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authorKees Cook <kees+treewide@kernel.org>2026-09-02 15:31:14 -0700
committerKees Cook <kees@kernel.org>2026-09-04 21:37:00 -0700
commit3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch)
treec65086f9bdcd48c6360fb7cb4598bca084da1f32 /tools/lib/perf/TODO
downloadlinux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz
linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc() family of allocations to kmalloc_obj() via the existing rules in scripts/coccinelle/api/kmalloc_objs.cocci This catches both the set of kmalloc() uses added since the first kmalloc_obj() conversions in v7.0 and adds a large group missed in the first pass due to Coccinelle not interacting well with the cleanup.h scoped_...() family of macros[1]. I worked around this with spatch's "--macro-file" argument to a file with all the scoped_...() macros mapped to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control flow indicator I could find. Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc, riscv, and s390 with no new warnings. Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1] Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2] Signed-off-by: Kees Cook <kees+treewide@kernel.org>
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+Future ABI changes
+==================
+
+This file collects items that require a libperf ABI bump. Each entry
+should describe the current limitation, the desired end state, and the
+scope of the change so that a future ABI revision can batch them
+together.
+
+1. Widen struct perf_cpu.cpu from int16_t to int
+ - Current limit: 32767 CPUs. No architecture exceeds this today
+ (x86_64 max is 8192, arm64 is 4096), but NR_CPUS limits keep
+ growing. perf clamps to INT16_MAX in set_max_cpu_num() as a
+ safety net.
+ - Code simplification: the int16_t forces defensive truncation
+ checks at every boundary where a wider CPU index (int from
+ sample->cpu, al->cpu, etc.) is narrowed into struct perf_cpu.
+ Without these checks, values > 32767 silently wrap to negative
+ numbers (two's complement), bypassing bounds validation.
+ Widening to int eliminates this entire class of silent
+ truncation bugs and removes the need for the INT16_MAX clamp
+ in set_max_cpu_num().
+ - Scope: struct perf_cpu is embedded everywhere — perf_cpu_map__cpu(),
+ perf_cpu_map__min(), perf_cpu_map__max(), perf_cpu_map__has(), the
+ for_each_cpu macros, and all internal callers. The perf_cpu_map
+ internal array (RC_CHK_ACCESS(map)->map[]) stores struct perf_cpu
+ directly. Widening changes the struct layout and every function
+ that returns or accepts struct perf_cpu by value.
+ - Migration: bump LIBPERF version in libperf.map, audit all
+ sizeof(struct perf_cpu) assumptions, update perf.data
+ serialization if needed.