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/string.h>
  21 #include <linux/types.h>
  22 #include <linux/vmalloc.h>
  23 #include <asm/byteorder.h>
  24
  25 /* relevant device tree properties */
  26 #define FDT_PROP_INITRD_START   "linux,initrd-start"
  27 #define FDT_PROP_INITRD_END     "linux,initrd-end"
  28 #define FDT_PROP_BOOTARGS       "bootargs"
  29 #define FDT_PROP_KASLR_SEED     "kaslr-seed"
  30 #define FDT_PROP_RNG_SEED       "rng-seed"
  31 #define RNG_SEED_SIZE           128
  32
  33 const struct kexec_file_ops * const kexec_file_loaders[] = {
  34         &kexec_image_ops,
  35         NULL
  36 };
  37
  38 int arch_kimage_file_post_load_cleanup(struct kimage *image)
  39 {
  40         vfree(image->arch.dtb);
  41         image->arch.dtb = NULL;
  42
  43         return kexec_image_post_load_cleanup_default(image);
  44 }
  45
  46 static int setup_dtb(struct kimage *image,
  47                      unsigned long initrd_load_addr, unsigned long initrd_len,
  48                      char *cmdline, void *dtb)
  49 {
  50         int off, ret;
  51
  52         ret = fdt_path_offset(dtb, "/chosen");
  53         if (ret < 0)
  54                 goto out;
  55
  56         off = ret;
  57
  58         /* add bootargs */
  59         if (cmdline) {
  60                 ret = fdt_setprop_string(dtb, off, FDT_PROP_BOOTARGS, cmdline);
  61                 if (ret)
  62                         goto out;
  63         } else {
  64                 ret = fdt_delprop(dtb, off, FDT_PROP_BOOTARGS);
  65                 if (ret && (ret != -FDT_ERR_NOTFOUND))
  66                         goto out;
  67         }
  68
  69         /* add initrd-* */
  70         if (initrd_load_addr) {
  71                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_INITRD_START,
  72                                       initrd_load_addr);
  73                 if (ret)
  74                         goto out;
  75
  76                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_INITRD_END,
  77                                       initrd_load_addr + initrd_len);
  78                 if (ret)
  79                         goto out;
  80         } else {
  81                 ret = fdt_delprop(dtb, off, FDT_PROP_INITRD_START);
  82                 if (ret && (ret != -FDT_ERR_NOTFOUND))
  83                         goto out;
  84
  85                 ret = fdt_delprop(dtb, off, FDT_PROP_INITRD_END);
  86                 if (ret && (ret != -FDT_ERR_NOTFOUND))
  87                         goto out;
  88         }
  89
  90         /* add kaslr-seed */
  91         ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
  92         if  (ret == -FDT_ERR_NOTFOUND)
  93                 ret = 0;
  94         else if (ret)
  95                 goto out;
  96
  97         if (rng_is_initialized()) {
  98                 u64 seed = get_random_u64();
  99                 ret = fdt_setprop_u64(dtb, off, FDT_PROP_KASLR_SEED, seed);
 100                 if (ret)
 101                         goto out;
 102         } else {
 103                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 104                                 FDT_PROP_KASLR_SEED);
 105         }
 106
 107         /* add rng-seed */
 108         if (rng_is_initialized()) {
 109                 u8 rng_seed[RNG_SEED_SIZE];
 110                 get_random_bytes(rng_seed, RNG_SEED_SIZE);
 111                 ret = fdt_setprop(dtb, off, FDT_PROP_RNG_SEED, rng_seed,
 112                                 RNG_SEED_SIZE);
 113                 if (ret)
 114                         goto out;
 115         } else {
 116                 pr_notice("RNG is not initialised: omitting \"%s\" property\n",
 117                                 FDT_PROP_RNG_SEED);
 118         }
 119
 120 out:
 121         if (ret)
 122                 return (ret == -FDT_ERR_NOSPACE) ? -ENOMEM : -EINVAL;
 123
 124         return 0;
 125 }
 126
 127 /*
 128  * More space needed so that we can add initrd, bootargs, kaslr-seed, and
 129  * rng-seed.
 130  */
 131 #define DTB_EXTRA_SPACE 0x1000
 132
 133 static int create_dtb(struct kimage *image,
 134                       unsigned long initrd_load_addr, unsigned long initrd_len,
 135                       char *cmdline, void **dtb)
 136 {
 137         void *buf;
 138         size_t buf_size;
 139         size_t cmdline_len;
 140         int ret;
 141
 142         cmdline_len = cmdline ? strlen(cmdline) : 0;
 143         buf_size = fdt_totalsize(initial_boot_params)
 144                         + cmdline_len + DTB_EXTRA_SPACE;
 145
 146         for (;;) {
 147                 buf = vmalloc(buf_size);
 148                 if (!buf)
 149                         return -ENOMEM;
 150
 151                 /* duplicate a device tree blob */
 152                 ret = fdt_open_into(initial_boot_params, buf, buf_size);
 153                 if (ret)
 154                         return -EINVAL;
 155
 156                 ret = setup_dtb(image, initrd_load_addr, initrd_len,
 157                                 cmdline, buf);
 158                 if (ret) {
 159                         vfree(buf);
 160                         if (ret == -ENOMEM) {
 161                                 /* unlikely, but just in case */
 162                                 buf_size += DTB_EXTRA_SPACE;
 163                                 continue;
 164                         } else {
 165                                 return ret;
 166                         }
 167                 }
 168
 169                 /* trim it */
 170                 fdt_pack(buf);
 171                 *dtb = buf;
 172
 173                 return 0;
 174         }
 175 }
 176
 177 int load_other_segments(struct kimage *image,
 178                         unsigned long kernel_load_addr,
 179                         unsigned long kernel_size,
 180                         char *initrd, unsigned long initrd_len,
 181                         char *cmdline)
 182 {
 183         struct kexec_buf kbuf;
 184         void *dtb = NULL;
 185         unsigned long initrd_load_addr = 0, dtb_len;
 186         int ret = 0;
 187
 188         kbuf.image = image;
 189         /* not allocate anything below the kernel */
 190         kbuf.buf_min = kernel_load_addr + kernel_size;
 191
 192         /* load initrd */
 193         if (initrd) {
 194                 kbuf.buffer = initrd;
 195                 kbuf.bufsz = initrd_len;
 196                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 197                 kbuf.memsz = initrd_len;
 198                 kbuf.buf_align = 0;
 199                 /* within 1GB-aligned window of up to 32GB in size */
 200                 kbuf.buf_max = round_down(kernel_load_addr, SZ_1G)
 201                                                 + (unsigned long)SZ_1G * 32;
 202                 kbuf.top_down = false;
 203
 204                 ret = kexec_add_buffer(&kbuf);
 205                 if (ret)
 206                         goto out_err;
 207                 initrd_load_addr = kbuf.mem;
 208
 209                 pr_debug("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 210                                 initrd_load_addr, initrd_len, initrd_len);
 211         }
 212
 213         /* load dtb */
 214         ret = create_dtb(image, initrd_load_addr, initrd_len, cmdline, &dtb);
 215         if (ret) {
 216                 pr_err("Preparing for new dtb failed\n");
 217                 goto out_err;
 218         }
 219
 220         dtb_len = fdt_totalsize(dtb);
 221         kbuf.buffer = dtb;
 222         kbuf.bufsz = dtb_len;
 223         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 224         kbuf.memsz = dtb_len;
 225         /* not across 2MB boundary */
 226         kbuf.buf_align = SZ_2M;
 227         kbuf.buf_max = ULONG_MAX;
 228         kbuf.top_down = true;
 229
 230         ret = kexec_add_buffer(&kbuf);
 231         if (ret)
 232                 goto out_err;
 233         image->arch.dtb = dtb;
 234         image->arch.dtb_mem = kbuf.mem;
 235
 236         pr_debug("Loaded dtb at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 237                         kbuf.mem, dtb_len, dtb_len);
 238
 239         return 0;
 240
 241 out_err:
 242         vfree(dtb);
 243         return ret;
 244 }