arm64/riscv: Add support for crashkernel CMA reservation

The crash memory allocation, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
This patch set handle them in crash core in a general way, which eliminate
a lot of duplication code.

And add support for crashkernel CMA reservation for arm64 and riscv.

Also add support for arm64 crash hotplug.

This patch set is rebased on v7.1-rc1.

Basic second kernel boot test were performed on QEMU platforms for x86,
ARM64 and RISC-V architectures with the following parameters:

	"cma=256M crashkernel=4G crashkernel=64M,cma"

For first kernel, there will be such log:

	# dmesg | grep crash
	[    0.000000] crashkernel low memory reserved: 0xe8000000 - 0xf0000000 (128 MB)
	[    0.000000] crashkernel reserved: 0x000000023e600000 - 0x000000033e600000 (4096 MB)
	[    0.000000] crashkernel CMA reserved: 64 MB in 1 ranges

	# dmesg | grep cma
	[    0.000000] cma: Reserved 256 MiB at 0x00000000f0000000
	[    0.000000] cma: Reserved 64 MiB at 0x0000000100000000

For second kernel, there will be such log:

	[    0.000000] OF: fdt: Looking for usable-memory-range property...
	[    0.000000] OF: fdt: cap_mem_regions[0]: base=0x000000023e600000, size=0x0000000100000000
	[    0.000000] OF: fdt: cap_mem_regions[1]: base=0x00000000e8000000, size=0x0000000008000000
	[    0.000000] OF: fdt: cap_mem_regions[2]: base=0x0000000100000000, size=0x0000000004000000

Changes in v14:
- Fix image->elf_headers memory leak during retry loop for arm64 as Sashiko
  AI code review pointed out.
- Solve the hotplug notifier arch_crash_handle_hotplug_event() AA
  self-deadlock problem as Sashiko AI code review pointed out.
- Fix the TOCTOU issue in prepare_elf_headers() by get_online_mems().
- -ENOMEM -> -EAGAIN as Breno suggested.
- Add support for arm64 crash hotplug.
- Link to v13: https://lore.kernel.org/all/20260511030454.1730881-1-ruan...

Changes in v13:
- Rebased on v7.1-rc1.
- Update the commit message.
- Add Reviewed-by.
- Link to v12: https://lore.kernel.org/all/20260402072701.628293-1-ruanj...

Changes in v12:
- Remove the unused "nr_mem_ranges" for x86.
- Add "Fix crashk_low_res not exclude bug" test log.
- Provide a separate patch for each architecture for using
  crash_prepare_headers(), which will make the review more convenient.
- Add Reviewed-by and Tested-by.
- Link to v11: https://lore.kernel.org/all/20260328074013.3589544-1-ruan...

Changes in v11:
- Avoid silently drop crash memory if the crash kernel is built without
  CONFIG_CMA.
- Remove unnecessary "cmem->nr_ranges = 0" for arch_crash_populate_cmem()
  as we use kvzalloc().
- Provide a separate patch for each architecture to fix the existing
  buffer overflow issue.
- Add Acked-bys for arm64.

Changes in v10:
- Fix crashk_low_res not excluded bug in the existing
  RISC-V code.
- Fix an existing memory leak issue in the existing PowerPC code.
- Fix the ordering issue of adding CMA ranges to
  "linux,usable-memory-range".
- Fix an existing concurrency issue. A Concurrent memory hotplug may occur
  between reading memblock and attempting to fill cmem during kexec_load()
  for almost all existing architectures.
- Link to v9: https://lore.kernel.org/all/20260323072745.2481719-1-ruan...

Changes in v9:
- Collect Reviewed-by and Acked-by, and prepare for Sashiko AI review.
- Link to v8: https://lore.kernel.org/all/20260302035315.3892241-1-ruan...

Changes in v8:
- Fix the build issues reported by kernel test robot and Sourabh.
- Link to v7: https://lore.kernel.org/all/20260226130437.1867658-1-ruan...

Changes in v7:
- Correct the inclusion of CMA-reserved ranges for kdump kernel in of/kexec
  for arm64 and riscv.
- Add Acked-by.
- Link to v6: https://lore.kernel.org/all/20260224085342.387996-1-ruanj...

Changes in v6:
- Update the crash core exclude code as Mike suggested.
- Rebased on v7.0-rc1.
- Add acked-by.
- Link to v5: https://lore.kernel.org/all/20260212101001.343158-1-ruanj...

Jinjie Ruan (16):
  riscv: kexec_file: Fix crashk_low_res not exclude bug
  powerpc/crash: Fix possible memory leak in update_crash_elfcorehdr()
  arm64: kexec: Fix image->elf_headers memory leak during retry loop
  x86/kexec: Fix potential buffer overflow in prepare_elf_headers()
  arm64: kexec_file: Fix potential buffer overflow in
    prepare_elf_headers()
  riscv: kexec_file: Fix potential buffer overflow in
    prepare_elf_headers()
  LoongArch: kexec: Fix potential buffer overflow in
    prepare_elf_headers()
  crash: Add crash_prepare_headers() to exclude crash kernel memory
  arm64: kexec_file: Use crash_prepare_headers() helper to simplify code
  x86/kexec: Use crash_prepare_headers() helper to simplify code
  riscv: kexec_file: Use crash_prepare_headers() helper to simplify code
  LoongArch: kexec: Use crash_prepare_headers() helper to simplify code
  crash: Use crash_exclude_core_ranges() on powerpc
  arm64: kexec: Add support for crashkernel CMA reservation
  riscv: kexec: Add support for crashkernel CMA reservation
  arm64/crash: Add crash hotplug support

Sourabh Jain (1):
  powerpc/crash: sort crash memory ranges before preparing elfcorehdr

 .../admin-guide/kernel-parameters.txt         |  16 +--
 arch/arm64/Kconfig                            |   3 +
 arch/arm64/include/asm/kexec.h                |  14 +-
 arch/arm64/kernel/Makefile                    |   1 +
 arch/arm64/kernel/crash.c                     | 125 ++++++++++++++++++
 arch/arm64/kernel/kexec_image.c               |  22 ++-
 arch/arm64/kernel/machine_kexec_file.c        |  78 ++++++-----
 arch/arm64/mm/init.c                          |   5 +-
 arch/loongarch/kernel/machine_kexec_file.c    |  43 +++---
 arch/powerpc/include/asm/kexec_ranges.h       |   1 -
 arch/powerpc/kexec/crash.c                    |   7 +-
 arch/powerpc/kexec/ranges.c                   | 101 +-------------
 arch/riscv/kernel/machine_kexec_file.c        |  42 +++---
 arch/riscv/mm/init.c                          |   5 +-
 arch/x86/kernel/crash.c                       |  92 ++-----------
 drivers/of/fdt.c                              |   9 +-
 drivers/of/kexec.c                            |   9 ++
 include/linux/crash_core.h                    |  11 ++
 include/linux/crash_reserve.h                 |   4 +-
 kernel/crash_core.c                           | 102 +++++++++++++-
 20 files changed, 392 insertions(+), 298 deletions(-)
 create mode 100644 arch/arm64/kernel/crash.c

-- 
2.34.1