arch/arm64/kernel/machine_kexec_file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kexec_file for arm64
   4  *
   5  * Copyright (C) 2018 Linaro Limited
   6  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
   7  *
   8  * Most code is derived from arm64 port of kexec-tools
   9  */
  10
  11 #define pr_fmt(fmt) "kexec_file: " fmt
  12
  13 #include <linux/ioport.h>
  14 #include <linux/kernel.h>
  15 #include <linux/kexec.h>
  16 #include <linux/libfdt.h>
  17 #include <linux/memblock.h>
  18 #include <linux/of_fdt.h>
  19 #include <linux/random.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.h>
  22 #include <linux/types.h>
  23 #include <linux/vmalloc.h>
  24 #include <asm/byteorder.h>
  25
  26 /* relevant device tree properties */
  27 #define FDT_PROP_KEXEC_ELFHDR   "linux,elfcorehdr"
  28 #define FDT_PROP_MEM_RANGE      "linux,usable-memory-range"
  29 #define FDT_PROP_INITRD_START   "linux,initrd-start"
  30 #define FDT_PROP_INITRD_END     "linux,initrd-end"
  31 #define FDT_PROP_BOOTARGS       "bootargs"
  32 #define FDT_PROP_KASLR_SEED     "kaslr-seed"
  33 #define FDT_PROP_RNG_SEED       "rng-seed"
  34 #define RNG_SEED_SIZE           128
  35
  36 const struct kexec_file_ops * const kexec_file_loaders[] = {
  37         &kexec_image_ops,
  38         NULL
  39 };
  40
  41 int arch_kimage_file_post_load_cleanup(struct kimage *image)
  42 {
  43         vfree(image->arch.dtb);
  44         image->arch.dtb = NULL;
  45
  46         vfree(image->arch.elf_headers);
  47         image->arch.elf_headers = NULL;
  48         image->arch.elf_headers_sz = 0;
  49
  50         return kexec_image_post_load_cleanup_default(image);
  51 }
  52
  53 static int setup_dtb(struct kimage *image,
  54                      unsigned long initrd_load_addr, unsigned long initrd_len,
  55                      char *cmdline, void *dtb)
  56 {
  57         int off, ret;
  58
  59         ret = fdt_path_offset(dtb, "/chosen");
  60         if (ret < 0)
  61                 goto out;
  62
  63         off = ret;
  64
  65         ret = fdt_delprop(dtb, off, FDT_PROP_KEXEC_ELFHDR);
  66         if (ret && ret != -FDT_ERR_NOTFOUND)
  67                 goto out;
  68         ret = fdt_delprop(dtb, off, FDT_PROP_MEM_RANGE);
  69         if (ret && ret != -FDT_ERR_NOTFOUND)
  70                 goto out;
  71
  72         if (image->type == KEXEC_TYPE_CRASH) {
  73                 /* add linux,elfcorehdr */
  74                 ret = fdt_appendprop_addrrange(dtb, 0, off,
  75                                 FDT_PROP_KEXEC_ELFHDR,
  76                                 image->arch.elf_headers_mem,
  77                                 image->arch.elf_headers_sz);
  78                 if (ret)
  79                         return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
  80
  81                 /* add linux,usable-memory-range */
  82                 ret = fdt_appendprop_addrrange(dtb, 0, off,
  83                                 FDT_PROP_MEM_RANGE,
  84                                 crashk_res.start,
  85                                 crashk_res.end - crashk_res.start + 1);
  86                 if (ret)
  87                         return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
  88         }
  89
  90         /* add bootargs */
  91         if (cmdline) {
  92                 ret = fdt_setprop_string(dtb, off, FDT_PROP_BOOTARGS, cmdline);
  93                 if (ret)
  94                         goto out;
  95         } else {
  96                 ret = fdt_delprop(dtb, off, FDT_PROP_BOOTARGS);
  97                 if (ret && (ret != -FDT_ERR_NOTFOUND))
  98                         goto out;
  99         }
 100
 101         /* add initrd-* */
 102         if (initrd_load_addr) {
 103                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_INITRD_START,
 104                                       initrd_load_addr);
 105                 if (ret)
 106                         goto out;
 107
 108                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_INITRD_END,
 109                                       initrd_load_addr + initrd_len);
 110                 if (ret)
 111                         goto out;
 112         } else {
 113                 ret = fdt_delprop(dtb, off, FDT_PROP_INITRD_START);
 114                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 115                         goto out;
 116
 117                 ret = fdt_delprop(dtb, off, FDT_PROP_INITRD_END);
 118                 if (ret && (ret != -FDT_ERR_NOTFOUND))
 119                         goto out;
 120         }
 121
 122         /* add kaslr-seed */
 123         ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
 124         if (ret == -FDT_ERR_NOTFOUND)
 125                 ret = 0;
 126         else if (ret)
 127                 goto out;
 128
 129         if (rng_is_initialized()) {
 130                 u64 seed = get_random_u64();
 131                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_KASLR_SEED, seed);
 132                 if (ret)
 133                         goto out;
 134         } else {
 135                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 136                                 FDT_PROP_KASLR_SEED);
 137         }
 138
 139         /* add rng-seed */
 140         if (rng_is_initialized()) {
 141                 void *rng_seed;
 142                 ret = fdt_setprop_placeholder(dtb, off, FDT_PROP_RNG_SEED,
 143                                 RNG_SEED_SIZE, &rng_seed);
 144                 if (ret)
 145                         goto out;
 146                 get_random_bytes(rng_seed, RNG_SEED_SIZE);
 147         } else {
 148                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 149                                 FDT_PROP_RNG_SEED);
 150         }
 151
 152 out:
 153         if (ret)
 154                 return (ret == -FDT_ERR_NOSPACE) ? -ENOMEM : -EINVAL;
 155
 156         return 0;
 157 }
 158
 159 /*
 160  * More space needed so that we can add initrd, bootargs, kaslr-seed,
 161  * rng-seed, userable-memory-range and elfcorehdr.
 162  */
 163 #define DTB_EXTRA_SPACE 0x1000
 164
 165 static int create_dtb(struct kimage *image,
 166                       unsigned long initrd_load_addr, unsigned long initrd_len,
 167                       char *cmdline, void **dtb)
 168 {
 169         void *buf;
 170         size_t buf_size;
 171         size_t cmdline_len;
 172         int ret;
 173
 174         cmdline_len = cmdline ? strlen(cmdline) : 0;
 175         buf_size = fdt_totalsize(initial_boot_params)
 176                         + cmdline_len + DTB_EXTRA_SPACE;
 177
 178         for (;;) {
 179                 buf = vmalloc(buf_size);
 180                 if (!buf)
 181                         return -ENOMEM;
 182
 183                 /* duplicate a device tree blob */
 184                 ret = fdt_open_into(initial_boot_params, buf, buf_size);
 185                 if (ret)
 186                         return -EINVAL;
 187
 188                 ret = setup_dtb(image, initrd_load_addr, initrd_len,
 189                                 cmdline, buf);
 190                 if (ret) {
 191                         vfree(buf);
 192                         if (ret == -ENOMEM) {
 193                                 /* unlikely, but just in case */
 194                                 buf_size += DTB_EXTRA_SPACE;
 195                                 continue;
 196                         } else {
 197                                 return ret;
 198                         }
 199                 }
 200
 201                 /* trim it */
 202                 fdt_pack(buf);
 203                 *dtb = buf;
 204
 205                 return 0;
 206         }
 207 }
 208
 209 static int prepare_elf_headers(void **addr, unsigned long *sz)
 210 {
 211         struct crash_mem *cmem;
 212         unsigned int nr_ranges;
 213         int ret;
 214         u64 i;
 215         phys_addr_t start, end;
 216
 217         nr_ranges = 1; /* for exclusion of crashkernel region */
 218         for_each_mem_range(i, &start, &end)
 219                 nr_ranges++;
 220
 221         cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
 222         if (!cmem)
 223                 return -ENOMEM;
 224
 225         cmem->max_nr_ranges = nr_ranges;
 226         cmem->nr_ranges = 0;
 227         for_each_mem_range(i, &start, &end) {
 228                 cmem->ranges[cmem->nr_ranges].start = start;
 229                 cmem->ranges[cmem->nr_ranges].end = end - 1;
 230                 cmem->nr_ranges++;
 231         }
 232
 233         /* Exclude crashkernel region */
 234         ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
 235
 236         if (!ret)
 237                 ret =  crash_prepare_elf64_headers(cmem, true, addr, sz);
 238
 239         kfree(cmem);
 240         return ret;
 241 }
 242
 243 /*
 244  * Tries to add the initrd and DTB to the image. If it is not possible to find
 245  * valid locations, this function will undo changes to the image and return non
 246  * zero.
 247  */
 248 int load_other_segments(struct kimage *image,
 249                         unsigned long kernel_load_addr,
 250                         unsigned long kernel_size,
 251                         char *initrd, unsigned long initrd_len,
 252                         char *cmdline)
 253 {
 254         struct kexec_buf kbuf;
 255         void *headers, *dtb = NULL;
 256         unsigned long headers_sz, initrd_load_addr = 0, dtb_len,
 257                       orig_segments = image->nr_segments;
 258         int ret = 0;
 259
 260         kbuf.image = image;
 261         /* not allocate anything below the kernel */
 262         kbuf.buf_min = kernel_load_addr + kernel_size;
 263
 264         /* load elf core header */
 265         if (image->type == KEXEC_TYPE_CRASH) {
 266                 ret = prepare_elf_headers(&headers, &headers_sz);
 267                 if (ret) {
 268                         pr_err("Preparing elf core header failed\n");
 269                         goto out_err;
 270                 }
 271
 272                 kbuf.buffer = headers;
 273                 kbuf.bufsz = headers_sz;
 274                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 275                 kbuf.memsz = headers_sz;
 276                 kbuf.buf_align = SZ_64K; /* largest supported page size */
 277                 kbuf.buf_max = ULONG_MAX;
 278                 kbuf.top_down = true;
 279
 280                 ret = kexec_add_buffer(&kbuf);
 281                 if (ret) {
 282                         vfree(headers);
 283                         goto out_err;
 284                 }
 285                 image->arch.elf_headers = headers;
 286                 image->arch.elf_headers_mem = kbuf.mem;
 287                 image->arch.elf_headers_sz = headers_sz;
 288
 289                 pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 290                          image->arch.elf_headers_mem, kbuf.bufsz, kbuf.memsz);
 291         }
 292
 293         /* load initrd */
 294         if (initrd) {
 295                 kbuf.buffer = initrd;
 296                 kbuf.bufsz = initrd_len;
 297                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 298                 kbuf.memsz = initrd_len;
 299                 kbuf.buf_align = 0;
 300                 /* within 1GB-aligned window of up to 32GB in size */
 301                 kbuf.buf_max = round_down(kernel_load_addr, SZ_1G)
 302                                                 + (unsigned long)SZ_1G * 32;
 303                 kbuf.top_down = false;
 304
 305                 ret = kexec_add_buffer(&kbuf);
 306                 if (ret)
 307                         goto out_err;
 308                 initrd_load_addr = kbuf.mem;
 309
 310                 pr_debug("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 311                                 initrd_load_addr, kbuf.bufsz, kbuf.memsz);
 312         }
 313
 314         /* load dtb */
 315         ret = create_dtb(image, initrd_load_addr, initrd_len, cmdline, &dtb);
 316         if (ret) {
 317                 pr_err("Preparing for new dtb failed\n");
 318                 goto out_err;
 319         }
 320
 321         dtb_len = fdt_totalsize(dtb);
 322         kbuf.buffer = dtb;
 323         kbuf.bufsz = dtb_len;
 324         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 325         kbuf.memsz = dtb_len;
 326         /* not across 2MB boundary */
 327         kbuf.buf_align = SZ_2M;
 328         kbuf.buf_max = ULONG_MAX;
 329         kbuf.top_down = true;
 330
 331         ret = kexec_add_buffer(&kbuf);
 332         if (ret)
 333                 goto out_err;
 334         image->arch.dtb = dtb;
 335         image->arch.dtb_mem = kbuf.mem;
 336
 337         pr_debug("Loaded dtb at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 338                         kbuf.mem, kbuf.bufsz, kbuf.memsz);
 339
 340         return 0;
 341
 342 out_err:
 343         image->nr_segments = orig_segments;
 344         vfree(dtb);
 345         return ret;
 346 }