libbpf: Make optimized uprobes backward compatible

[kernel-patches-daemon-bpf]

Pull request for series with
subject: libbpf: Make optimized uprobes backward compatible
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1053028

[kernel-patches-daemon-bpf]

Upstream branch: dc855b7
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1053028
version: 1

[kernel-patches-review-bot]

commit 09ff7cdd01d6d9f807baf814ff8fe1f9ece148de
Author: Jiri Olsa <jolsa@kernel.org>

selftests/bpf: Add test for checking correct nop of optimized usdt

This commit adds a selftest that verifies USDT probe optimization behavior
for the nop,nop5 instruction combo on x86_64. It tests two scenarios: a
single nop probe (usdt_1) that stays on the nop instruction, and a nop,nop5
combo probe (usdt_2) that gets optimized onto nop5.

> diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c
> --- a/tools/testing/selftests/bpf/prog_tests/usdt.c
> +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c

[ ... ]

> +static void subtest_optimized_attach(void)
> +{
> +	struct test_usdt *skel;
> +	__u8 *addr_1, *addr_2;
> +
> +	/* usdt_1 USDT probe has single nop instruction */
> +	addr_1 = find_instr(usdt_1, nop1_nop5_combo, 6);
> +	if (!ASSERT_NULL(addr_1, "usdt_1_find_nop1_nop5_combo"))
> +		return;
> +
> +	addr_1 = find_instr(usdt_1, nop1, 1);
> +	if (!ASSERT_OK_PTR(addr_1, "usdt_1_find_nop1"))
> +		return;
> +
> +	/* usdt_1 USDT probe has nop,nop5 instructions combo */
> +	addr_2 = find_instr(usdt_2, nop1_nop5_combo, 6);

This comment says "usdt_1" but the code operates on "usdt_2". Should this
say "usdt_2 USDT probe has nop,nop5 instructions combo" to match the code?

---

AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

In-Reply-To-Subject: selftests/bpf: Add test for checking correct nop of optimized usdt
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21898612624

AI-authorship-score: low
AI-authorship-explanation: The code follows standard kernel selftest patterns with natural commit message style, and the copy-paste comment error is a characteristically human mistake.
issues-found: 1
issue-severity-score: low
issue-severity-explanation: Comment/code mismatch in test file where comment says usdt_1 but code operates on usdt_2; does not affect test functionality.

[kernel-patches-daemon-bpf]

Forwarding comment 3883176134 via email
In-Reply-To: 20260211084858.750950-5-jolsa@kernel.org
Patch: https://patchwork.kernel.org/project/netdevbpf/patch/20260211084858.750950-5-jolsa@kernel.org/

[kernel-patches-daemon-bpf]

Upstream branch: 4475cda
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=1053028
version: 1

[kernel-patches-daemon-bpf]

At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1053028 expired. Closing PR.