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