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         INIT_MM_CONTEXT(efi_mm)
  52 };
  53
  54 static int __init is_normal_ram(efi_memory_desc_t *md)
  55 {
  56         if (md->attribute & EFI_MEMORY_WB)
  57                 return 1;
  58         return 0;
  59 }
  60
  61 /*
  62  * Translate a EFI virtual address into a physical address: this is necessary,
  63  * as some data members of the EFI system table are virtually remapped after
  64  * SetVirtualAddressMap() has been called.
  65  */
  66 static phys_addr_t efi_to_phys(unsigned long addr)
  67 {
  68         efi_memory_desc_t *md;
  69
  70         for_each_efi_memory_desc(&memmap, md) {
  71                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  72                         continue;
  73                 if (md->virt_addr == 0)
  74                         /* no virtual mapping has been installed by the stub */
  75                         break;
  76                 if (md->virt_addr <= addr &&
  77                     (addr - md->virt_addr) < (md->num_pages << EFI_PAGE_SHIFT))
  78                         return md->phys_addr + addr - md->virt_addr;
  79         }
  80         return addr;
  81 }
  82
  83 static int __init uefi_init(void)
  84 {
  85         efi_char16_t *c16;
  86         void *config_tables;
  87         u64 table_size;
  88         char vendor[100] = "unknown";
  89         int i, retval;
  90
  91         efi.systab = early_memremap(efi_system_table,
  92                                     sizeof(efi_system_table_t));
  93         if (efi.systab == NULL) {
  94                 pr_warn("Unable to map EFI system table.\n");
  95                 return -ENOMEM;
  96         }
  97
  98         set_bit(EFI_BOOT, &efi.flags);
  99         set_bit(EFI_64BIT, &efi.flags);
 100
 101         /*
 102          * Verify the EFI Table
 103          */
 104         if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
 105                 pr_err("System table signature incorrect\n");
 106                 retval = -EINVAL;
 107                 goto out;
 108         }
 109         if ((efi.systab->hdr.revision >> 16) < 2)
 110                 pr_warn("Warning: EFI system table version %d.%02d, expected 2.00 or greater\n",
 111                         efi.systab->hdr.revision >> 16,
 112                         efi.systab->hdr.revision & 0xffff);
 113
 114         /* Show what we know for posterity */
 115         c16 = early_memremap(efi_to_phys(efi.systab->fw_vendor),
 116                              sizeof(vendor) * sizeof(efi_char16_t));
 117         if (c16) {
 118                 for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
 119                         vendor[i] = c16[i];
 120                 vendor[i] = '\0';
 121                 early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
 122         }
 123
 124         pr_info("EFI v%u.%.02u by %s\n",
 125                 efi.systab->hdr.revision >> 16,
 126                 efi.systab->hdr.revision & 0xffff, vendor);
 127
 128         table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
 129         config_tables = early_memremap(efi_to_phys(efi.systab->tables),
 130                                        table_size);
 131
 132         retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
 133                                          sizeof(efi_config_table_64_t), NULL);
 134
 135         early_memunmap(config_tables, table_size);
 136 out:
 137         early_memunmap(efi.systab,  sizeof(efi_system_table_t));
 138         return retval;
 139 }
 140
 141 /*
 142  * Return true for RAM regions we want to permanently reserve.
 143  */
 144 static __init int is_reserve_region(efi_memory_desc_t *md)
 145 {
 146         switch (md->type) {
 147         case EFI_LOADER_CODE:
 148         case EFI_LOADER_DATA:
 149         case EFI_BOOT_SERVICES_CODE:
 150         case EFI_BOOT_SERVICES_DATA:
 151         case EFI_CONVENTIONAL_MEMORY:
 152         case EFI_PERSISTENT_MEMORY:
 153                 return 0;
 154         default:
 155                 break;
 156         }
 157         return is_normal_ram(md);
 158 }
 159
 160 static __init void reserve_regions(void)
 161 {
 162         efi_memory_desc_t *md;
 163         u64 paddr, npages, size;
 164
 165         if (efi_enabled(EFI_DBG))
 166                 pr_info("Processing EFI memory map:\n");
 167
 168         for_each_efi_memory_desc(&memmap, md) {
 169                 paddr = md->phys_addr;
 170                 npages = md->num_pages;
 171
 172                 if (efi_enabled(EFI_DBG)) {
 173                         char buf[64];
 174
 175                         pr_info("  0x%012llx-0x%012llx %s",
 176                                 paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
 177                                 efi_md_typeattr_format(buf, sizeof(buf), md));
 178                 }
 179
 180                 memrange_efi_to_native(&paddr, &npages);
 181                 size = npages << PAGE_SHIFT;
 182
 183                 if (is_normal_ram(md))
 184                         early_init_dt_add_memory_arch(paddr, size);
 185
 186                 if (is_reserve_region(md)) {
 187                         memblock_reserve(paddr, size);
 188                         if (efi_enabled(EFI_DBG))
 189                                 pr_cont("*");
 190                 }
 191
 192                 if (efi_enabled(EFI_DBG))
 193                         pr_cont("\n");
 194         }
 195
 196         set_bit(EFI_MEMMAP, &efi.flags);
 197 }
 198
 199 void __init efi_init(void)
 200 {
 201         struct efi_fdt_params params;
 202
 203         /* Grab UEFI information placed in FDT by stub */
 204         if (!efi_get_fdt_params(&params))
 205                 return;
 206
 207         efi_system_table = params.system_table;
 208
 209         memblock_reserve(params.mmap & PAGE_MASK,
 210                          PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
 211         memmap.phys_map = params.mmap;
 212         memmap.map = early_memremap(params.mmap, params.mmap_size);
 213         memmap.map_end = memmap.map + params.mmap_size;
 214         memmap.desc_size = params.desc_size;
 215         memmap.desc_version = params.desc_ver;
 216
 217         if (uefi_init() < 0)
 218                 return;
 219
 220         reserve_regions();
 221         early_memunmap(memmap.map, params.mmap_size);
 222 }
 223
 224 static bool __init efi_virtmap_init(void)
 225 {
 226         efi_memory_desc_t *md;
 227
 228         for_each_efi_memory_desc(&memmap, md) {
 229                 u64 paddr, npages, size;
 230                 pgprot_t prot;
 231
 232                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
 233                         continue;
 234                 if (md->virt_addr == 0)
 235                         return false;
 236
 237                 paddr = md->phys_addr;
 238                 npages = md->num_pages;
 239                 memrange_efi_to_native(&paddr, &npages);
 240                 size = npages << PAGE_SHIFT;
 241
 242                 pr_info("  EFI remap 0x%016llx => %p\n",
 243                         md->phys_addr, (void *)md->virt_addr);
 244
 245                 /*
 246                  * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
 247                  * executable, everything else can be mapped with the XN bits
 248                  * set.
 249                  */
 250                 if (!is_normal_ram(md))
 251                         prot = __pgprot(PROT_DEVICE_nGnRE);
 252                 else if (md->type == EFI_RUNTIME_SERVICES_CODE ||
 253                          !PAGE_ALIGNED(md->phys_addr))
 254                         prot = PAGE_KERNEL_EXEC;
 255                 else
 256                         prot = PAGE_KERNEL;
 257
 258                 create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
 259         }
 260         return true;
 261 }
 262
 263 /*
 264  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 265  * non-early mapping of the UEFI system table and virtual mappings for all
 266  * EFI_MEMORY_RUNTIME regions.
 267  */
 268 static int __init arm64_enable_runtime_services(void)
 269 {
 270         u64 mapsize;
 271
 272         if (!efi_enabled(EFI_BOOT)) {
 273                 pr_info("EFI services will not be available.\n");
 274                 return -1;
 275         }
 276
 277         if (efi_runtime_disabled()) {
 278                 pr_info("EFI runtime services will be disabled.\n");
 279                 return -1;
 280         }
 281
 282         pr_info("Remapping and enabling EFI services.\n");
 283
 284         mapsize = memmap.map_end - memmap.map;
 285         memmap.map = (__force void *)ioremap_cache(memmap.phys_map,
 286                                                    mapsize);
 287         if (!memmap.map) {
 288                 pr_err("Failed to remap EFI memory map\n");
 289                 return -1;
 290         }
 291         memmap.map_end = memmap.map + mapsize;
 292         efi.memmap = &memmap;
 293
 294         efi.systab = (__force void *)ioremap_cache(efi_system_table,
 295                                                    sizeof(efi_system_table_t));
 296         if (!efi.systab) {
 297                 pr_err("Failed to remap EFI System Table\n");
 298                 return -1;
 299         }
 300         set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 301
 302         if (!efi_virtmap_init()) {
 303                 pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 304                 return -1;
 305         }
 306
 307         /* Set up runtime services function pointers */
 308         efi_native_runtime_setup();
 309         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 310
 311         efi.runtime_version = efi.systab->hdr.revision;
 312
 313         return 0;
 314 }
 315 early_initcall(arm64_enable_runtime_services);
 316
 317 static int __init arm64_dmi_init(void)
 318 {
 319         /*
 320          * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
 321          * be called early because dmi_id_init(), which is an arch_initcall
 322          * itself, depends on dmi_scan_machine() having been called already.
 323          */
 324         dmi_scan_machine();
 325         if (dmi_available)
 326                 dmi_set_dump_stack_arch_desc();
 327         return 0;
 328 }
 329 core_initcall(arm64_dmi_init);
 330
 331 static void efi_set_pgd(struct mm_struct *mm)
 332 {
 333         if (mm == &init_mm)
 334                 cpu_set_reserved_ttbr0();
 335         else
 336                 cpu_switch_mm(mm->pgd, mm);
 337
 338         flush_tlb_all();
 339         if (icache_is_aivivt())
 340                 __flush_icache_all();
 341 }
 342
 343 void efi_virtmap_load(void)
 344 {
 345         preempt_disable();
 346         efi_set_pgd(&efi_mm);
 347 }
 348
 349 void efi_virtmap_unload(void)
 350 {
 351         efi_set_pgd(current->active_mm);
 352         preempt_enable();
 353 }
 354
 355 /*
 356  * UpdateCapsule() depends on the system being shutdown via
 357  * ResetSystem().
 358  */
 359 bool efi_poweroff_required(void)
 360 {
 361         return efi_enabled(EFI_RUNTIME_SERVICES);
 362 }