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
 22static 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
 36static 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
132const 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};