drivers/of/kexec.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2020 Arm Limited
   4  *
   5  * Based on arch/arm64/kernel/machine_kexec_file.c:
   6  *  Copyright (C) 2018 Linaro Limited
   7  *
   8  * And arch/powerpc/kexec/file_load.c:
   9  *  Copyright (C) 2016  IBM Corporation
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/kexec.h>
  14 #include <linux/memblock.h>
  15 #include <linux/libfdt.h>
  16 #include <linux/of.h>
  17 #include <linux/of_fdt.h>
  18 #include <linux/random.h>
  19 #include <linux/types.h>
  20
  21 #define RNG_SEED_SIZE           128
  22
  23 /*
  24  * Additional space needed for the FDT buffer so that we can add initrd,
  25  * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
  26  */
  27 #define FDT_EXTRA_SPACE 0x1000
  28
  29 /**
  30  * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
  31  *
  32  * @fdt:        Flattened device tree for the current kernel.
  33  * @start:      Starting address of the reserved memory.
  34  * @size:       Size of the reserved memory.
  35  *
  36  * Return: 0 on success, or negative errno on error.
  37  */
  38 static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
  39 {
  40         int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
  41
  42         for (i = 0; i < num_rsvs; i++) {
  43                 u64 rsv_start, rsv_size;
  44
  45                 ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
  46                 if (ret) {
  47                         pr_err("Malformed device tree.\n");
  48                         return -EINVAL;
  49                 }
  50
  51                 if (rsv_start == start && rsv_size == size) {
  52                         ret = fdt_del_mem_rsv(fdt, i);
  53                         if (ret) {
  54                                 pr_err("Error deleting device tree reservation.\n");
  55                                 return -EINVAL;
  56                         }
  57
  58                         return 0;
  59                 }
  60         }
  61
  62         return -ENOENT;
  63 }
  64
  65 /**
  66  * get_addr_size_cells - Get address and size of root node
  67  *
  68  * @addr_cells: Return address of the root node
  69  * @size_cells: Return size of the root node
  70  *
  71  * Return: 0 on success, or negative errno on error.
  72  */
  73 static int get_addr_size_cells(int *addr_cells, int *size_cells)
  74 {
  75         struct device_node *root;
  76
  77         root = of_find_node_by_path("/");
  78         if (!root)
  79                 return -EINVAL;
  80
  81         *addr_cells = of_n_addr_cells(root);
  82         *size_cells = of_n_size_cells(root);
  83
  84         of_node_put(root);
  85
  86         return 0;
  87 }
  88
  89 /**
  90  * do_get_kexec_buffer - Get address and size of device tree property
  91  *
  92  * @prop: Device tree property
  93  * @len: Size of @prop
  94  * @addr: Return address of the node
  95  * @size: Return size of the node
  96  *
  97  * Return: 0 on success, or negative errno on error.
  98  */
  99 static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
 100                                size_t *size)
 101 {
 102         int ret, addr_cells, size_cells;
 103
 104         ret = get_addr_size_cells(&addr_cells, &size_cells);
 105         if (ret)
 106                 return ret;
 107
 108         if (len < 4 * (addr_cells + size_cells))
 109                 return -ENOENT;
 110
 111         *addr = of_read_number(prop, addr_cells);
 112         *size = of_read_number(prop + 4 * addr_cells, size_cells);
 113
 114         return 0;
 115 }
 116
 117 /**
 118  * ima_get_kexec_buffer - get IMA buffer from the previous kernel
 119  * @addr:       On successful return, set to point to the buffer contents.
 120  * @size:       On successful return, set to the buffer size.
 121  *
 122  * Return: 0 on success, negative errno on error.
 123  */
 124 int ima_get_kexec_buffer(void **addr, size_t *size)
 125 {
 126         int ret, len;
 127         unsigned long tmp_addr;
 128         size_t tmp_size;
 129         const void *prop;
 130
 131         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 132                 return -ENOTSUPP;
 133
 134         prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
 135         if (!prop)
 136                 return -ENOENT;
 137
 138         ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
 139         if (ret)
 140                 return ret;
 141
 142         *addr = __va(tmp_addr);
 143         *size = tmp_size;
 144
 145         return 0;
 146 }
 147
 148 /**
 149  * ima_free_kexec_buffer - free memory used by the IMA buffer
 150  */
 151 int ima_free_kexec_buffer(void)
 152 {
 153         int ret;
 154         unsigned long addr;
 155         size_t size;
 156         struct property *prop;
 157
 158         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 159                 return -ENOTSUPP;
 160
 161         prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
 162         if (!prop)
 163                 return -ENOENT;
 164
 165         ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
 166         if (ret)
 167                 return ret;
 168
 169         ret = of_remove_property(of_chosen, prop);
 170         if (ret)
 171                 return ret;
 172
 173         return memblock_free(addr, size);
 174
 175 }
 176
 177 /**
 178  * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
 179  *
 180  * @fdt: Flattened Device Tree to update
 181  * @chosen_node: Offset to the chosen node in the device tree
 182  *
 183  * The IMA measurement buffer is of no use to a subsequent kernel, so we always
 184  * remove it from the device tree.
 185  */
 186 static void remove_ima_buffer(void *fdt, int chosen_node)
 187 {
 188         int ret, len;
 189         unsigned long addr;
 190         size_t size;
 191         const void *prop;
 192
 193         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 194                 return;
 195
 196         prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
 197         if (!prop)
 198                 return;
 199
 200         ret = do_get_kexec_buffer(prop, len, &addr, &size);
 201         fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
 202         if (ret)
 203                 return;
 204
 205         ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
 206         if (!ret)
 207                 pr_debug("Removed old IMA buffer reservation.\n");
 208 }
 209
 210 #ifdef CONFIG_IMA_KEXEC
 211 /**
 212  * setup_ima_buffer - add IMA buffer information to the fdt
 213  * @image:              kexec image being loaded.
 214  * @fdt:                Flattened device tree for the next kernel.
 215  * @chosen_node:        Offset to the chosen node.
 216  *
 217  * Return: 0 on success, or negative errno on error.
 218  */
 219 static int setup_ima_buffer(const struct kimage *image, void *fdt,
 220                             int chosen_node)
 221 {
 222         int ret;
 223
 224         if (!image->ima_buffer_size)
 225                 return 0;
 226
 227         ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 228                                        "linux,ima-kexec-buffer",
 229                                        image->ima_buffer_addr,
 230                                        image->ima_buffer_size);
 231         if (ret < 0)
 232                 return -EINVAL;
 233
 234         ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
 235                               image->ima_buffer_size);
 236         if (ret)
 237                 return -EINVAL;
 238
 239         pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
 240                  image->ima_buffer_addr, image->ima_buffer_size);
 241
 242         return 0;
 243 }
 244 #else /* CONFIG_IMA_KEXEC */
 245 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
 246                                    int chosen_node)
 247 {
 248         return 0;
 249 }
 250 #endif /* CONFIG_IMA_KEXEC */
 251
 252 /*
 253  * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
 254  *
 255  * @image:              kexec image being loaded.
 256  * @initrd_load_addr:   Address where the next initrd will be loaded.
 257  * @initrd_len:         Size of the next initrd, or 0 if there will be none.
 258  * @cmdline:            Command line for the next kernel, or NULL if there will
 259  *                      be none.
 260  * @extra_fdt_size:     Additional size for the new FDT buffer.
 261  *
 262  * Return: fdt on success, or NULL errno on error.
 263  */
 264 void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 265                                    unsigned long initrd_load_addr,
 266                                    unsigned long initrd_len,
 267                                    const char *cmdline, size_t extra_fdt_size)
 268 {
 269         void *fdt;
 270         int ret, chosen_node;
 271         const void *prop;
 272         size_t fdt_size;
 273
 274         fdt_size = fdt_totalsize(initial_boot_params) +
 275                    (cmdline ? strlen(cmdline) : 0) +
 276                    FDT_EXTRA_SPACE +
 277                    extra_fdt_size;
 278         fdt = kvmalloc(fdt_size, GFP_KERNEL);
 279         if (!fdt)
 280                 return NULL;
 281
 282         ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
 283         if (ret < 0) {
 284                 pr_err("Error %d setting up the new device tree.\n", ret);
 285                 goto out;
 286         }
 287
 288         /* Remove memory reservation for the current device tree. */
 289         ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
 290                                        fdt_totalsize(initial_boot_params));
 291         if (ret == -EINVAL) {
 292                 pr_err("Error removing memory reservation.\n");
 293                 goto out;
 294         }
 295
 296         chosen_node = fdt_path_offset(fdt, "/chosen");
 297         if (chosen_node == -FDT_ERR_NOTFOUND)
 298                 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
 299                                               "chosen");
 300         if (chosen_node < 0) {
 301                 ret = chosen_node;
 302                 goto out;
 303         }
 304
 305         ret = fdt_delprop(fdt, chosen_node, "linux,elfcorehdr");
 306         if (ret && ret != -FDT_ERR_NOTFOUND)
 307                 goto out;
 308         ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range");
 309         if (ret && ret != -FDT_ERR_NOTFOUND)
 310                 goto out;
 311
 312         /* Did we boot using an initrd? */
 313         prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
 314         if (prop) {
 315                 u64 tmp_start, tmp_end, tmp_size;
 316
 317                 tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
 318
 319                 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
 320                 if (!prop) {
 321                         ret = -EINVAL;
 322                         goto out;
 323                 }
 324
 325                 tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
 326
 327                 /*
 328                  * kexec reserves exact initrd size, while firmware may
 329                  * reserve a multiple of PAGE_SIZE, so check for both.
 330                  */
 331                 tmp_size = tmp_end - tmp_start;
 332                 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
 333                 if (ret == -ENOENT)
 334                         ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
 335                                                        round_up(tmp_size, PAGE_SIZE));
 336                 if (ret == -EINVAL)
 337                         goto out;
 338         }
 339
 340         /* add initrd-* */
 341         if (initrd_load_addr) {
 342                 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
 343                                       initrd_load_addr);
 344                 if (ret)
 345                         goto out;
 346
 347                 ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
 348                                       initrd_load_addr + initrd_len);
 349                 if (ret)
 350                         goto out;
 351
 352                 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
 353                 if (ret)
 354                         goto out;
 355
 356         } else {
 357                 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
 358                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 359                         goto out;
 360
 361                 ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
 362                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 363                         goto out;
 364         }
 365
 366         if (image->type == KEXEC_TYPE_CRASH) {
 367                 /* add linux,elfcorehdr */
 368                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 369                                 "linux,elfcorehdr", image->elf_load_addr,
 370                                 image->elf_headers_sz);
 371                 if (ret)
 372                         goto out;
 373
 374                 /*
 375                  * Avoid elfcorehdr from being stomped on in kdump kernel by
 376                  * setting up memory reserve map.
 377                  */
 378                 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
 379                                       image->elf_headers_sz);
 380                 if (ret)
 381                         goto out;
 382
 383                 /* add linux,usable-memory-range */
 384                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 385                                 "linux,usable-memory-range", crashk_res.start,
 386                                 crashk_res.end - crashk_res.start + 1);
 387                 if (ret)
 388                         goto out;
 389         }
 390
 391         /* add bootargs */
 392         if (cmdline) {
 393                 ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
 394                 if (ret)
 395                         goto out;
 396         } else {
 397                 ret = fdt_delprop(fdt, chosen_node, "bootargs");
 398                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 399                         goto out;
 400         }
 401
 402         /* add kaslr-seed */
 403         ret = fdt_delprop(fdt, chosen_node, "kaslr-seed");
 404         if (ret == -FDT_ERR_NOTFOUND)
 405                 ret = 0;
 406         else if (ret)
 407                 goto out;
 408
 409         if (rng_is_initialized()) {
 410                 u64 seed = get_random_u64();
 411
 412                 ret = fdt_setprop_u64(fdt, chosen_node, "kaslr-seed", seed);
 413                 if (ret)
 414                         goto out;
 415         } else {
 416                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 417                           "kaslr-seed");
 418         }
 419
 420         /* add rng-seed */
 421         if (rng_is_initialized()) {
 422                 void *rng_seed;
 423
 424                 ret = fdt_setprop_placeholder(fdt, chosen_node, "rng-seed",
 425                                 RNG_SEED_SIZE, &rng_seed);
 426                 if (ret)
 427                         goto out;
 428                 get_random_bytes(rng_seed, RNG_SEED_SIZE);
 429         } else {
 430                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 431                           "rng-seed");
 432         }
 433
 434         ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
 435         if (ret)
 436                 goto out;
 437
 438         remove_ima_buffer(fdt, chosen_node);
 439         ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
 440
 441 out:
 442         if (ret) {
 443                 kvfree(fdt);
 444                 fdt = NULL;
 445         }
 446
 447         return fdt;
 448 }