linux-kernel - Re: [PATCH bpf-next v4 8/9] selftests/bpf: add testcases for tracing session

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Message-Id: <e2567121e26195cb0dc4d9285f7269c377a4fb26c0aede0ad8ec112d7a2c98f0@mail.kernel.org>
Date: Wed, 17 Dec 2025 10:24:46 +0000 (UTC)
From: bot+bpf-ci@...nel.org
To: menglong8.dong@...il.com,ast@...nel.org,andrii@...nel.org
Cc: davem@...emloft.net,dsahern@...nel.org,daniel@...earbox.net,martin.lau@...ux.dev,eddyz87@...il.com,song@...nel.org,yonghong.song@...ux.dev,john.fastabend@...il.com,kpsingh@...nel.org,sdf@...ichev.me,haoluo@...gle.com,jolsa@...nel.org,tglx@...utronix.de,mingo@...hat.com,bp@...en8.de,dave.hansen@...ux.intel.com,x86@...nel.org,hpa@...or.com,netdev@...r.kernel.org,bpf@...r.kernel.org,linux-kernel@...r.kernel.org,ast@...nel.org,andrii@...nel.org,daniel@...earbox.net,martin.lau@...nel.org,eddyz87@...il.com,yonghong.song@...ux.dev,clm@...a.com,ihor.solodrai@...ux.dev
Subject: Re: [PATCH bpf-next v4 8/9] selftests/bpf: add testcases for tracing session

> diff --git a/tools/testing/selftests/bpf/progs/fsession_test.c b/tools/testing/selftests/bpf/progs/fsession_test.c
> new file mode 100644
> index 000000000000..f7c96ef1c7a9
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/fsession_test.c
> @@ -0,0 +1,192 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2025 ChinaTelecom */
> +#include <vmlinux.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";

[ ... ]

> +__u64 test8_entry_result = 0;
> +__u64 test8_exit_result = 0;
> +SEC("fsession/bpf_fentry_test1")
> +int BPF_PROG(test8, int a)
> +{
> +	__u64 addr = bpf_get_func_ip(ctx);
> +
> +	if (bpf_fsession_is_return(ctx))
> +		test8_exit_result = (const void *) addr == &bpf_fentry_test1;
> +	else
> +		test8_entry_result = (const void *) addr == &bpf_fentry_test1;
> +	return 0;
> +}

In test8, the code uses &bpf_fentry_test1 without declaring it. Looking at
similar tests like kprobe_multi.c and kprobe_multi_session.c, they include:

    extern const void bpf_fentry_test1 __ksym;

at the top of the file before taking the address of kernel symbols.
Without the __ksym declaration, does the comparison work correctly, or
would this cause the test to fail during compilation or at runtime?


---
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

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/20299185010