to remap EFI memory map\n");
 288                 return -1;
 289         }
 290         memmap.map_end = memmap.map + mapsize;
 291         efi.memmap = &memmap;
 292
 293         efi.systab = (__force void *)ioremap_cache(efi_system_table,
 294                                                    sizeof(efi_system_table_t));
 295         if (!efi.systab) {
 296                 pr_err("Failed to remap EFI System Table\n");
 297                 return -1;
 298         }
 299         set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 300
 301         if (!efi_virtmap_init()) {
 302                 pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 303                 return -1;
 304         }
 305
 306         /* Set up runtime services function pointers */
 307         efi_native_runtime_setup();
 308         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 309
 310         efi.runtime_version = efi.systab->hdr.revision;
 311
 312         return 0;
 313 }
 314 early_initcall(arm64_enable_runtime_services);
 315
 316 static int __init arm64_dmi_init(void)
 317 {
 318         /*
 319          * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
 320          * be called early because dmi_id_init(), which is an arch_initcall
 321          * itself, depends on dmi_scan_machine() having been called already.
 322          */
 323         dmi_scan_machine();
 324         if (dmi_available)
 325                 dmi_set_dump_stack_arch_desc();
 326         return 0;
 327 }
 328 core_initcall(arm64_dmi_init);
 329
 330 static void efi_set_pgd(struct mm_struct *mm)
 331 {
 332         if (mm == &init_mm)
 333                 cpu_set_reserved_ttbr0();
 334         else
 335                 cpu_switch_mm(mm->pgd, mm);
 336
 337         local_flush_tlb_all();
 338         if (icache_is_aivivt())
 339                 __local_flush_icache_all();
 340 }
 341
 342 void efi_virtmap_load(void)
 343 {
 344         preempt_disable();
 345         efi_set_pgd(&efi_mm);
 346 }
 347
 348 void efi_virtmap_unload(void)
 349 {
 350         efi_set_pgd(current->active_mm);
 351         preempt_enable();
 352 }
 353
 354 /*
 355  * UpdateCapsule() depends on the system being shutdown via
 356  * ResetSystem().
 357  */
 358 bool efi_poweroff_required(void)
 359 {
 360         return efi_enabled(EFI_RUNTIME_SERVICES);
 361 }