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 uefi_debug __initdata;
  55 static int __init uefi_debug_setup(char *str)
  56 {
  57         uefi_debug = 1;
  58
  59         return 0;
  60 }
  61 early_param("uefi_debug", uefi_debug_setup);
  62
  63 static int __init is_normal_ram(efi_memory_desc_t *md)
  64 {
  65         if (md->attribute & EFI_MEMORY_WB)
  66                 return 1;
  67         return 0;
  68 }
  69
  70 /*
  71  * Translate a EFI virtual address into a physical address: this is necessary,
  72  * as some data members of the EFI system table are virtually remapped after
  73  * SetVirtualAddressMap() has been called.
  74  */
  75 static phys_addr_t efi_to_phys(unsigned long addr)
  76 {
  77         efi_memory_desc_t *md;
  78
  79         for_each_efi_memory_desc(&memmap, md) {
  80                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
  81                         continue;
  82                 if (md->virt_addr == 0)
  83                         /* no virtual mapping has been installed by the stub */
  84                         break;
  85                 if (md->virt_addr <= addr &&
  86                     (addr - md->virt_addr) < (md->num_pages << EFI_PAGE_SHIFT))
  87                         return md->phys_addr + addr - md->virt_addr;
  88         }
  89         return addr;
  90 }
  91
  92 static int __init uefi_init(void)
  93 {
  94         efi_char16_t *c16;
  95         void *config_tables;
  96         u64 table_size;
  97         char vendor[100] = "unknown";
  98         int i, retval;
  99
 100         efi.systab = early_memremap(efi_system_table,
 101                                     sizeof(efi_system_table_t));
 102         if (efi.systab == NULL) {
 103                 pr_warn("Unable to map EFI system table.\n");
 104                 return -ENOMEM;
 105         }
 106
 107         set_bit(EFI_BOOT, &efi.flags);
 108         set_bit(EFI_64BIT, &efi.flags);
 109
 110         /*
 111          * Verify the EFI Table
 112          */
 113         if (efi.systab->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
 114                 pr_err("System table signature incorrect\n");
 115                 retval = -EINVAL;
 116                 goto out;
 117         }
 118         if ((efi.systab->hdr.revision >> 16) < 2)
 119                 pr_warn("Warning: EFI system table version %d.%02d, expected 2.00 or greater\n",
 120                         efi.systab->hdr.revision >> 16,
 121                         efi.systab->hdr.revision & 0xffff);
 122
 123         /* Show what we know for posterity */
 124         c16 = early_memremap(efi_to_phys(efi.systab->fw_vendor),
 125                              sizeof(vendor) * sizeof(efi_char16_t));
 126         if (c16) {
 127                 for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
 128                         vendor[i] = c16[i];
 129                 vendor[i] = '\0';
 130                 early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
 131         }
 132
 133         pr_info("EFI v%u.%.02u by %s\n",
 134                 efi.systab->hdr.revision >> 16,
 135                 efi.systab->hdr.revision & 0xffff, vendor);
 136
 137         table_size = sizeof(efi_config_table_64_t) * efi.systab->nr_tables;
 138         config_tables = early_memremap(efi_to_phys(efi.systab->tables),
 139                                        table_size);
 140
 141         retval = efi_config_parse_tables(config_tables, efi.systab->nr_tables,
 142                                          sizeof(efi_config_table_64_t), NULL);
 143
 144         early_memunmap(config_tables, table_size);
 145 out:
 146         early_memunmap(efi.systab,  sizeof(efi_system_table_t));
 147         return retval;
 148 }
 149
 150 /*
 151  * Return true for RAM regions we want to permanently reserve.
 152  */
 153 static __init int is_reserve_region(efi_memory_desc_t *md)
 154 {
 155         switch (md->type) {
 156         case EFI_LOADER_CODE:
 157         case EFI_LOADER_DATA:
 158         case EFI_BOOT_SERVICES_CODE:
 159         case EFI_BOOT_SERVICES_DATA:
 160         case EFI_CONVENTIONAL_MEMORY:
 161         case EFI_PERSISTENT_MEMORY:
 162                 return 0;
 163         default:
 164                 break;
 165         }
 166         return is_normal_ram(md);
 167 }
 168
 169 static __init void reserve_regions(void)
 170 {
 171         efi_memory_desc_t *md;
 172         u64 paddr, npages, size;
 173
 174         if (uefi_debug)
 175                 pr_info("Processing EFI memory map:\n");
 176
 177         for_each_efi_memory_desc(&memmap, md) {
 178                 paddr = md->phys_addr;
 179                 npages = md->num_pages;
 180
 181                 if (uefi_debug) {
 182                         char buf[64];
 183
 184                         pr_info("  0x%012llx-0x%012llx %s",
 185                                 paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
 186                                 efi_md_typeattr_format(buf, sizeof(buf), md));
 187                 }
 188
 189                 memrange_efi_to_native(&paddr, &npages);
 190                 size = npages << PAGE_SHIFT;
 191
 192                 if (is_normal_ram(md))
 193                         early_init_dt_add_memory_arch(paddr, size);
 194
 195                 if (is_reserve_region(md)) {
 196                         memblock_reserve(paddr, size);
 197                         if (uefi_debug)
 198                                 pr_cont("*");
 199                 }
 200
 201                 if (uefi_debug)
 202                         pr_cont("\n");
 203         }
 204
 205         set_bit(EFI_MEMMAP, &efi.flags);
 206 }
 207
 208 void __init efi_init(void)
 209 {
 210         struct efi_fdt_params params;
 211
 212         /* Grab UEFI information placed in FDT by stub */
 213         if (!efi_get_fdt_params(&params, uefi_debug))
 214                 return;
 215
 216         efi_system_table = params.system_table;
 217
 218         memblock_reserve(params.mmap & PAGE_MASK,
 219                          PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
 220         memmap.phys_map = (void *)params.mmap;
 221         memmap.map = early_memremap(params.mmap, params.mmap_size);
 222         memmap.map_end = memmap.map + params.mmap_size;
 223         memmap.desc_size = params.desc_size;
 224         memmap.desc_version = params.desc_ver;
 225
 226         if (uefi_init() < 0)
 227                 return;
 228
 229         reserve_regions();
 230         early_memunmap(memmap.map, params.mmap_size);
 231 }
 232
 233 static bool __init efi_virtmap_init(void)
 234 {
 235         efi_memory_desc_t *md;
 236
 237         for_each_efi_memory_desc(&memmap, md) {
 238                 u64 paddr, npages, size;
 239                 pgprot_t prot;
 240
 241                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
 242                         continue;
 243                 if (md->virt_addr == 0)
 244                         return false;
 245
 246                 paddr = md->phys_addr;
 247                 npages = md->num_pages;
 248                 memrange_efi_to_native(&paddr, &npages);
 249                 size = npages << PAGE_SHIFT;
 250
 251                 pr_info("  EFI remap 0x%016llx => %p\n",
 252                         md->phys_addr, (void *)md->virt_addr);
 253
 254                 /*
 255                  * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
 256                  * executable, everything else can be mapped with the XN bits
 257                  * set.
 258                  */
 259                 if (!is_normal_ram(md))
 260                         prot = __pgprot(PROT_DEVICE_nGnRE);
 261                 else if (md->type == EFI_RUNTIME_SERVICES_CODE)
 262                         prot = PAGE_KERNEL_EXEC;
 263                 else
 264                         prot = PAGE_KERNEL;
 265
 266                 create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
 267         }
 268         return true;
 269 }
 270
 271 /*
 272  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 273  * non-early mapping of the UEFI system table and virtual mappings for all
 274  * EFI_MEMORY_RUNTIME regions.
 275  */
 276 static int __init arm64_enable_runtime_services(void)
 277 {
 278         u64 mapsize;
 279
 280         if (!efi_enabled(EFI_BOOT)) {
 281                 pr_info("EFI services will not be available.\n");
 282                 return -1;
 283         }
 284
 285         if (efi_runtime_disabled()) {
 286                 pr_info("EFI runtime services will be disabled.\n");
 287                 return -1;
 288         }
 289
 290         pr_info("Remapping and enabling EFI services.\n");
 291
 292         mapsize = memmap.map_end - memmap.map;
 293         memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
 294                                                    mapsize);
 295         if (!memmap.map) {
 296                 pr_err("Failed to remap EFI memory map\n");
 297                 return -1;
 298         }
 299         memmap.map_end = memmap.map + mapsize;
 300         efi.memmap = &memmap;
 301
 302         efi.systab = (__force void *)ioremap_cache(efi_system_table,
 303                                                    sizeof(efi_system_table_t));
 304         if (!efi.systab) {
 305                 pr_err("Failed to remap EFI System Table\n");
 306                 return -1;
 307         }
 308         set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 309
 310         if (!efi_virtmap_init()) {
 311                 pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 312                 return -1;
 313         }
 314
 315         /* Set up runtime services function pointers */
 316         efi_native_runtime_setup();
 317         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 318
 319         efi.runtime_version = efi.systab->hdr.revision;
 320
 321         return 0;
 322 }
 323 early_initcall(arm64_enable_runtime_services);
 324
 325 static int __init arm64_dmi_init(void)
 326 {
 327         /*
 328          * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
 329          * be called early because dmi_id_init(), which is an arch_initcall
 330          * itself, depends on dmi_scan_machine() having been called already.
 331          */
 332         dmi_scan_machine();
 333         if (dmi_available)
 334                 dmi_set_dump_stack_arch_desc();
 335         return 0;
 336 }
 337 core_initcall(arm64_dmi_init);
 338
 339 static void efi_set_pgd(struct mm_struct *mm)
 340 {
 341         if (mm == &init_mm)
 342                 cpu_set_reserved_ttbr0();
 343         else
 344                 cpu_switch_mm(mm->pgd, mm);
 345
 346         flush_tlb_all();
 347         if (icache_is_aivivt())
 348                 __flush_icache_all();
 349 }
 350
 351 void efi_virtmap_load(void)
 352 {
 353         preempt_disable();
 354         efi_set_pgd(&efi_mm);
 355 }
 356
 357 void efi_virtmap_unload(void)
 358 {
 359         efi_set_pgd(current->active_mm);
 360         preempt_enable();
 361 }
 362
 363 /*
 364  * UpdateCapsule() depends on the system being shutdown via
 365  * ResetSystem().
 366  */
 367 bool efi_poweroff_required(void)
 368 {
 369         return efi_enabled(EFI_RUNTIME_SERVICES);
 370 }