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 /*
  22  * This is the base address at which to start allocating virtual memory ranges
  23  * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
  24  * any allocation we choose, and eliminate the risk of a conflict after kexec.
  25  * The value chosen is the largest non-zero power of 2 suitable for this purpose
  26  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
  27  * be mapped efficiently.
  28  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
  29  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
  30  * entire footprint of the UEFI runtime services memory regions)
  31  */
  32 #define EFI_RT_VIRTUAL_BASE     SZ_512M
  33 #define EFI_RT_VIRTUAL_SIZE     SZ_512M
  34
  35 #ifdef CONFIG_ARM64
  36 # define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE_64
  37 #else
  38 # define EFI_RT_VIRTUAL_LIMIT   TASK_SIZE
  39 #endif
  40
  41 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
  42
  43 efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
  44                              void *__image, void **__fh)
  45 {
  46         efi_file_io_interface_t *io;
  47         efi_loaded_image_t *image = __image;
  48         efi_file_handle_t *fh;
  49         efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
  50         efi_status_t status;
  51         void *handle = (void *)(unsigned long)image->device_handle;
  52
  53         status = sys_table_arg->boottime->handle_protocol(handle,
  54                                  &fs_proto, (void **)&io);
  55         if (status != EFI_SUCCESS) {
  56                 efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
  57                 return status;
  58         }
  59
  60         status = io->open_volume(io, &fh);
  61         if (status != EFI_SUCCESS)
  62                 efi_printk(sys_table_arg, "Failed to open volume\n");
  63
  64         *__fh = fh;
  65         return status;
  66 }
  67
  68 void efi_char16_printk(efi_system_table_t *sys_table_arg,
  69                               efi_char16_t *str)
  70 {
  71         struct efi_simple_text_output_protocol *out;
  72
  73         out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
  74         out->output_string(out, str);
  75 }
  76
  77 static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
  78 {
  79         efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
  80         efi_status_t status;
  81         unsigned long size;
  82         void **gop_handle = NULL;
  83         struct screen_info *si = NULL;
  84
  85         size = 0;
  86         status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
  87                                 &gop_proto, NULL, &size, gop_handle);
  88         if (status == EFI_BUFFER_TOO_SMALL) {
  89                 si = alloc_screen_info(sys_table_arg);
  90                 if (!si)
  91                         return NULL;
  92                 efi_setup_gop(sys_table_arg, si, &gop_proto, size);
  93         }
  94         return si;
  95 }
  96
  97 /*
  98  * This function handles the architcture specific differences between arm and
  99  * arm64 regarding where the kernel image must be loaded and any memory that
 100  * must be reserved. On failure it is required to free all
 101  * all allocations it has made.
 102  */
 103 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
 104                                  unsigned long *image_addr,
 105                                  unsigned long *image_size,
 106                                  unsigned long *reserve_addr,
 107                                  unsigned long *reserve_size,
 108                                  unsigned long dram_base,
 109                                  efi_loaded_image_t *image);
 110 /*
 111  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 112  * that is described in the PE/COFF header.  Most of the code is the same
 113  * for both archictectures, with the arch-specific code provided in the
 114  * handle_kernel_image() function.
 115  */
 116 unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 117                                unsigned long *image_addr)
 118 {
 119         efi_loaded_image_t *image;
 120         efi_status_t status;
 121         unsigned long image_size = 0;
 122         unsigned long dram_base;
 123         /* addr/point and size pairs for memory management*/
 124         unsigned long initrd_addr;
 125         u64 initrd_size = 0;
 126         unsigned long fdt_addr = 0;  /* Original DTB */
 127         unsigned long fdt_size = 0;
 128         char *cmdline_ptr = NULL;
 129         int cmdline_size = 0;
 130         unsigned long new_fdt_addr;
 131         efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
 132         unsigned long reserve_addr = 0;
 133         unsigned long reserve_size = 0;
 134         enum efi_secureboot_mode secure_boot;
 135         struct screen_info *si;
 136
 137         /* Check if we were booted by the EFI firmware */
 138         if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 139                 goto fail;
 140
 141         status = check_platform_features(sys_table);
 142         if (status != EFI_SUCCESS)
 143                 goto fail;
 144
 145         /*
 146          * Get a handle to the loaded image protocol.  This is used to get
 147          * information about the running image, such as size and the command
 148          * line.
 149          */
 150         status = sys_table->boottime->handle_protocol(handle,
 151                                         &loaded_image_proto, (void *)&image);
 152         if (status != EFI_SUCCESS) {
 153                 pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
 154                 goto fail;
 155         }
 156
 157         dram_base = get_dram_base(sys_table);
 158         if (dram_base == EFI_ERROR) {
 159                 pr_efi_err(sys_table, "Failed to find DRAM base\n");
 160                 goto fail;
 161         }
 162
 163         /*
 164          * Get the command line from EFI, using the LOADED_IMAGE
 165          * protocol. We are going to copy the command line into the
 166          * device tree, so this can be allocated anywhere.
 167          */
 168         cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
 169         if (!cmdline_ptr) {
 170                 pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
 171                 goto fail;
 172         }
 173
 174         if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
 175             IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
 176             cmdline_size == 0)
 177                 efi_parse_options(CONFIG_CMDLINE);
 178
 179         if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
 180                 efi_parse_options(cmdline_ptr);
 181
 182         pr_efi(sys_table, "Booting Linux Kernel...\n");
 183
 184         si = setup_graphics(sys_table);
 185
 186         status = handle_kernel_image(sys_table, image_addr, &image_size,
 187                                      &reserve_addr,
 188                                      &reserve_size,
 189                                      dram_base, image);
 190         if (status != EFI_SUCCESS) {
 191                 pr_efi_err(sys_table, "Failed to relocate kernel\n");
 192                 goto fail_free_cmdline;
 193         }
 194
 195         /* Ask the firmware to clear memory on unclean shutdown */
 196         efi_enable_reset_attack_mitigation(sys_table);
 197
 198         secure_boot = efi_get_secureboot(sys_table);
 199
 200         /*
 201          * Unauthenticated device tree data is a security hazard, so ignore
 202          * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
 203          * boot is enabled if we can't determine its state.
 204          */
 205         if (secure_boot != efi_secureboot_mode_disabled &&
 206             strstr(cmdline_ptr, "dtb=")) {
 207                 pr_efi(sys_table, "Ignoring DTB from command line.\n");
 208         } else {
 209                 status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 210                                               "dtb=",
 211                                               ~0UL, &fdt_addr, &fdt_size);
 212
 213                 if (status != EFI_SUCCESS) {
 214                         pr_efi_err(sys_table, "Failed to load device tree!\n");
 215                         goto fail_free_image;
 216                 }
 217         }
 218
 219         if (fdt_addr) {
 220                 pr_efi(sys_table, "Using DTB from command line\n");
 221         } else {
 222                 /* Look for a device tree configuration table entry. */
 223                 fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
 224                 if (fdt_addr)
 225                         pr_efi(sys_table, "Using DTB from configuration table\n");
 226         }
 227
 228         if (!fdt_addr)
 229                 pr_efi(sys_table, "Generating empty DTB\n");
 230
 231         status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
 232                                       efi_get_max_initrd_addr(dram_base,
 233                                                               *image_addr),
 234                                       (unsigned long *)&initrd_addr,
 235                                       (unsigned long *)&initrd_size);
 236         if (status != EFI_SUCCESS)
 237                 pr_efi_err(sys_table, "Failed initrd from command line!\n");
 238
 239         efi_random_get_seed(sys_table);
 240
 241         if (!nokaslr()) {
 242                 /*
 243                  * Randomize the base of the UEFI runtime services region.
 244                  * Preserve the 2 MB alignment of the region by taking a
 245                  * shift of 21 bit positions into account when scaling
 246                  * the headroom value using a 32-bit random value.
 247                  */
 248                 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
 249                                             EFI_RT_VIRTUAL_BASE -
 250                                             EFI_RT_VIRTUAL_SIZE;
 251                 u32 rnd;
 252
 253                 status = efi_get_random_bytes(sys_table, sizeof(rnd),
 254                                               (u8 *)&rnd);
 255                 if (status == EFI_SUCCESS) {
 256                         virtmap_base = EFI_RT_VIRTUAL_BASE +
 257                                        (((headroom >> 21) * rnd) >> (32 - 21));
 258                 }
 259         }
 260
 261         new_fdt_addr = fdt_addr;
 262         status = allocate_new_fdt_and_exit_boot(sys_table, handle,
 263                                 &new_fdt_addr, efi_get_max_fdt_addr(dram_base),
 264                                 initrd_addr, initrd_size, cmdline_ptr,
 265                                 fdt_addr, fdt_size);
 266
 267         /*
 268          * If all went well, we need to return the FDT address to the
 269          * calling function so it can be passed to kernel as part of
 270          * the kernel boot protocol.
 271          */
 272         if (status == EFI_SUCCESS)
 273                 return new_fdt_addr;
 274
 275         pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
 276
 277         efi_free(sys_table, initrd_size, initrd_addr);
 278         efi_free(sys_table, fdt_size, fdt_addr);
 279
 280 fail_free_image:
 281         efi_free(sys_table, image_size, *image_addr);
 282         efi_free(sys_table, reserve_size, reserve_addr);
 283 fail_free_cmdline:
 284         free_screen_info(sys_table, si);
 285         efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
 286 fail:
 287         return EFI_ERROR;
 288 }
 289
 290 static int cmp_mem_desc(const void *l, const void *r)
 291 {
 292         const efi_memory_desc_t *left = l, *right = r;
 293
 294         return (left->phys_addr > right->phys_addr) ? 1 : -1;
 295 }
 296
 297 /*
 298  * Returns whether region @left ends exactly where region @right starts,
 299  * or false if either argument is NULL.
 300  */
 301 static bool regions_are_adjacent(efi_memory_desc_t *left,
 302                                  efi_memory_desc_t *right)
 303 {
 304         u64 left_end;
 305
 306         if (left == NULL || right == NULL)
 307                 return false;
 308
 309         left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
 310
 311         return left_end == right->phys_addr;
 312 }
 313
 314 /*
 315  * Returns whether region @left and region @right have compatible memory type
 316  * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 317  */
 318 static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
 319                                                       efi_memory_desc_t *right)
 320 {
 321         static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
 322                                          EFI_MEMORY_WC | EFI_MEMORY_UC |
 323                                          EFI_MEMORY_RUNTIME;
 324
 325         return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
 326 }
 327
 328 /*
 329  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 330  *
 331  * This function populates the virt_addr fields of all memory region descriptors
 332  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 333  * are also copied to @runtime_map, and their total count is returned in @count.
 334  */
 335 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 336                      unsigned long desc_size, efi_memory_desc_t *runtime_map,
 337                      int *count)
 338 {
 339         u64 efi_virt_base = virtmap_base;
 340         efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
 341         int l;
 342
 343         /*
 344          * To work around potential issues with the Properties Table feature
 345          * introduced in UEFI 2.5, which may split PE/COFF executable images
 346          * in memory into several RuntimeServicesCode and RuntimeServicesData
 347          * regions, we need to preserve the relative offsets between adjacent
 348          * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
 349          * The easiest way to find adjacent regions is to sort the memory map
 350          * before traversing it.
 351          */
 352         sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);
 353
 354         for (l = 0; l < map_size; l += desc_size, prev = in) {
 355                 u64 paddr, size;
 356
 357                 in = (void *)memory_map + l;
 358                 if (!(in->attribute & EFI_MEMORY_RUNTIME))
 359                         continue;
 360
 361                 paddr = in->phys_addr;
 362                 size = in->num_pages * EFI_PAGE_SIZE;
 363
 364                 /*
 365                  * Make the mapping compatible with 64k pages: this allows
 366                  * a 4k page size kernel to kexec a 64k page size kernel and
 367                  * vice versa.
 368                  */
 369                 if (!regions_are_adjacent(prev, in) ||
 370                     !regions_have_compatible_memory_type_attrs(prev, in)) {
 371
 372                         paddr = round_down(in->phys_addr, SZ_64K);
 373                         size += in->phys_addr - paddr;
 374
 375                         /*
 376                          * Avoid wasting memory on PTEs by choosing a virtual
 377                          * base that is compatible with section mappings if this
 378                          * region has the appropriate size and physical
 379                          * alignment. (Sections are 2 MB on 4k granule kernels)
 380                          */
 381                         if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 382                                 efi_virt_base = round_up(efi_virt_base, SZ_2M);
 383                         else
 384                                 efi_virt_base = round_up(efi_virt_base, SZ_64K);
 385                 }
 386
 387                 in->virt_addr = efi_virt_base + in->phys_addr - paddr;
 388                 efi_virt_base += size;
 389
 390                 memcpy(out, in, desc_size);
 391                 out = (void *)out + desc_size;
 392                 ++*count;
 393         }
 394 }