[PATCH v3 0/6] Add kexec_file support for LoongArch

[Youling Tang <youling.tang@linux.dev>]

From: Youling Tang <tangyouling@kylinos.cn>

This patchset implement kexec_file_load() support on LoongArch.

This patch series enables us to load the LoongArch vmlinuz.efi(pez) or
vmlinux.efi(pei) or vmlinux(elf) by specifying its file decriptor,
instead of user-filled buffer via kexec_load() syscall.

To use kexec_file_load() system call, instead of kexec_load(), at kexec
command, '-s' options must be specified. kexec-tools needs to apply the
corresponding patches. These patches can be found in repository [1] and
will be submitted to the kexec-tools community later.

The basic usage of kexec_file is:
1) Load second kernel image:
 # kexec -s -l vmlinuz.efi --initrd=initrd.img --reuse-cmdline

2) Startup second kernel:
 # kexec -e

For kdump:
1) Load capture kernel image:
 # kexec -s -p vmlinuz.efi --initrd=initrd.img --reuse-cmdline

2) Do something to crash, like:
 # echo c > /proc/sysrq-trigger

Link:
[1] https://github.com/tangyouling/kexec-tools/commits/main/

Changelog:
 v3:
 * The ELF format kernel loading should not use loongarch_image_header. 
 * Separate patch2 into an infrastructure patch and an EFI support
   patch.
 * Adding that kexec_file cannot load non-relocation kernel comments.
 * Some minor modifications.

 v2:
 * Merge some patches.
 * Add support for ELF format images.
 * Rename kexec_image.c to kexec_efi.c .
 * When KEXEC_FILE is enabled, RELOCATABLE is selected by default.
 * Some minor modifications.

Youling Tang (6):
  LoongArch: Add struct loongarch_image_header for kernel image
  LoongArch: Add preparatory infrastructure for kexec_file
  LoongArch/kexec_file: Support loading EFI binary file
  LoongArch/kexec_file: Support loading ELF binary file
  LoongArch/kexec_file: Add crash dump support
  LoongArch: Enable CONFIG_KEXEC_FILE

 arch/loongarch/Kconfig                     |  10 +
 arch/loongarch/configs/loongson3_defconfig |   1 +
 arch/loongarch/include/asm/image.h         |  57 +++++
 arch/loongarch/include/asm/kexec.h         |  13 ++
 arch/loongarch/kernel/Makefile             |   1 +
 arch/loongarch/kernel/kexec_efi.c          | 114 ++++++++++
 arch/loongarch/kernel/kexec_elf.c          | 105 +++++++++
 arch/loongarch/kernel/machine_kexec.c      |  37 ++--
 arch/loongarch/kernel/machine_kexec_file.c | 235 +++++++++++++++++++++
 9 files changed, 560 insertions(+), 13 deletions(-)
 create mode 100644 arch/loongarch/include/asm/image.h
 create mode 100644 arch/loongarch/kernel/kexec_efi.c
 create mode 100644 arch/loongarch/kernel/kexec_elf.c
 create mode 100644 arch/loongarch/kernel/machine_kexec_file.c

-- 
2.43.0