Commit 55d990f0 authored by Youling Tang's avatar Youling Tang Committed by Huacai Chen
Browse files

LoongArch: Add EFI binary support for kexec_file 



This patch creates kexec_efi_ops to load EFI binary file for
kexec_file_load() syscall.

The efi_kexec_load() as two parts:
- the first part loads the kernel image (vmlinuz.efi or vmlinux.efi)
- the second part loads other segments (e.g: initrd, cmdline, etc)

Currently, pez (vmlinuz.efi) and pei (vmlinux.efi) format images are
supported.

The basic usage (vmlinuz.efi or vmlinux.efi):

1) Load second kernel image:
 # kexec -s -l vmlinuz.efi --initrd=initrd.img --reuse-cmdline

2) Startup second kernel:
 # kexec -e

Signed-off-by: default avatarYouling Tang <tangyouling@kylinos.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent d162feec

arch/loongarch/include/asm/image.h

+14 −0
Original line number Diff line number Diff line
@@ -33,6 +33,20 @@ struct loongarch_image_header { 
	uint32_t pe_header;

};



/*

 * loongarch_header_check_dos_sig - Helper to check the header

 *

 * Returns true (non-zero) if 'MZ' signature is found.

 */



static inline int loongarch_header_check_dos_sig(const struct loongarch_image_header *h)

{

	if (!h)

		return 0;



	return (h->dos_sig[0] == 'M' && h->dos_sig[1] == 'Z');

}



#endif /* __ASSEMBLER__ */



#endif /* __ASM_IMAGE_H */

arch/loongarch/include/asm/kexec.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ struct kimage_arch { 
};



#ifdef CONFIG_KEXEC_FILE

extern const struct kexec_file_ops kexec_efi_ops;



int arch_kimage_file_post_load_cleanup(struct kimage *image);

#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup

arch/loongarch/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -62,7 +62,7 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o 
obj-$(CONFIG_RELOCATABLE)	+= relocate.o



obj-$(CONFIG_KEXEC_CORE)	+= machine_kexec.o relocate_kernel.o

obj-$(CONFIG_KEXEC_FILE)	+= machine_kexec_file.o

obj-$(CONFIG_KEXEC_FILE)	+= machine_kexec_file.o kexec_efi.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o



obj-$(CONFIG_UNWINDER_GUESS)	+= unwind_guess.o

arch/loongarch/kernel/kexec_efi.c

0 → 100644
+113 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Load EFI vmlinux file for the kexec_file_load syscall.

 *

 * Author: Youling Tang <tangyouling@kylinos.cn>

 * Copyright (C) 2025 KylinSoft Corporation.

 */



#define pr_fmt(fmt)	"kexec_file(EFI): " fmt



#include <linux/err.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/kexec.h>

#include <linux/pe.h>

#include <linux/string.h>

#include <asm/byteorder.h>

#include <asm/cpufeature.h>

#include <asm/image.h>



static int efi_kexec_probe(const char *kernel_buf, unsigned long kernel_len)

{

	const struct loongarch_image_header *h = (const struct loongarch_image_header *)kernel_buf;



	if (!h || (kernel_len < sizeof(*h))) {

		kexec_dprintk("No LoongArch image header.\n");

		return -EINVAL;

	}



	if (!loongarch_header_check_dos_sig(h)) {

		kexec_dprintk("No LoongArch PE image header.\n");

		return -EINVAL;

	}



	return 0;

}



static void *efi_kexec_load(struct kimage *image,

				char *kernel, unsigned long kernel_len,

				char *initrd, unsigned long initrd_len,

				char *cmdline, unsigned long cmdline_len)

{

	int ret;

	unsigned long text_offset, kernel_segment_number;

	struct kexec_buf kbuf;

	struct kexec_segment *kernel_segment;

	struct loongarch_image_header *h;



	h = (struct loongarch_image_header *)kernel;

	if (!h->kernel_asize)

		return ERR_PTR(-EINVAL);



	/*

	 * Load the kernel

	 * FIXME: Non-relocatable kernel rejected for kexec_file (require CONFIG_RELOCATABLE)

	 */

	kbuf.image = image;

	kbuf.buf_max = ULONG_MAX;

	kbuf.top_down = false;



	kbuf.buffer = kernel;

	kbuf.bufsz = kernel_len;

	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;

	kbuf.memsz = le64_to_cpu(h->kernel_asize);

	text_offset = le64_to_cpu(h->text_offset);

	kbuf.buf_min = text_offset;

	kbuf.buf_align = SZ_2M;



	kernel_segment_number = image->nr_segments;



	/*

	 * The location of the kernel segment may make it impossible to

	 * satisfy the other segment requirements, so we try repeatedly

	 * to find a location that will work.

	 */

	while ((ret = kexec_add_buffer(&kbuf)) == 0) {

		/* Try to load additional data */

		kernel_segment = &image->segment[kernel_segment_number];

		ret = load_other_segments(image, kernel_segment->mem,

					  kernel_segment->memsz, initrd,

					  initrd_len, cmdline, cmdline_len);

		if (!ret)

			break;



		/*

		 * We couldn't find space for the other segments; erase the

		 * kernel segment and try the next available hole.

		 */

		image->nr_segments -= 1;

		kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz;

		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;

	}



	if (ret < 0) {

		pr_err("Could not find any suitable kernel location!");

		return ERR_PTR(ret);

	}



	kernel_segment = &image->segment[kernel_segment_number];



	/* Make sure the second kernel jumps to the correct "kernel_entry" */

	image->start = kernel_segment->mem + h->kernel_entry - text_offset;



	kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",

		      kernel_segment->mem, kbuf.bufsz, kernel_segment->memsz);



	return NULL;

}



const struct kexec_file_ops kexec_efi_ops = {

	.probe = efi_kexec_probe,

	.load = efi_kexec_load,

};

arch/loongarch/kernel/machine_kexec_file.c

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <asm/bootinfo.h>



const struct kexec_file_ops * const kexec_file_loaders[] = {

	&kexec_efi_ops,

	NULL

};