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Message-ID: <9760e574-3eb0-46b2-bccd-916f73b9c39e@linux.dev>
Date: Tue, 12 Aug 2025 09:21:25 +0800
From: Youling Tang <youling.tang@...ux.dev>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: WANG Xuerui <kernel@...0n.name>, Baoquan He <bhe@...hat.com>,
kexec@...ts.infradead.org, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, Youling Tang <tangyouling@...inos.cn>
Subject: Re: [PATCH 2/6] LoongArch: Add kexec_file support
Hi, Huacai
On 2025/8/11 22:07, Huacai Chen wrote:
> Hi, Youling,
>
> On Mon, Aug 11, 2025 at 5:28 PM Youling Tang <youling.tang@...ux.dev> wrote:
>> From: Youling Tang <tangyouling@...inos.cn>
>>
>> This patch adds support for kexec_file on LoongArch.
>>
>> The image_load() as two parts:
>> - the first part loads the kernel image (vmlinuz.efi or vmlinux.efi)
>> - the second part loads other segments (eg: initrd, cmdline)
>>
>> Currently, pez(vmlinuz.efi) and pei(vmlinux.efi) format images are supported,
>> but ELF format is not supported.
>>
>> Signed-off-by: Youling Tang <tangyouling@...inos.cn>
>> ---
>> arch/loongarch/Kconfig | 8 ++
>> arch/loongarch/include/asm/image.h | 18 ++++
>> arch/loongarch/include/asm/kexec.h | 12 +++
>> arch/loongarch/kernel/Makefile | 1 +
>> arch/loongarch/kernel/kexec_image.c | 112 +++++++++++++++++++++
>> arch/loongarch/kernel/machine_kexec.c | 33 ++++--
>> arch/loongarch/kernel/machine_kexec_file.c | 46 +++++++++
>> 7 files changed, 219 insertions(+), 11 deletions(-)
>> create mode 100644 arch/loongarch/kernel/kexec_image.c
>> create mode 100644 arch/loongarch/kernel/machine_kexec_file.c
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index f0abc38c40ac..fd50c83f7827 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -625,6 +625,14 @@ config CPU_HAS_PREFETCH
>> config ARCH_SUPPORTS_KEXEC
>> def_bool y
>>
>> +config ARCH_SUPPORTS_KEXEC_FILE
>> + def_bool 64BIT
>> +
>> +config ARCH_SELECTS_KEXEC_FILE
>> + def_bool y
>> + depends on KEXEC_FILE
>> + select HAVE_IMA_KEXEC if IMA
>> +
>> config ARCH_SUPPORTS_CRASH_DUMP
>> def_bool y
>>
>> diff --git a/arch/loongarch/include/asm/image.h b/arch/loongarch/include/asm/image.h
>> index 1f090736e71d..829e1ecb1f5d 100644
>> --- a/arch/loongarch/include/asm/image.h
>> +++ b/arch/loongarch/include/asm/image.h
>> @@ -36,5 +36,23 @@ struct loongarch_image_header {
>> uint32_t pe_header;
>> };
>>
>> +static const uint8_t loongarch_image_pe_sig[2] = {'M', 'Z'};
>> +static const uint8_t loongarch_pe_machtype[6] = {'P', 'E', 0x0, 0x0, 0x64, 0x62};
>> +
>> +/**
>> + * loongarch_header_check_pe_sig - Helper to check the loongarch image header.
>> + *
>> + * Returns non-zero if 'MZ' signature is found.
>> + */
>> +
>> +static inline int loongarch_header_check_pe_sig(const struct loongarch_image_header *h)
>> +{
>> + if (!h)
>> + return 0;
>> +
>> + return (h->pe_sig[0] == loongarch_image_pe_sig[0]
>> + && h->pe_sig[1] == loongarch_image_pe_sig[1]);
>> +}
>> +
>> #endif /* __ASSEMBLY__ */
>> #endif /* __ASM_IMAGE_H */
>> diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
>> index cf95cd3eb2de..3ef8517a3670 100644
>> --- a/arch/loongarch/include/asm/kexec.h
>> +++ b/arch/loongarch/include/asm/kexec.h
>> @@ -41,6 +41,18 @@ struct kimage_arch {
>> unsigned long systable_ptr;
>> };
>>
>> +#ifdef CONFIG_KEXEC_FILE
>> +extern const struct kexec_file_ops kexec_image_ops;
>> +
>> +int arch_kimage_file_post_load_cleanup(struct kimage *image);
>> +#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup
>> +
>> +extern int load_other_segments(struct kimage *image,
>> + unsigned long kernel_load_addr, unsigned long kernel_size,
>> + char *initrd, unsigned long initrd_len,
>> + char *cmdline, unsigned long cmdline_len);
> I think the RISC-V naming "load_extra_segments" is better.
This name is also fine, but I prefer it to be consistent with
that in kexec-tools.
>
>> +#endif
>> +
>> typedef void (*do_kexec_t)(unsigned long efi_boot,
>> unsigned long cmdline_ptr,
>> unsigned long systable_ptr,
>> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
>> index 6f5a4574a911..bd9405ee3888 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -62,6 +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 kexec_image.o
> We only support the efi format, so we don't need to split a
> kexec_image.c like RISC-V, just put everything into
> machine_kexec_file.c is OK.
I hope it is separated and consistent with other architectures.
For instance, arm64 only supports one type.
Youling.
>
> Huacai
>
>> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>>
>> obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>> diff --git a/arch/loongarch/kernel/kexec_image.c b/arch/loongarch/kernel/kexec_image.c
>> new file mode 100644
>> index 000000000000..fdd1845b4e2e
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/kexec_image.c
>> @@ -0,0 +1,112 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Kexec image loader for LoongArch
>> +
>> + * Author: Youling Tang <tangyouling@...inos.cn>
>> + * Copyright (C) 2025 KylinSoft Corporation.
>> + */
>> +
>> +#define pr_fmt(fmt) "kexec_file(Image): " 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 image_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))) {
>> + pr_err("No loongarch image header.\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (!loongarch_header_check_pe_sig(h)) {
>> + pr_err("Bad loongarch PE image header.\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void *image_load(struct kimage *image,
>> + char *kernel, unsigned long kernel_len,
>> + char *initrd, unsigned long initrd_len,
>> + char *cmdline, unsigned long cmdline_len)
>> +{
>> + struct loongarch_image_header *h;
>> + struct kexec_buf kbuf;
>> + unsigned long text_offset, kernel_segment_number;
>> + struct kexec_segment *kernel_segment;
>> + int ret;
>> +
>> + h = (struct loongarch_image_header *)kernel;
>> + if (!h->image_size)
>> + return ERR_PTR(-EINVAL);
>> +
>> + /* Load the kernel */
>> + kbuf.image = image;
>> + kbuf.buf_min = 0;
>> + 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->image_size);
>> + text_offset = le64_to_cpu(h->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) {
>> + 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_image_ops = {
>> + .probe = image_probe,
>> + .load = image_load,
>> +};
>> diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
>> index f9381800e291..008f43e26120 100644
>> --- a/arch/loongarch/kernel/machine_kexec.c
>> +++ b/arch/loongarch/kernel/machine_kexec.c
>> @@ -70,18 +70,28 @@ int machine_kexec_prepare(struct kimage *kimage)
>> kimage->arch.efi_boot = fw_arg0;
>> kimage->arch.systable_ptr = fw_arg2;
>>
>> - /* Find the command line */
>> - for (i = 0; i < kimage->nr_segments; i++) {
>> - if (!strncmp(bootloader, (char __user *)kimage->segment[i].buf, strlen(bootloader))) {
>> - if (!copy_from_user(cmdline_ptr, kimage->segment[i].buf, COMMAND_LINE_SIZE))
>> - kimage->arch.cmdline_ptr = (unsigned long)cmdline_ptr;
>> - break;
>> + if (kimage->file_mode == 1) {
>> + /*
>> + * kimage->cmdline_buf will be released in kexec_file_load, so copy to
>> + * the KEXEC_CMDLINE_ADDR safe area.
>> + */
>> + memcpy((void *)KEXEC_CMDLINE_ADDR, (void *)kimage->arch.cmdline_ptr,
>> + strlen((char *)kimage->arch.cmdline_ptr) + 1);
>> + kimage->arch.cmdline_ptr = (unsigned long)KEXEC_CMDLINE_ADDR;
>> + } else {
>> + /* Find the command line */
>> + for (i = 0; i < kimage->nr_segments; i++) {
>> + if (!strncmp(bootloader, (char __user *)kimage->segment[i].buf, strlen(bootloader))) {
>> + if (!copy_from_user(cmdline_ptr, kimage->segment[i].buf, COMMAND_LINE_SIZE))
>> + kimage->arch.cmdline_ptr = (unsigned long)cmdline_ptr;
>> + break;
>> + }
>> }
>> - }
>>
>> - if (!kimage->arch.cmdline_ptr) {
>> - pr_err("Command line not included in the provided image\n");
>> - return -EINVAL;
>> + if (!kimage->arch.cmdline_ptr) {
>> + pr_err("Command line not included in the provided image\n");
>> + return -EINVAL;
>> + }
>> }
>>
>> /* kexec/kdump need a safe page to save reboot_code_buffer */
>> @@ -288,7 +298,8 @@ void machine_kexec(struct kimage *image)
>> local_irq_disable();
>>
>> pr_notice("EFI boot flag 0x%lx\n", efi_boot);
>> - pr_notice("Command line at 0x%lx\n", cmdline_ptr);
>> + pr_notice("Command line addr at 0x%lx\n", cmdline_ptr);
>> + pr_notice("Command line at %s\n", (char *)cmdline_ptr);
>> pr_notice("System table at 0x%lx\n", systable_ptr);
>> pr_notice("We will call new kernel at 0x%lx\n", start_addr);
>> pr_notice("Bye ...\n");
>> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
>> new file mode 100644
>> index 000000000000..bc91ae0afa4c
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/machine_kexec_file.c
>> @@ -0,0 +1,46 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * kexec_file for LoongArch
>> + *
>> + * Author: Youling Tang <tangyouling@...inos.cn>
>> + * Copyright (C) 2025 KylinSoft Corporation.
>> + *
>> + * Most code is derived from LoongArch port of kexec-tools
>> + */
>> +
>> +#define pr_fmt(fmt) "kexec_file: " fmt
>> +
>> +#include <linux/ioport.h>
>> +#include <linux/kernel.h>
>> +#include <linux/kexec.h>
>> +#include <linux/memblock.h>
>> +#include <linux/slab.h>
>> +#include <linux/string.h>
>> +#include <linux/types.h>
>> +#include <linux/vmalloc.h>
>> +#include <asm/bootinfo.h>
>> +
>> +const struct kexec_file_ops * const kexec_file_loaders[] = {
>> + &kexec_image_ops,
>> + NULL
>> +};
>> +
>> +int arch_kimage_file_post_load_cleanup(struct kimage *image)
>> +{
>> + vfree(image->elf_headers);
>> + image->elf_headers = NULL;
>> + image->elf_headers_sz = 0;
>> +
>> + return kexec_image_post_load_cleanup_default(image);
>> +}
>> +
>> +int load_other_segments(struct kimage *image,
>> + unsigned long kernel_load_addr,
>> + unsigned long kernel_size,
>> + char *initrd, unsigned long initrd_len,
>> + char *cmdline, unsigned long cmdline_len)
>> +{
>> + image->arch.cmdline_ptr = (unsigned long)cmdline;
>> +
>> + return 0;
>> +}
>> --
>> 2.34.1
>>
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