Re: [PATCH 15/15] perf test: Remove /usr/bin/cc dependency from Intel PT shell test

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Use of `gettid()` without a fallback wrapper breaks the build on glibc versions older than 2.30.
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commit 98762182c49447a0cdf85565efe77bfa5da71cf6
Author: Ian Rogers <irogers@google.com>

perf test: Remove /usr/bin/cc dependency from Intel PT shell test

This commit replaces runtime C compilation in the test_intel_pt.sh shell test
with built-in workloads (thloop and jitdump) to prevent CI failures due to
missing external C compilers. It also adds multi-architecture compatibility
for the self-modifying code workload.

> diff --git a/tools/perf/tests/workloads/jitdump.c b/tools/perf/tests/workloads/jitdump.c
> new file mode 100644
> index 0000000000000..225d3f3dc6e3b
> --- /dev/null
> +++ b/tools/perf/tests/workloads/jitdump.c

[ ... ]

> +static int write_jitdump(FILE *f, void *addr, const void *dat, size_t sz, uint64_t *idx)
> +{
> +	struct jr_code_load rec = {
> +		.p.id = JIT_CODE_LOAD,
> +		.p.total_size = sizeof(rec) + sz,
> +		.p.timestamp = get_timestamp(),
> +		.pid = getpid(),
> +		.tid = gettid(),

[Severity: Low]
Does this direct call to gettid() break the build on older glibc versions?

Because gettid() was only introduced in glibc 2.30, using it without a
fallback wrapper causes an implicit function declaration error on systems
with older glibc versions. Since the perf tool is compiled with -Werror,
this can result in a hard build failure.

Could this use syscall(__NR_gettid) or provide a local fallback wrapper
similar to how other code in tools/perf/ handles this?

> +		.vma = (unsigned long)addr,
> +		.code_addr = (unsigned long)addr,
> +		.code_size = sz,
> +		.code_index = ++*idx,
> +	};
> +
> +	if (fwrite(&rec, sizeof(rec), 1, f) != 1 || fwrite(dat, sz, 1, f) != 1)
> +		return -1;
> +	return 0;
> +}

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260601000548.1195604-1-irogers@google.com?part=15