On Wed, Jul 1, 2020 at 11:04 AM Yonghong Song <yhs@xxxxxx> wrote: > > > > On 7/1/20 10:53 AM, Hao Luo wrote: > > The test_vmlinux test uses hrtimer_nanosleep as hook to test tracing > > programs. But in a kernel built by clang, which performs more aggresive > > inlining, that function gets inlined into its caller SyS_nanosleep. > > Therefore, even though fentry and kprobe do hook on the function, > > they aren't triggered by the call to nanosleep in the test. > > > > A possible fix is switching to use a function that is less likely to > > be inlined, such as hrtimer_range_start_ns. The EXPORT_SYMBOL functions > > shouldn't be inlined based on the description of [1], therefore safe > > to use for this test. Also the arguments of this function include the > > duration of sleep, therefore suitable for test verification. > > > > [1] af3b56289be1 time: don't inline EXPORT_SYMBOL functions > > > > Tested: > > In a clang build kernel, before this change, the test fails: > > > > test_vmlinux:PASS:skel_open 0 nsec > > test_vmlinux:PASS:skel_attach 0 nsec > > test_vmlinux:PASS:tp 0 nsec > > test_vmlinux:PASS:raw_tp 0 nsec > > test_vmlinux:PASS:tp_btf 0 nsec > > test_vmlinux:FAIL:kprobe not called > > test_vmlinux:FAIL:fentry not called > > > > After switching to hrtimer_range_start_ns, the test passes: > > > > test_vmlinux:PASS:skel_open 0 nsec > > test_vmlinux:PASS:skel_attach 0 nsec > > test_vmlinux:PASS:tp 0 nsec > > test_vmlinux:PASS:raw_tp 0 nsec > > test_vmlinux:PASS:tp_btf 0 nsec > > test_vmlinux:PASS:kprobe 0 nsec > > test_vmlinux:PASS:fentry 0 nsec > > > > Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx> > > Acked-by: Andrii Nakryiko <andriin@xxxxxx> > > Thanks! > Acked-by: Yonghong Song <yhs@xxxxxx> Applied. Thanks
