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