Re: [PATCH v5 15/17] crash: Introduce crash_extra_elfcorehdr_size() helper

Extract the elfcorehdr extra space calculation from powerpc into a
generic helper crash_extra_elfcorehdr_size() for use by other
architectures like arm64.

Strengthen the original powerpc check: instead of only checking
the loose CONFIG_CRASH_MAX_MEMORY_RANGES, the new helper enforces
a strict compile-time BUILD_BUG_ON() to guarantee that the absolute
maximum theoretical number of ELF Program Headers will never exceed
the ELF physical limit of PN_XNUM. This ensures absolute safety across
all architectures with zero runtime overhead.

The helper also provides a zero-size stub when crash memory hotplug
is disabled.

Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Dave Young <ruirui.yang@linux.dev>
Cc: Sourabh Jain <redacted>
Signed-off-by: Jinjie Ruan <redacted>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260918100442.3841135-1-ruanjinjie@huawei.com?part=15