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perf test bpf: Hook on epoll_pwait() 

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>
This commit is contained in:
Arnaldo Carvalho de Melo 2018-01-04 12:43:32 -03:00
parent 13cb2d0f51
commit e0337f4f9a
2 changed files with 6 additions and 6 deletions
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4
tools/perf/tests/bpf-script-example.c
View File

@ -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);

8
tools/perf/tests/bpf.c
View File

@ -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,
},