LXR linux/arch/arm64/kernel/kexec

   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
  23static 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
  37static 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
 134static 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
 141const 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};
 148