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 static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
  22 {
  23         static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
  24         static efi_char16_t const var_name[] = {
  25                 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
  26
  27         efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
  28         unsigned long size = sizeof(u8);
  29         efi_status_t status;
  30         u8 val;
  31
  32         status = f_getvar((efi_char16_t *)var_name, (efi_guid_t *)&var_guid,
  33                           NULL, &size, &val);
  34
  35         switch (status) {
  36         case EFI_SUCCESS:
  37                 return val;
  38         case EFI_NOT_FOUND:
  39                 return 0;
  40         default:
  41                 return 1;
  42         }
  43 }
  44
  45 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
  46                              void *__image, void **__fh)
  47 {
  48         efi_file_io_interface_t *io;
  49         efi_loaded_image_t *image = __image;
  50         efi_file_handle_t *fh;
  51         efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
  52         efi_status_t status;
  53         void *handle = (void *)(unsigned long)image->device_handle;
  54
  55         status = sys_table_arg->boottime->handle_protocol(handle,
  56                                  &fs_proto, (void **)&io);
  57         if (status != EFI_SUCCESS) {
  58                 efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
  59                 return status;
  60         }
  61
  62         status = io->open_volume(io, &fh);
  63         if (status != EFI_SUCCESS)
  64                 efi_printk(sys_table_arg, "Failed to open volume\n");
  65
  66         *__fh = fh;
  67         return status;
  68 }
  69
  70 efi_status_t efi_file_close(void *handle)
  71 {
  72         efi_file_handle_t *fh = handle;
  73
  74         return fh->close(handle);
  75 }
  76
  77 efi_status_t
  78 efi_file_read(void *handle, unsigned long *size, void *addr)
  79 {
  80         efi_file_handle_t *fh = handle;
  81
  82         return fh->read(handle, size, addr);
  83 }
  84
  85
  86 efi_status_t
  87 efi_file_size(efi_system_table_t *sys_table_arg, void *__fh,
  88               efi_char16_t *filename_16, void **handle, u64 *file_sz)
  89 {
  90         efi_file_handle_t *h, *fh = __fh;
  91         efi_file_info_t *info;
  92         efi_status_t status;
  93         efi_guid_t info_guid = EFI_FILE_INFO_ID;
  94         unsigned long info_sz;
  95
  96         status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, (u64)0);
  97         if (status != EFI_SUCCESS) {
  98                 efi_printk(sys_table_arg, "Failed to open file: ");
  99                 efi_char16_printk(sys_table_arg, filename_16);
 100                 efi_printk(sys_table_arg, "\n");
 101                 return status;
 102         }
 103
 104         *handle = h;
 105
 106         info_sz = 0;
 107         status = h->get_info(h, &info_guid, &info_sz, NULL);
 108         if (status != EFI_BUFFER_TOO_SMALL) {
 109                 efi_printk(sys_table_arg, "Failed to get file info size\n");
 110                 return status;
 111         }
 112
 113 grow:
 114         status = sys_table_arg->boottime->allocate_pool(EFI_LOADER_DATA,
 115                                  info_sz, (void **)&info);
 116         if (status != EFI_SUCCESS) {
 117                 efi_printk(sys_table_arg, "Failed to alloc mem for file info\n");
 118                 return status;
 119         }
 120
 121         status = h->get_info(h, &info_guid, &info_sz,
 122                                                    info);
 123         if (status == EFI_BUFFER_TOO_SMALL) {
 124                 sys_table_arg->boottime->free_pool(info);
 125                 goto grow;
 126         }
 127
 128         *file_sz = info->file_size;
 129         sys_table_arg->boottime->free_pool(info);
 130
 131         if (status != EFI_SUCCESS)
 132                 efi_printk(sys_table_arg, "Failed to get initrd info\n");
 133
 134         return status;
 135 }
 136
 137
 138
 139 void efi_char16_printk(efi_system_table_t *sys_table_arg,
 140                               efi_char16_t *str)
 141 {
 142         struct efi_simple_text_output_protocol *out;
 143
 144         out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
 145         out->output_string(out, str);
 146 }
 147
 148
 149 /*
 150  * This function handles the architcture specific differences between arm and
 151  * arm64 regarding where the kernel image must be loaded and any memory that
 152  * must be reserved. On failure it is required to free all
 153  * all allocations it has made.
 154  */
 155 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
 156                                  unsigned long *image_addr,
 157                                  unsigned long *image_size,
 158                                  unsigned long *reserve_addr,
 159                                  unsigned long *reserve_size,
 160                                  unsigned long dram_base,
 161                                  efi_loaded_image_t *image);
 162 /*
 163  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 164  * that is described in the PE/COFF header.  Most of the code is the same
 165  * for both archictectures, with the arch-specific code provided in the
 166  * handle_kernel_image() function.
 167  */
 168 unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 169                                unsigned long *image_addr)
 170 {
 171         efi_loaded_image_t *image;
 172         efi_status_t status;
 173         unsigned long image_size = 0;
 174         unsigned long dram_base;
 175         /* addr/point and size pairs for memory management*/
 176         unsigned long initrd_addr;
 177         u64 initrd_size = 0;
 178         unsigned long fdt_addr = 0;  /* Original DTB */
 179         unsigned long fdt_size = 0;
 180         char *cmdline_ptr = NULL;
 181         int cmdline_size = 0;
 182         unsigned long new_fdt_addr;
 183         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
 184         unsigned long reserve_addr = 0;
 185         unsigned long reserve_size = 0;
 186
 187         /* Check if we were booted by the EFI firmware */
 188         if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 189                 goto fail;
 190
 191         pr_efi(sys_table, "Booting Linux Kernel...\n");
 192
 193         /*
 194          * Get a handle to the loaded image protocol.  This is used to get
 195          * information about the running image, such as size and the command
 196          * line.
 197          */
 198         status = sys_table->boottime->handle_protocol(handle,
 199                                         &loaded_image_proto, (void *)&image);
 200         if (status != EFI_SUCCESS) {
 201                 pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
 202                 goto fail;
 203         }
 204
 205         dram_base = get_dram_base(sys_table);
 206         if (dram_base == EFI_ERROR) {
 207                 pr_efi_err(sys_table, "Failed to find DRAM base\n");
 208                 goto fail;
 209         }
 210         status = handle_kernel_image(sys_table, image_addr, &image_size,
 211                                      &reserve_addr,
 212                                      &reserve_size,
 213                                      dram_base, image);
 214         if (status != EFI_SUCCESS) {
 215                 pr_efi_err(sys_table, "Failed to relocate kernel\n");
 216                 goto fail;
 217         }
 218
 219         /*
 220          * Get the command line from EFI, using the LOADED_IMAGE
 221          * protocol. We are going to copy the command line into the
 222          * device tree, so this can be allocated anywhere.
 223          */
 224         cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
 225         if (!cmdline_ptr) {
 226                 pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
 227                 goto fail_free_image;
 228         }
 229
 230         status = efi_parse_options(cmdline_ptr);
 231         if (status != EFI_SUCCESS)
 232                 pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n");
 233
 234         /*
 235          * Unauthenticated device tree data is a security hazard, so
 236          * ignore 'dtb=' unless UEFI Secure Boot is disabled.
 237          */
 238         if (efi_secureboot_enabled(sys_table)) {
 239                 pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
 240         } else {
 241                 status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 242                                               "dtb=",
 243                                               ~0UL, &fdt_addr, &fdt_size);
 244
 245                 if (status != EFI_SUCCESS) {
 246                         pr_efi_err(sys_table, "Failed to load device tree!\n");
 247                         goto fail_free_cmdline;
 248                 }
 249         }
 250
 251         if (fdt_addr) {
 252                 pr_efi(sys_table, "Using DTB from command line\n");
 253         } else {
 254                 /* Look for a device tree configuration table entry. */
 255                 fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
 256                 if (fdt_addr)
 257                         pr_efi(sys_table, "Using DTB from configuration table\n");
 258         }
 259
 260         if (!fdt_addr)
 261                 pr_efi(sys_table, "Generating empty DTB\n");
 262
 263         status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 264                                       "initrd=", dram_base + SZ_512M,
 265                                       (unsigned long *)&initrd_addr,
 266                                       (unsigned long *)&initrd_size);
 267         if (status != EFI_SUCCESS)
 268                 pr_efi_err(sys_table, "Failed initrd from command line!\n");
 269
 270         new_fdt_addr = fdt_addr;
 271         status = allocate_new_fdt_and_exit_boot(sys_table, handle,
 272                                 &new_fdt_addr, dram_base + MAX_FDT_OFFSET,
 273                                 initrd_addr, initrd_size, cmdline_ptr,
 274                                 fdt_addr, fdt_size);
 275
 276         /*
 277          * If all went well, we need to return the FDT address to the
 278          * calling function so it can be passed to kernel as part of
 279          * the kernel boot protocol.
 280          */
 281         if (status == EFI_SUCCESS)
 282                 return new_fdt_addr;
 283
 284         pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
 285
 286         efi_free(sys_table, initrd_size, initrd_addr);
 287         efi_free(sys_table, fdt_size, fdt_addr);
 288
 289 fail_free_cmdline:
 290         efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
 291
 292 fail_free_image:
 293         efi_free(sys_table, image_size, *image_addr);
 294         efi_free(sys_table, reserve_size, reserve_addr);
 295 fail:
 296         return EFI_ERROR;
 297 }
 298
 299 /*
 300  * This is the base address at which to start allocating virtual memory ranges
 301  * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
 302  * any allocation we choose, and eliminate the risk of a conflict after kexec.
 303  * The value chosen is the largest non-zero power of 2 suitable for this purpose
 304  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
 305  * be mapped efficiently.
 306  */
 307 #define EFI_RT_VIRTUAL_BASE     0x40000000
 308
 309 static int cmp_mem_desc(const void *l, const void *r)
 310 {
 311         const efi_memory_desc_t *left = l, *right = r;
 312
 313         return (left->phys_addr > right->phys_addr) ? 1 : -1;
 314 }
 315
 316 /*
 317  * Returns whether region @left ends exactly where region @right starts,
 318  * or false if either argument is NULL.
 319  */
 320 static bool regions_are_adjacent(efi_memory_desc_t *left,
 321                                  efi_memory_desc_t *right)
 322 {
 323         u64 left_end;
 324
 325         if (left == NULL || right == NULL)
 326                 return false;
 327
 328         left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
 329
 330         return left_end == right->phys_addr;
 331 }
 332
 333 /*
 334  * Returns whether region @left and region @right have compatible memory type
 335  * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 336  */
 337 static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
 338                                                       efi_memory_desc_t *right)
 339 {
 340         static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
 341                                          EFI_MEMORY_WC | EFI_MEMORY_UC |
 342                                          EFI_MEMORY_RUNTIME;
 343
 344         return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
 345 }
 346
 347 /*
 348  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 349  *
 350  * This function populates the virt_addr fields of all memory region descriptors
 351  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 352  * are also copied to @runtime_map, and their total count is returned in @count.
 353  */
 354 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 355                      unsigned long desc_size, efi_memory_desc_t *runtime_map,
 356                      int *count)
 357 {
 358         u64 efi_virt_base = EFI_RT_VIRTUAL_BASE;
 359         efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
 360         int l;
 361
 362         /*
 363          * To work around potential issues with the Properties Table feature
 364          * introduced in UEFI 2.5, which may split PE/COFF executable images
 365          * in memory into several RuntimeServicesCode and RuntimeServicesData
 366          * regions, we need to preserve the relative offsets between adjacent
 367          * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
 368          * The easiest way to find adjacent regions is to sort the memory map
 369          * before traversing it.
 370          */
 371         sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);
 372
 373         for (l = 0; l < map_size; l += desc_size, prev = in) {
 374                 u64 paddr, size;
 375
 376                 in = (void *)memory_map + l;
 377                 if (!(in->attribute & EFI_MEMORY_RUNTIME))
 378                         continue;
 379
 380                 paddr = in->phys_addr;
 381                 size = in->num_pages * EFI_PAGE_SIZE;
 382
 383                 /*
 384                  * Make the mapping compatible with 64k pages: this allows
 385                  * a 4k page size kernel to kexec a 64k page size kernel and
 386                  * vice versa.
 387                  */
 388                 if (!regions_are_adjacent(prev, in) ||
 389                     !regions_have_compatible_memory_type_attrs(prev, in)) {
 390
 391                         paddr = round_down(in->phys_addr, SZ_64K);
 392                         size += in->phys_addr - paddr;
 393
 394                         /*
 395                          * Avoid wasting memory on PTEs by choosing a virtual
 396                          * base that is compatible with section mappings if this
 397                          * region has the appropriate size and physical
 398                          * alignment. (Sections are 2 MB on 4k granule kernels)
 399                          */
 400                         if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 401                                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
 402                         else
 403                                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
 404                 }
 405
 406                 in->virt_addr = efi_virt_base + in->phys_addr - paddr;
 407                 efi_virt_base += size;
 408
 409                 memcpy(out, in, desc_size);
 410                 out = (void *)out + desc_size;
 411                 ++*count;
 412         }
 413 }