Add kexec_file support for LoongArch

From: Youling Tang <[email protected]>

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:
v4:
* Add the character "kexec_file" to the command-line parameter.
* Fixed the issue where kexec_file failed to load the KASLR kernel startup.
* Modify the member name of the loongarch_image_header structure.
* Modify the patch commit message.

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 (7):
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: Automatically disable kaslr when the kernel loads from
kexec_file
LoongArch: Enable CONFIG_KEXEC_FILE

 arch/loongarch/Kconfig                     |  10 +
 arch/loongarch/configs/loongson3_defconfig |   1 +
 arch/loongarch/include/asm/image.h         |  53 +++++
 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 | 244 +++++++++++++++++++++
 arch/loongarch/kernel/relocate.c           |   4 +
 10 files changed, 569 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