perf test bpf: Hook on epoll_pwait() (e0337f4f) · Commits · 戴 / test

The 'perf test bpf' was hooking a eBPF program on the SyS_epoll_wait() kernel function, that was what the epoll_wait() glibc function ended up calling, but since at least glibc 2.26, the one that comes with, for instance, Fedora 27, glibc ends up calling SyS_epoll_pwait() when epoll_wait() is used, causing this 'perf test' entry to fail. So switch to using epoll_pwait() and hook the eBPF program to the SyS_epoll_pwait() kernel function to make it work on a wider range of glibc and kernel versions. Tested-by:

Wang Nan <wangnan0@huawei.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Link: https://lkml.kernel.org/n/tip-zynvquy63er8s5mrgsz65pto@git.kernel.org Signed-off-by:

Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/bpf-script-example.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -31,8 +31,8 @@ struct bpf_map_def SEC("maps") flip_table = {
		.max_entries = 1,
		};

		SEC("func=SyS_epoll_wait")
		int bpf_func__SyS_epoll_wait(void *ctx)
		SEC("func=SyS_epoll_pwait")
		int bpf_func__SyS_epoll_pwait(void *ctx)
		{
		int ind =0;
		int *flag = bpf_map_lookup_elem(&flip_table, &ind);

tools/perf/tests/bpf.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -19,13 +19,13 @@

		#ifdef HAVE_LIBBPF_SUPPORT

		static int epoll_wait_loop(void)
		static int epoll_pwait_loop(void)
		{
		int i;

		/* Should fail NR_ITERS times */
		for (i = 0; i < NR_ITERS; i++)
		epoll_wait(-(i + 1), NULL, 0, 0);
		epoll_pwait(-(i + 1), NULL, 0, 0, NULL);
		return 0;
		}

		@@ -68,7 +68,7 @@ static struct {
		.name = "[basic_bpf_test]",
		.msg_compile_fail = "fix 'perf test LLVM' first",
		.msg_load_fail = "load bpf object failed",
		.target_func = &epoll_wait_loop,
		.target_func = &epoll_pwait_loop,
		.expect_result = (NR_ITERS + 1) / 2,
		},
		{
		@@ -77,7 +77,7 @@ static struct {
		.name = "[bpf_pinning]",
		.msg_compile_fail = "fix kbuild first",
		.msg_load_fail = "check your vmlinux setting?",
		.target_func = &epoll_wait_loop,
		.target_func = &epoll_pwait_loop,
		.expect_result = (NR_ITERS + 1) / 2,
		.pin = true,
		},

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