Re: [PATCH 2/6] LoongArch: Add kexec_file support

[Yanteng Si <si.yanteng@linux.dev>]

在 8/12/25 5:32 PM, Youling Tang 写道:
> Hi, Yanteng
> On 2025/8/12 09:53, Yanteng Si wrote:
>> 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@linux.dev> wrote:
>>>>> From: Youling Tang <tangyouling@kylinos.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@kylinos.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.
> Support for kexec_elf.c in ELF format may be considered for
> addition in the future.

Ok, I see.


Thanks,

Yanteng

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