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Tue, 07 Apr 2026 05:59:24 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Tue, 7 Apr 2026 14:59:23 +0200 To: Andrey Grodzovsky Cc: bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, ihor.solodrai@linux.dev, emil@etsalapatis.com, linux-open-source@crowdstrike.com Subject: Re: [RFC PATCH bpf-next v5 2/2] selftests/bpf: Add tests for duplicate kprobe symbol handling Message-ID: References: <20260406193158.754498-1-andrey.grodzovsky@crowdstrike.com> <20260406193158.754498-3-andrey.grodzovsky@crowdstrike.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260406193158.754498-3-andrey.grodzovsky@crowdstrike.com> On Mon, Apr 06, 2026 at 03:31:58PM -0400, Andrey Grodzovsky wrote: SNIP > +static void test_attach_probe_dup_sym(enum probe_attach_mode attach_mode) > +{ > + DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, kprobe_opts); > + struct bpf_link *kprobe_link, *kretprobe_link; > + struct test_attach_probe_manual *skel; > + int err; > + > + /* Load module with duplicate symbol */ > + err = load_module("bpf_testmod_dup_sym.ko", false); > + if (!ASSERT_OK(err, "load_bpf_testmod_dup_sym")) { > + test__skip(); > + return; > + } > + > + skel = test_attach_probe_manual__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel_dup_sym_open_and_load")) > + goto unload_module; > + > + /* manual-attach kprobe/kretprobe with duplicate symbol present */ > + kprobe_opts.attach_mode = attach_mode; > + kprobe_opts.retprobe = false; > + kprobe_link = bpf_program__attach_kprobe_opts(skel->progs.handle_kprobe, > + SYS_NANOSLEEP_KPROBE_NAME, > + &kprobe_opts); > + if (!ASSERT_OK_PTR(kprobe_link, "attach_kprobe_dup_sym")) > + goto cleanup; > + skel->links.handle_kprobe = kprobe_link; > + > + kprobe_opts.retprobe = true; > + kretprobe_link = bpf_program__attach_kprobe_opts(skel->progs.handle_kretprobe, > + SYS_NANOSLEEP_KPROBE_NAME, > + &kprobe_opts); maybe add tests for attaching the shadow module function as well? > diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_dup_sym.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_dup_sym.c > new file mode 100644 > index 000000000000..0e12f68afe3a > --- /dev/null > +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_dup_sym.c > @@ -0,0 +1,48 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2025 CrowdStrike */ > +/* Test module for duplicate kprobe symbol handling */ > +#include > +#include > +#include > + > +/* Duplicate symbol to test kprobe attachment with duplicate symbols. > + * This creates a duplicate of the syscall wrapper used in attach_probe tests. > + * The libbpf fix should handle this by preferring the vmlinux symbol. > + * This function should NEVER be called - kprobes should attach to vmlinux version. > + */ > +#ifdef __x86_64__ > +int __x64_sys_nanosleep(void); > +noinline int __x64_sys_nanosleep(void) > +#elif defined(__s390x__) > +int __s390x_sys_nanosleep(void); > +noinline int __s390x_sys_nanosleep(void) > +#elif defined(__aarch64__) > +int __arm64_sys_nanosleep(void); > +noinline int __arm64_sys_nanosleep(void) > +#elif defined(__riscv) > +int __riscv_sys_nanosleep(void); > +noinline int __riscv_sys_nanosleep(void) > +#else > +int sys_nanosleep(void); > +noinline int sys_nanosleep(void) > +#endif could we use module_fentry_shadow instead? it's in kernel and in bpf_testmod for fentry shadowing test.. it's not executed via test_run but it could be added or we just don't run it jirka > +{ > + WARN_ONCE(1, "bpf_testmod_dup_sym: dummy nanosleep symbol called - this should never execute!\n"); > + return -EINVAL; > +} > + > +static int __init bpf_testmod_dup_sym_init(void) > +{ > + return 0; > +} > + > +static void __exit bpf_testmod_dup_sym_exit(void) > +{ > +} > + > +module_init(bpf_testmod_dup_sym_init); > +module_exit(bpf_testmod_dup_sym_exit); > + > +MODULE_AUTHOR("Andrey Grodzovsky"); > +MODULE_DESCRIPTION("BPF selftest duplicate symbol module"); > +MODULE_LICENSE("GPL"); > -- > 2.34.1 >