linux-kernel - Re: [PATCH 2/6] LoongArch: Add kexec

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Message-ID: <ce63aa14-11a5-4b2c-bfbc-8465b7065197@linux.dev>
Date: Tue, 12 Aug 2025 09:53:25 +0800
From: Yanteng Si <si.yanteng@...ux.dev>
To: Youling Tang <youling.tang@...ux.dev>, 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

在 8/12/25 9:21 AM, Youling Tang 写道:
> 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.
I have looked at the code of kexec-tools, and it seems that you referenced a great deal of ARM code when implementing the LoongArch part.


>>
>>> +#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.
The ARM64 architecture has a long history, and we shouldn't be constrained by it.


Thanks,
Yanteng
>
> Youling.
>>
>> Huacai