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

[Youling Tang]

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.t...@linux.dev> wrote:

From: Youling Tang <tangyoul...@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 <tangyoul...@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.

Thanks,
Youling.

Thanks,
Yanteng

Youling.

Huacai