[PATCH v3 00/11] kdump: reduce vmcore size and capture time

[Wandun Chen]

From: Wandun Chen <chenwandun at lixiang.com>

On SoCs that carve out large firmware-owned reserved memory (GPU
firmware, DSP, modem, camera ISP, NPU, ...), kdump currently dumps
those carveouts as part of system RAM even though their contents are
firmware state that is not useful for kernel crash analysis.

This series introduces an opt-in 'dumpable' flag [1] on struct
reserved_mem and uses it to filter the elfcorehdr PT_LOAD ranges on
DT-based architectures (arm64, riscv, loongarch). By default reserved
regions are treated as non-dumpable; CMA regions are explicitly opted
in because their pages are returned to the buddy allocator and may
carry key crash-analysis data.

The series is organized as follows:
Patches 1-3: Pre-existing fixes and a small prep change.
Patches 4-5: Restructure to allow appending /memreserve/ entries.
Patches 6-7: Add a dumpable flag and append /memreserve/ entries.
Patch 8: Add generic kdump helpers.
Patches 9-11: Wire the helpers into arm64, riscv and loongarch kdump
              elfcorehdr preparation.

v2 --> v3:
1. Fix out-of-bounds issue if device tree lacks /reserved-memory node.[2]
2. Fix UAF issue when alloc_reserved_mem_array() fails.
3. Add some prepare patches.

v1 --> v2:
1. v1 added an opt-out DT property ('linux,no-dump'). Per Rob's
   feedback [1], v2 drop that property and exclude reserve memory
   by default.
2. Split some prepared patches from the original patches.
3. Address coding-style comments on patch 5 from Rob.

[1] https://lore.kernel.org/lkml/20260506144542.GA2072596-robh@kernel.org/
[2] https://sashiko.dev/#/patchset/20260520091844.592753-1-chenwandun%40lixiang.com?part=4

Wandun Chen (11):
  of: reserved_mem: handle NULL name in of_reserved_mem_lookup()
  kexec/crash: provide crash_exclude_mem_range() stub when
    CONFIG_CRASH_DUMP=n
  of: reserved_mem: avoid post-init UAF when alloc_reserved_mem_array()
    fails
  of: reserved_mem: zero total_reserved_mem_cnt if no valid
    /reserved-memory entry
  of: reserved_mem: split alloc_reserved_mem_array() from
    fdt_scan_reserved_mem_late()
  of: reserved_mem: add dumpable flag to opt-in vmcore
  of: reserved_mem: save /memreserve/ entries into the reserved_mem
    array
  of: reserved_mem: add kdump helpers to exclude non-dumpable regions
  arm64: kdump: exclude non-dumpable reserved memory regions from vmcore
  riscv: kdump: exclude non-dumpable reserved memory regions from vmcore
  loongarch: kdump: exclude non-dumpable reserved memory regions from
    vmcore

 arch/arm64/kernel/machine_kexec_file.c     |   6 ++
 arch/loongarch/kernel/machine_kexec_file.c |   6 ++
 arch/riscv/kernel/machine_kexec_file.c     |   4 +
 drivers/of/fdt.c                           |  11 +-
 drivers/of/of_private.h                    |   3 +
 drivers/of/of_reserved_mem.c               | 117 +++++++++++++++++++--
 include/linux/crash_core.h                 |   6 ++
 include/linux/of_reserved_mem.h            |  15 +++
 kernel/dma/contiguous.c                    |   1 +
 9 files changed, 157 insertions(+), 12 deletions(-)

-- 
2.43.0