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