kexec_efi.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Load EFI vmlinux file for the kexec_file_load syscall.
  4 *
  5 * Author: Youling Tang <tangyouling@kylinos.cn>
  6 * Copyright (C) 2025 KylinSoft Corporation.
  7 */
  8
  9#define pr_fmt(fmt)	"kexec_file(EFI): " 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
 21static int efi_kexec_probe(const char *kernel_buf, unsigned long kernel_len)
 22{
 23	const struct loongarch_image_header *h = (const struct loongarch_image_header *)kernel_buf;
 24
 25	if (!h || (kernel_len < sizeof(*h))) {
 26		kexec_dprintk("No LoongArch image header.\n");
 27		return -EINVAL;
 28	}
 29
 30	if (!loongarch_header_check_dos_sig(h)) {
 31		kexec_dprintk("No LoongArch PE image header.\n");
 32		return -EINVAL;
 33	}
 34
 35	return 0;
 36}
 37
 38static void *efi_kexec_load(struct kimage *image,
 39				char *kernel, unsigned long kernel_len,
 40				char *initrd, unsigned long initrd_len,
 41				char *cmdline, unsigned long cmdline_len)
 42{
 43	int ret;
 44	unsigned long text_offset, kernel_segment_number;
 45	struct kexec_buf kbuf = {};
 46	struct kexec_segment *kernel_segment;
 47	struct loongarch_image_header *h;
 48
 49	h = (struct loongarch_image_header *)kernel;
 50	if (!h->kernel_asize)
 51		return ERR_PTR(-EINVAL);
 52
 53	/*
 54	 * Load the kernel
 55	 * FIXME: Non-relocatable kernel rejected for kexec_file (require CONFIG_RELOCATABLE)
 56	 */
 57	kbuf.image = image;
 58	kbuf.buf_max = ULONG_MAX;
 59	kbuf.top_down = false;
 60
 61	kbuf.buffer = kernel;
 62	kbuf.bufsz = kernel_len;
 63	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 64	kbuf.memsz = le64_to_cpu(h->kernel_asize);
 65	text_offset = le64_to_cpu(h->text_offset);
 66	kbuf.buf_min = text_offset;
 67	kbuf.buf_align = SZ_2M;
 68
 69	kernel_segment_number = image->nr_segments;
 70
 71	/*
 72	 * The location of the kernel segment may make it impossible to
 73	 * satisfy the other segment requirements, so we try repeatedly
 74	 * to find a location that will work.
 75	 */
 76	while ((ret = kexec_add_buffer(&kbuf)) == 0) {
 77		/* Try to load additional data */
 78		kernel_segment = &image->segment[kernel_segment_number];
 79		ret = load_other_segments(image, kernel_segment->mem,
 80					  kernel_segment->memsz, initrd,
 81					  initrd_len, cmdline, cmdline_len);
 82		if (!ret)
 83			break;
 84
 85		/*
 86		 * We couldn't find space for the other segments; erase the
 87		 * kernel segment and try the next available hole.
 88		 */
 89		image->nr_segments -= 1;
 90		kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz;
 91		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 92	}
 93
 94	if (ret < 0) {
 95		pr_err("Could not find any suitable kernel location!");
 96		return ERR_PTR(ret);
 97	}
 98
 99	kernel_segment = &image->segment[kernel_segment_number];
100
101	/* Make sure the second kernel jumps to the correct "kernel_entry" */
102	image->start = kernel_segment->mem + h->kernel_entry - text_offset;
103
104	kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
105		      kernel_segment->mem, kbuf.bufsz, kernel_segment->memsz);
106
107	return NULL;
108}
109
110const struct kexec_file_ops kexec_efi_ops = {
111	.probe = efi_kexec_probe,
112	.load = efi_kexec_load,
113};