arch/arm64/kernel/kexec_image.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Kexec image loader
   4
   5  * Copyright (C) 2018 Linaro Limited
   6  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
   7  */
   8
   9 #define pr_fmt(fmt)     "kexec_file(Image): " fmt
  10
  11 #include <linux/err.h>
  12 #include <linux/errno.h>
  13 #include <linux/kernel.h>
  14 #include <linux/kexec.h>
  15 #include <linux/pe.h>
  16 #include <linux/string.h>
  17 #include <linux/verification.h>
  18 #include <asm/byteorder.h>
  19 #include <asm/cpufeature.h>
  20 #include <asm/image.h>
  21 #include <asm/memory.h>
  22
  23 static int image_probe(const char *kernel_buf, unsigned long kernel_len)
  24 {
  25         const struct arm64_image_header *h =
  26                 (const struct arm64_image_header *)(kernel_buf);
  27
  28         if (!h || (kernel_len < sizeof(*h)))
  29                 return -EINVAL;
  30
  31         if (memcmp(&h->magic, ARM64_IMAGE_MAGIC, sizeof(h->magic)))
  32                 return -EINVAL;
  33
  34         return 0;
  35 }
  36
  37 static void *image_load(struct kimage *image,
  38                                 char *kernel, unsigned long kernel_len,
  39                                 char *initrd, unsigned long initrd_len,
  40                                 char *cmdline, unsigned long cmdline_len)
  41 {
  42         struct arm64_image_header *h;
  43         u64 flags, value;
  44         bool be_image, be_kernel;
  45         struct kexec_buf kbuf;
  46         unsigned long text_offset, kernel_segment_number;
  47         struct kexec_segment *kernel_segment;
  48         int ret;
  49
  50         /*
  51          * We require a kernel with an unambiguous Image header. Per
  52          * Documentation/arm64/booting.rst, this is the case when image_size
  53          * is non-zero (practically speaking, since v3.17).
  54          */
  55         h = (struct arm64_image_header *)kernel;
  56         if (!h->image_size)
  57                 return ERR_PTR(-EINVAL);
  58
  59         /* Check cpu features */
  60         flags = le64_to_cpu(h->flags);
  61         be_image = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_BE);
  62         be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
  63         if ((be_image != be_kernel) && !system_supports_mixed_endian())
  64                 return ERR_PTR(-EINVAL);
  65
  66         value = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_PAGE_SIZE);
  67         if (((value == ARM64_IMAGE_FLAG_PAGE_SIZE_4K) &&
  68                         !system_supports_4kb_granule()) ||
  69             ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_64K) &&
  70                         !system_supports_64kb_granule()) ||
  71             ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_16K) &&
  72                         !system_supports_16kb_granule()))
  73                 return ERR_PTR(-EINVAL);
  74
  75         /* Load the kernel */
  76         kbuf.image = image;
  77         kbuf.buf_min = 0;
  78         kbuf.buf_max = ULONG_MAX;
  79         kbuf.top_down = false;
  80
  81         kbuf.buffer = kernel;
  82         kbuf.bufsz = kernel_len;
  83         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
  84         kbuf.memsz = le64_to_cpu(h->image_size);
  85         text_offset = le64_to_cpu(h->text_offset);
  86         kbuf.buf_align = MIN_KIMG_ALIGN;
  87
  88         /* Adjust kernel segment with TEXT_OFFSET */
  89         kbuf.memsz += text_offset;
  90
  91         kernel_segment_number = image->nr_segments;
  92
  93         /*
  94          * The location of the kernel segment may make it impossible to satisfy
  95          * the other segment requirements, so we try repeatedly to find a
  96          * location that will work.
  97          */
  98         while ((ret = kexec_add_buffer(&kbuf)) == 0) {
  99                 /* Try to load additional data */
 100                 kernel_segment = &image->segment[kernel_segment_number];
 101                 ret = load_other_segments(image, kernel_segment->mem,
 102                                           kernel_segment->memsz, initrd,
 103                                           initrd_len, cmdline);
 104                 if (!ret)
 105                         break;
 106
 107                 /*
 108                  * We couldn't find space for the other segments; erase the
 109                  * kernel segment and try the next available hole.
 110                  */
 111                 image->nr_segments -= 1;
 112                 kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz;
 113                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 114         }
 115
 116         if (ret) {
 117                 pr_err("Could not find any suitable kernel location!");
 118                 return ERR_PTR(ret);
 119         }
 120
 121         kernel_segment = &image->segment[kernel_segment_number];
 122         kernel_segment->mem += text_offset;
 123         kernel_segment->memsz -= text_offset;
 124         image->start = kernel_segment->mem;
 125
 126         pr_debug("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 127                                 kernel_segment->mem, kbuf.bufsz,
 128                                 kernel_segment->memsz);
 129
 130         return NULL;
 131 }
 132
 133 #ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
 134 static int image_verify_sig(const char *kernel, unsigned long kernel_len)
 135 {
 136         return verify_pefile_signature(kernel, kernel_len, NULL,
 137                                        VERIFYING_KEXEC_PE_SIGNATURE);
 138 }
 139 #endif
 140
 141 const struct kexec_file_ops kexec_image_ops = {
 142         .probe = image_probe,
 143         .load = image_load,
 144 #ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
 145         .verify_sig = image_verify_sig,
 146 #endif
 147 };