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// SPDX-License-Identifier: GPL-2.0-only
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/*
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 * Load ELF vmlinux file for the kexec_file_load syscall.
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 *
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 * Author: Youling Tang <[email protected]>
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 * Copyright (C) 2025 KylinSoft Corporation.
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 */
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#define pr_fmt(fmt)	"kexec_file(ELF): " fmt
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#include <linux/elf.h>
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#include <linux/kexec.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/memblock.h>
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#include <asm/setup.h>
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#define elf_kexec_probe kexec_elf_probe
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static int _elf_kexec_load(struct kimage *image,
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			   struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
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			   struct kexec_buf *kbuf, unsigned long *text_offset)
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{
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	int i, ret = -1;
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	/* Read in the PT_LOAD segments. */
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	for (i = 0; i < ehdr->e_phnum; i++) {
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		size_t size;
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		const struct elf_phdr *phdr;
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		phdr = &elf_info->proghdrs[i];
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		if (phdr->p_type != PT_LOAD)
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			continue;
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		size = phdr->p_filesz;
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		if (size > phdr->p_memsz)
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			size = phdr->p_memsz;
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		kbuf->buffer = (void *)elf_info->buffer + phdr->p_offset;
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		kbuf->bufsz = size;
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		kbuf->buf_align = phdr->p_align;
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		*text_offset = __pa(phdr->p_paddr);
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		kbuf->buf_min = *text_offset;
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		kbuf->memsz = ALIGN(phdr->p_memsz, SZ_64K);
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		kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
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		ret = kexec_add_buffer(kbuf);
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		if (ret < 0)
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			break;
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	}
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	return ret;
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}
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static void *elf_kexec_load(struct kimage *image,
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			    char *kernel, unsigned long kernel_len,
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			    char *initrd, unsigned long initrd_len,
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			    char *cmdline, unsigned long cmdline_len)
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{
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	int ret;
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	unsigned long text_offset, kernel_segment_number;
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	struct elfhdr ehdr;
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	struct kexec_buf kbuf;
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	struct kexec_elf_info elf_info;
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	struct kexec_segment *kernel_segment;
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	ret = kexec_build_elf_info(kernel, kernel_len, &ehdr, &elf_info);
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	if (ret < 0)
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		return ERR_PTR(ret);
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	/*
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	 * Load the kernel
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	 * FIXME: Non-relocatable kernel rejected for kexec_file (require CONFIG_RELOCATABLE)
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	 */
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	kbuf.image = image;
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	kbuf.buf_max = ULONG_MAX;
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	kbuf.top_down = false;
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	kernel_segment_number = image->nr_segments;
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	ret = _elf_kexec_load(image, &ehdr, &elf_info, &kbuf, &text_offset);
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	if (ret < 0)
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		goto out;
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	/* Load additional data */
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	kernel_segment = &image->segment[kernel_segment_number];
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	ret = load_other_segments(image, kernel_segment->mem, kernel_segment->memsz,
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				  initrd, initrd_len, cmdline, cmdline_len);
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	if (ret < 0)
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		goto out;
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	/* Make sure the second kernel jumps to the correct "kernel_entry". */
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	image->start = kernel_segment->mem + __pa(ehdr.e_entry) - text_offset;
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	kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
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		      kernel_segment->mem, kbuf.bufsz, kernel_segment->memsz);
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out:
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	kexec_free_elf_info(&elf_info);
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	return ret ? ERR_PTR(ret) : NULL;
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}
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const struct kexec_file_ops kexec_elf_ops = {
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	.probe = elf_kexec_probe,
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	.load  = elf_kexec_load,
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};
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