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