drivers/firmware/efi/libstub/arm-stub.c

   1 /*
   2  * EFI stub implementation that is shared by arm and arm64 architectures.
   3  * This should be #included by the EFI stub implementation files.
   4  *
   5  * Copyright (C) 2013,2014 Linaro Limited
   6  *     Roy Franz <roy.franz@linaro.org
   7  * Copyright (C) 2013 Red Hat, Inc.
   8  *     Mark Salter <msalter@redhat.com>
   9  *
  10  * This file is part of the Linux kernel, and is made available under the
  11  * terms of the GNU General Public License version 2.
  12  *
  13  */
  14
  15 #include <linux/efi.h>
  16 #include <linux/sort.h>
  17 #include <asm/efi.h>
  18
  19 #include "efistub.h"
  20
  21 bool __nokaslr;
  22
  23 static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
  24 {
  25         static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
  26         static efi_char16_t const var_name[] = {
  27                 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
  28
  29         efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
  30         unsigned long size = sizeof(u8);
  31         efi_status_t status;
  32         u8 val;
  33
  34         status = f_getvar((efi_char16_t *)var_name, (efi_guid_t *)&var_guid,
  35                           NULL, &size, &val);
  36
  37         switch (status) {
  38         case EFI_SUCCESS:
  39                 return val;
  40         case EFI_NOT_FOUND:
  41                 return 0;
  42         default:
  43                 return 1;
  44         }
  45 }
  46
  47 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
  48                              void *__image, void **__fh)
  49 {
  50         efi_file_io_interface_t *io;
  51         efi_loaded_image_t *image = __image;
  52         efi_file_handle_t *fh;
  53         efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
  54         efi_status_t status;
  55         void *handle = (void *)(unsigned long)image->device_handle;
  56
  57         status = sys_table_arg->boottime->handle_protocol(handle,
  58                                  &fs_proto, (void **)&io);
  59         if (status != EFI_SUCCESS) {
  60                 efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
  61                 return status;
  62         }
  63
  64         status = io->open_volume(io, &fh);
  65         if (status != EFI_SUCCESS)
  66                 efi_printk(sys_table_arg, "Failed to open volume\n");
  67
  68         *__fh = fh;
  69         return status;
  70 }
  71
  72 efi_status_t efi_file_close(void *handle)
  73 {
  74         efi_file_handle_t *fh = handle;
  75
  76         return fh->close(handle);
  77 }
  78
  79 efi_status_t
  80 efi_file_read(void *handle, unsigned long *size, void *addr)
  81 {
  82         efi_file_handle_t *fh = handle;
  83
  84         return fh->read(handle, size, addr);
  85 }
  86
  87
  88 efi_status_t
  89 efi_file_size(efi_system_table_t *sys_table_arg, void *__fh,
  90               efi_char16_t *filename_16, void **handle, u64 *file_sz)
  91 {
  92         efi_file_handle_t *h, *fh = __fh;
  93         efi_file_info_t *info;
  94         efi_status_t status;
  95         efi_guid_t info_guid = EFI_FILE_INFO_ID;
  96         unsigned long info_sz;
  97
  98         status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, (u64)0);
  99         if (status != EFI_SUCCESS) {
 100                 efi_printk(sys_table_arg, "Failed to open file: ");
 101                 efi_char16_printk(sys_table_arg, filename_16);
 102                 efi_printk(sys_table_arg, "\n");
 103                 return status;
 104         }
 105
 106         *handle = h;
 107
 108         info_sz = 0;
 109         status = h->get_info(h, &info_guid, &info_sz, NULL);
 110         if (status != EFI_BUFFER_TOO_SMALL) {
 111                 efi_printk(sys_table_arg, "Failed to get file info size\n");
 112                 return status;
 113         }
 114
 115 grow:
 116         status = sys_table_arg->boottime->allocate_pool(EFI_LOADER_DATA,
 117                                  info_sz, (void **)&info);
 118         if (status != EFI_SUCCESS) {
 119                 efi_printk(sys_table_arg, "Failed to alloc mem for file info\n");
 120                 return status;
 121         }
 122
 123         status = h->get_info(h, &info_guid, &info_sz,
 124                                                    info);
 125         if (status == EFI_BUFFER_TOO_SMALL) {
 126                 sys_table_arg->boottime->free_pool(info);
 127                 goto grow;
 128         }
 129
 130         *file_sz = info->file_size;
 131         sys_table_arg->boottime->free_pool(info);
 132
 133         if (status != EFI_SUCCESS)
 134                 efi_printk(sys_table_arg, "Failed to get initrd info\n");
 135
 136         return status;
 137 }
 138
 139
 140
 141 void efi_char16_printk(efi_system_table_t *sys_table_arg,
 142                               efi_char16_t *str)
 143 {
 144         struct efi_simple_text_output_protocol *out;
 145
 146         out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
 147         out->output_string(out, str);
 148 }
 149
 150
 151 /*
 152  * This function handles the architcture specific differences between arm and
 153  * arm64 regarding where the kernel image must be loaded and any memory that
 154  * must be reserved. On failure it is required to free all
 155  * all allocations it has made.
 156  */
 157 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
 158                                  unsigned long *image_addr,
 159                                  unsigned long *image_size,
 160                                  unsigned long *reserve_addr,
 161                                  unsigned long *reserve_size,
 162                                  unsigned long dram_base,
 163                                  efi_loaded_image_t *image);
 164 /*
 165  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 166  * that is described in the PE/COFF header.  Most of the code is the same
 167  * for both archictectures, with the arch-specific code provided in the
 168  * handle_kernel_image() function.
 169  */
 170 unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 171                                unsigned long *image_addr)
 172 {
 173         efi_loaded_image_t *image;
 174         efi_status_t status;
 175         unsigned long image_size = 0;
 176         unsigned long dram_base;
 177         /* addr/point and size pairs for memory management*/
 178         unsigned long initrd_addr;
 179         u64 initrd_size = 0;
 180         unsigned long fdt_addr = 0;  /* Original DTB */
 181         unsigned long fdt_size = 0;
 182         char *cmdline_ptr = NULL;
 183         int cmdline_size = 0;
 184         unsigned long new_fdt_addr;
 185         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
 186         unsigned long reserve_addr = 0;
 187         unsigned long reserve_size = 0;
 188
 189         /* Check if we were booted by the EFI firmware */
 190         if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 191                 goto fail;
 192
 193         pr_efi(sys_table, "Booting Linux Kernel...\n");
 194
 195         /*
 196          * Get a handle to the loaded image protocol.  This is used to get
 197          * information about the running image, such as size and the command
 198          * line.
 199          */
 200         status = sys_table->boottime->handle_protocol(handle,
 201                                         &loaded_image_proto, (void *)&image);
 202         if (status != EFI_SUCCESS) {
 203                 pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
 204                 goto fail;
 205         }
 206
 207         dram_base = get_dram_base(sys_table);
 208         if (dram_base == EFI_ERROR) {
 209                 pr_efi_err(sys_table, "Failed to find DRAM base\n");
 210                 goto fail;
 211         }
 212
 213         /*
 214          * Get the command line from EFI, using the LOADED_IMAGE
 215          * protocol. We are going to copy the command line into the
 216          * device tree, so this can be allocated anywhere.
 217          */
 218         cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
 219         if (!cmdline_ptr) {
 220                 pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
 221                 goto fail;
 222         }
 223
 224         /* check whether 'nokaslr' was passed on the command line */
 225         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
 226                 static const u8 default_cmdline[] = CONFIG_CMDLINE;
 227                 const u8 *str, *cmdline = cmdline_ptr;
 228
 229                 if (IS_ENABLED(CONFIG_CMDLINE_FORCE))
 230                         cmdline = default_cmdline;
 231                 str = strstr(cmdline, "nokaslr");
 232                 if (str == cmdline || (str > cmdline && *(str - 1) == ' '))
 233                         __nokaslr = true;
 234         }
 235
 236         status = handle_kernel_image(sys_table, image_addr, &image_size,
 237                                      &reserve_addr,
 238                                      &reserve_size,
 239                                      dram_base, image);
 240         if (status != EFI_SUCCESS) {
 241                 pr_efi_err(sys_table, "Failed to relocate kernel\n");
 242                 goto fail_free_cmdline;
 243         }
 244
 245         status = efi_parse_options(cmdline_ptr);
 246         if (status != EFI_SUCCESS)
 247                 pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n");
 248
 249         /*
 250          * Unauthenticated device tree data is a security hazard, so
 251          * ignore 'dtb=' unless UEFI Secure Boot is disabled.
 252          */
 253         if (efi_secureboot_enabled(sys_table)) {
 254                 pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
 255         } else {
 256                 status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 257                                               "dtb=",
 258                                               ~0UL, &fdt_addr, &fdt_size);
 259
 260                 if (status != EFI_SUCCESS) {
 261                         pr_efi_err(sys_table, "Failed to load device tree!\n");
 262                         goto fail_free_image;
 263                 }
 264         }
 265
 266         if (fdt_addr) {
 267                 pr_efi(sys_table, "Using DTB from command line\n");
 268         } else {
 269                 /* Look for a device tree configuration table entry. */
 270                 fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
 271                 if (fdt_addr)
 272                         pr_efi(sys_table, "Using DTB from configuration table\n");
 273         }
 274
 275         if (!fdt_addr)
 276                 pr_efi(sys_table, "Generating empty DTB\n");
 277
 278         status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 279                                       "initrd=", dram_base + SZ_512M,
 280                                       (unsigned long *)&initrd_addr,
 281                                       (unsigned long *)&initrd_size);
 282         if (status != EFI_SUCCESS)
 283                 pr_efi_err(sys_table, "Failed initrd from command line!\n");
 284
 285         new_fdt_addr = fdt_addr;
 286         status = allocate_new_fdt_and_exit_boot(sys_table, handle,
 287                                 &new_fdt_addr, dram_base + MAX_FDT_OFFSET,
 288                                 initrd_addr, initrd_size, cmdline_ptr,
 289                                 fdt_addr, fdt_size);
 290
 291         /*
 292          * If all went well, we need to return the FDT address to the
 293          * calling function so it can be passed to kernel as part of
 294          * the kernel boot protocol.
 295          */
 296         if (status == EFI_SUCCESS)
 297                 return new_fdt_addr;
 298
 299         pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
 300
 301         efi_free(sys_table, initrd_size, initrd_addr);
 302         efi_free(sys_table, fdt_size, fdt_addr);
 303
 304 fail_free_image:
 305         efi_free(sys_table, image_size, *image_addr);
 306         efi_free(sys_table, reserve_size, reserve_addr);
 307 fail_free_cmdline:
 308         efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
 309 fail:
 310         return EFI_ERROR;
 311 }
 312
 313 /*
 314  * This is the base address at which to start allocating virtual memory ranges
 315  * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
 316  * any allocation we choose, and eliminate the risk of a conflict after kexec.
 317  * The value chosen is the largest non-zero power of 2 suitable for this purpose
 318  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
 319  * be mapped efficiently.
 320  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
 321  * map everything below 1 GB.
 322  */
 323 #define EFI_RT_VIRTUAL_BASE     SZ_512M
 324
 325 static int cmp_mem_desc(const void *l, const void *r)
 326 {
 327         const efi_memory_desc_t *left = l, *right = r;
 328
 329         return (left->phys_addr > right->phys_addr) ? 1 : -1;
 330 }
 331
 332 /*
 333  * Returns whether region @left ends exactly where region @right starts,
 334  * or false if either argument is NULL.
 335  */
 336 static bool regions_are_adjacent(efi_memory_desc_t *left,
 337                                  efi_memory_desc_t *right)
 338 {
 339         u64 left_end;
 340
 341         if (left == NULL || right == NULL)
 342                 return false;
 343
 344         left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
 345
 346         return left_end == right->phys_addr;
 347 }
 348
 349 /*
 350  * Returns whether region @left and region @right have compatible memory type
 351  * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 352  */
 353 static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
 354                                                       efi_memory_desc_t *right)
 355 {
 356         static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
 357                                          EFI_MEMORY_WC | EFI_MEMORY_UC |
 358                                          EFI_MEMORY_RUNTIME;
 359
 360         return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
 361 }
 362
 363 /*
 364  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 365  *
 366  * This function populates the virt_addr fields of all memory region descriptors
 367  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 368  * are also copied to @runtime_map, and their total count is returned in @count.
 369  */
 370 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 371                      unsigned long desc_size, efi_memory_desc_t *runtime_map,
 372                      int *count)
 373 {
 374         u64 efi_virt_base = EFI_RT_VIRTUAL_BASE;
 375         efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
 376         int l;
 377
 378         /*
 379          * To work around potential issues with the Properties Table feature
 380          * introduced in UEFI 2.5, which may split PE/COFF executable images
 381          * in memory into several RuntimeServicesCode and RuntimeServicesData
 382          * regions, we need to preserve the relative offsets between adjacent
 383          * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
 384          * The easiest way to find adjacent regions is to sort the memory map
 385          * before traversing it.
 386          */
 387         sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);
 388
 389         for (l = 0; l < map_size; l += desc_size, prev = in) {
 390                 u64 paddr, size;
 391
 392                 in = (void *)memory_map + l;
 393                 if (!(in->attribute & EFI_MEMORY_RUNTIME))
 394                         continue;
 395
 396                 paddr = in->phys_addr;
 397                 size = in->num_pages * EFI_PAGE_SIZE;
 398
 399                 /*
 400                  * Make the mapping compatible with 64k pages: this allows
 401                  * a 4k page size kernel to kexec a 64k page size kernel and
 402                  * vice versa.
 403                  */
 404                 if (!regions_are_adjacent(prev, in) ||
 405                     !regions_have_compatible_memory_type_attrs(prev, in)) {
 406
 407                         paddr = round_down(in->phys_addr, SZ_64K);
 408                         size += in->phys_addr - paddr;
 409
 410                         /*
 411                          * Avoid wasting memory on PTEs by choosing a virtual
 412                          * base that is compatible with section mappings if this
 413                          * region has the appropriate size and physical
 414                          * alignment. (Sections are 2 MB on 4k granule kernels)
 415                          */
 416                         if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 417                                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
 418                         else
 419                                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
 420                 }
 421
 422                 in->virt_addr = efi_virt_base + in->phys_addr - paddr;
 423                 efi_virt_base += size;
 424
 425                 memcpy(out, in, desc_size);
 426                 out = (void *)out + desc_size;
 427                 ++*count;
 428         }
 429 }