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 /* relevant device tree properties */
  22 #define FDT_PROP_KEXEC_ELFHDR   "linux,elfcorehdr"
  23 #define FDT_PROP_MEM_RANGE      "linux,usable-memory-range"
  24 #define FDT_PROP_INITRD_START   "linux,initrd-start"
  25 #define FDT_PROP_INITRD_END     "linux,initrd-end"
  26 #define FDT_PROP_BOOTARGS       "bootargs"
  27 #define FDT_PROP_KASLR_SEED     "kaslr-seed"
  28 #define FDT_PROP_RNG_SEED       "rng-seed"
  29 #define RNG_SEED_SIZE           128
  30
  31 /*
  32  * Additional space needed for the FDT buffer so that we can add initrd,
  33  * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
  34  */
  35 #define FDT_EXTRA_SPACE 0x1000
  36
  37 /**
  38  * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
  39  *
  40  * @fdt:        Flattened device tree for the current kernel.
  41  * @start:      Starting address of the reserved memory.
  42  * @size:       Size of the reserved memory.
  43  *
  44  * Return: 0 on success, or negative errno on error.
  45  */
  46 static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
  47 {
  48         int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
  49
  50         for (i = 0; i < num_rsvs; i++) {
  51                 u64 rsv_start, rsv_size;
  52
  53                 ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
  54                 if (ret) {
  55                         pr_err("Malformed device tree.\n");
  56                         return -EINVAL;
  57                 }
  58
  59                 if (rsv_start == start && rsv_size == size) {
  60                         ret = fdt_del_mem_rsv(fdt, i);
  61                         if (ret) {
  62                                 pr_err("Error deleting device tree reservation.\n");
  63                                 return -EINVAL;
  64                         }
  65
  66                         return 0;
  67                 }
  68         }
  69
  70         return -ENOENT;
  71 }
  72
  73 /**
  74  * get_addr_size_cells - Get address and size of root node
  75  *
  76  * @addr_cells: Return address of the root node
  77  * @size_cells: Return size of the root node
  78  *
  79  * Return: 0 on success, or negative errno on error.
  80  */
  81 static int get_addr_size_cells(int *addr_cells, int *size_cells)
  82 {
  83         struct device_node *root;
  84
  85         root = of_find_node_by_path("/");
  86         if (!root)
  87                 return -EINVAL;
  88
  89         *addr_cells = of_n_addr_cells(root);
  90         *size_cells = of_n_size_cells(root);
  91
  92         of_node_put(root);
  93
  94         return 0;
  95 }
  96
  97 /**
  98  * do_get_kexec_buffer - Get address and size of device tree property
  99  *
 100  * @prop: Device tree property
 101  * @len: Size of @prop
 102  * @addr: Return address of the node
 103  * @size: Return size of the node
 104  *
 105  * Return: 0 on success, or negative errno on error.
 106  */
 107 static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
 108                                size_t *size)
 109 {
 110         int ret, addr_cells, size_cells;
 111
 112         ret = get_addr_size_cells(&addr_cells, &size_cells);
 113         if (ret)
 114                 return ret;
 115
 116         if (len < 4 * (addr_cells + size_cells))
 117                 return -ENOENT;
 118
 119         *addr = of_read_number(prop, addr_cells);
 120         *size = of_read_number(prop + 4 * addr_cells, size_cells);
 121
 122         return 0;
 123 }
 124
 125 /**
 126  * ima_get_kexec_buffer - get IMA buffer from the previous kernel
 127  * @addr:       On successful return, set to point to the buffer contents.
 128  * @size:       On successful return, set to the buffer size.
 129  *
 130  * Return: 0 on success, negative errno on error.
 131  */
 132 int ima_get_kexec_buffer(void **addr, size_t *size)
 133 {
 134         int ret, len;
 135         unsigned long tmp_addr;
 136         size_t tmp_size;
 137         const void *prop;
 138
 139         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 140                 return -ENOTSUPP;
 141
 142         prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
 143         if (!prop)
 144                 return -ENOENT;
 145
 146         ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
 147         if (ret)
 148                 return ret;
 149
 150         *addr = __va(tmp_addr);
 151         *size = tmp_size;
 152
 153         return 0;
 154 }
 155
 156 /**
 157  * ima_free_kexec_buffer - free memory used by the IMA buffer
 158  */
 159 int ima_free_kexec_buffer(void)
 160 {
 161         int ret;
 162         unsigned long addr;
 163         size_t size;
 164         struct property *prop;
 165
 166         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 167                 return -ENOTSUPP;
 168
 169         prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
 170         if (!prop)
 171                 return -ENOENT;
 172
 173         ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
 174         if (ret)
 175                 return ret;
 176
 177         ret = of_remove_property(of_chosen, prop);
 178         if (ret)
 179                 return ret;
 180
 181         return memblock_free(addr, size);
 182
 183 }
 184
 185 /**
 186  * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
 187  *
 188  * @fdt: Flattened Device Tree to update
 189  * @chosen_node: Offset to the chosen node in the device tree
 190  *
 191  * The IMA measurement buffer is of no use to a subsequent kernel, so we always
 192  * remove it from the device tree.
 193  */
 194 static void remove_ima_buffer(void *fdt, int chosen_node)
 195 {
 196         int ret, len;
 197         unsigned long addr;
 198         size_t size;
 199         const void *prop;
 200
 201         if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
 202                 return;
 203
 204         prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
 205         if (!prop)
 206                 return;
 207
 208         ret = do_get_kexec_buffer(prop, len, &addr, &size);
 209         fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
 210         if (ret)
 211                 return;
 212
 213         ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
 214         if (!ret)
 215                 pr_debug("Removed old IMA buffer reservation.\n");
 216 }
 217
 218 #ifdef CONFIG_IMA_KEXEC
 219 /**
 220  * setup_ima_buffer - add IMA buffer information to the fdt
 221  * @image:              kexec image being loaded.
 222  * @fdt:                Flattened device tree for the next kernel.
 223  * @chosen_node:        Offset to the chosen node.
 224  *
 225  * Return: 0 on success, or negative errno on error.
 226  */
 227 static int setup_ima_buffer(const struct kimage *image, void *fdt,
 228                             int chosen_node)
 229 {
 230         int ret;
 231
 232         if (!image->ima_buffer_size)
 233                 return 0;
 234
 235         ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 236                                        "linux,ima-kexec-buffer",
 237                                        image->ima_buffer_addr,
 238                                        image->ima_buffer_size);
 239         if (ret < 0)
 240                 return -EINVAL;
 241
 242         ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
 243                               image->ima_buffer_size);
 244         if (ret)
 245                 return -EINVAL;
 246
 247         pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
 248                  image->ima_buffer_addr, image->ima_buffer_size);
 249
 250         return 0;
 251 }
 252 #else /* CONFIG_IMA_KEXEC */
 253 static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
 254                                    int chosen_node)
 255 {
 256         return 0;
 257 }
 258 #endif /* CONFIG_IMA_KEXEC */
 259
 260 /*
 261  * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
 262  *
 263  * @image:              kexec image being loaded.
 264  * @initrd_load_addr:   Address where the next initrd will be loaded.
 265  * @initrd_len:         Size of the next initrd, or 0 if there will be none.
 266  * @cmdline:            Command line for the next kernel, or NULL if there will
 267  *                      be none.
 268  * @extra_fdt_size:     Additional size for the new FDT buffer.
 269  *
 270  * Return: fdt on success, or NULL errno on error.
 271  */
 272 void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
 273                                    unsigned long initrd_load_addr,
 274                                    unsigned long initrd_len,
 275                                    const char *cmdline, size_t extra_fdt_size)
 276 {
 277         void *fdt;
 278         int ret, chosen_node;
 279         const void *prop;
 280         size_t fdt_size;
 281
 282         fdt_size = fdt_totalsize(initial_boot_params) +
 283                    (cmdline ? strlen(cmdline) : 0) +
 284                    FDT_EXTRA_SPACE +
 285                    extra_fdt_size;
 286         fdt = kvmalloc(fdt_size, GFP_KERNEL);
 287         if (!fdt)
 288                 return NULL;
 289
 290         ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
 291         if (ret < 0) {
 292                 pr_err("Error %d setting up the new device tree.\n", ret);
 293                 goto out;
 294         }
 295
 296         /* Remove memory reservation for the current device tree. */
 297         ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
 298                                        fdt_totalsize(initial_boot_params));
 299         if (ret == -EINVAL) {
 300                 pr_err("Error removing memory reservation.\n");
 301                 goto out;
 302         }
 303
 304         chosen_node = fdt_path_offset(fdt, "/chosen");
 305         if (chosen_node == -FDT_ERR_NOTFOUND)
 306                 chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
 307                                               "chosen");
 308         if (chosen_node < 0) {
 309                 ret = chosen_node;
 310                 goto out;
 311         }
 312
 313         ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_ELFHDR);
 314         if (ret && ret != -FDT_ERR_NOTFOUND)
 315                 goto out;
 316         ret = fdt_delprop(fdt, chosen_node, FDT_PROP_MEM_RANGE);
 317         if (ret && ret != -FDT_ERR_NOTFOUND)
 318                 goto out;
 319
 320         /* Did we boot using an initrd? */
 321         prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
 322         if (prop) {
 323                 u64 tmp_start, tmp_end, tmp_size;
 324
 325                 tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
 326
 327                 prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
 328                 if (!prop) {
 329                         ret = -EINVAL;
 330                         goto out;
 331                 }
 332
 333                 tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
 334
 335                 /*
 336                  * kexec reserves exact initrd size, while firmware may
 337                  * reserve a multiple of PAGE_SIZE, so check for both.
 338                  */
 339                 tmp_size = tmp_end - tmp_start;
 340                 ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
 341                 if (ret == -ENOENT)
 342                         ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
 343                                                        round_up(tmp_size, PAGE_SIZE));
 344                 if (ret == -EINVAL)
 345                         goto out;
 346         }
 347
 348         /* add initrd-* */
 349         if (initrd_load_addr) {
 350                 ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_START,
 351                                       initrd_load_addr);
 352                 if (ret)
 353                         goto out;
 354
 355                 ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_END,
 356                                       initrd_load_addr + initrd_len);
 357                 if (ret)
 358                         goto out;
 359
 360                 ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
 361                 if (ret)
 362                         goto out;
 363
 364         } else {
 365                 ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_START);
 366                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 367                         goto out;
 368
 369                 ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_END);
 370                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 371                         goto out;
 372         }
 373
 374         if (image->type == KEXEC_TYPE_CRASH) {
 375                 /* add linux,elfcorehdr */
 376                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 377                                 FDT_PROP_KEXEC_ELFHDR,
 378                                 image->elf_load_addr,
 379                                 image->elf_headers_sz);
 380                 if (ret)
 381                         goto out;
 382
 383                 /*
 384                  * Avoid elfcorehdr from being stomped on in kdump kernel by
 385                  * setting up memory reserve map.
 386                  */
 387                 ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
 388                                       image->elf_headers_sz);
 389                 if (ret)
 390                         goto out;
 391
 392                 /* add linux,usable-memory-range */
 393                 ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
 394                                 FDT_PROP_MEM_RANGE,
 395                                 crashk_res.start,
 396                                 crashk_res.end - crashk_res.start + 1);
 397                 if (ret)
 398                         goto out;
 399         }
 400
 401         /* add bootargs */
 402         if (cmdline) {
 403                 ret = fdt_setprop_string(fdt, chosen_node, FDT_PROP_BOOTARGS, cmdline);
 404                 if (ret)
 405                         goto out;
 406         } else {
 407                 ret = fdt_delprop(fdt, chosen_node, FDT_PROP_BOOTARGS);
 408                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 409                         goto out;
 410         }
 411
 412         /* add kaslr-seed */
 413         ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KASLR_SEED);
 414         if (ret == -FDT_ERR_NOTFOUND)
 415                 ret = 0;
 416         else if (ret)
 417                 goto out;
 418
 419         if (rng_is_initialized()) {
 420                 u64 seed = get_random_u64();
 421
 422                 ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_KASLR_SEED, seed);
 423                 if (ret)
 424                         goto out;
 425         } else {
 426                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 427                                 FDT_PROP_KASLR_SEED);
 428         }
 429
 430         /* add rng-seed */
 431         if (rng_is_initialized()) {
 432                 void *rng_seed;
 433
 434                 ret = fdt_setprop_placeholder(fdt, chosen_node, FDT_PROP_RNG_SEED,
 435                                 RNG_SEED_SIZE, &rng_seed);
 436                 if (ret)
 437                         goto out;
 438                 get_random_bytes(rng_seed, RNG_SEED_SIZE);
 439         } else {
 440                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 441                                 FDT_PROP_RNG_SEED);
 442         }
 443
 444         ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
 445         if (ret)
 446                 goto out;
 447
 448         remove_ima_buffer(fdt, chosen_node);
 449         ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
 450
 451 out:
 452         if (ret) {
 453                 kvfree(fdt);
 454                 fdt = NULL;
 455         }
 456
 457         return fdt;
 458 }