Re: [PATCH v5 bpf-next 5/5] selftests/bpf: add get_stackid_cannot_attach

[Alexei Starovoitov]

On Thu, Jul 23, 2020 at 11:06:48AM -0700, Song Liu wrote:
> + pmu_fd = syscall(__NR_perf_event_open, , -1 /* pid */,
> +  0 /* cpu 0 */, -1 /* group id */,
> +  0 /* flags */);
> + if (pmu_fd < 0 && errno == ENOENT) {
> + printf("%s:SKIP:cannot open PERF_COUNT_HW_CPU_CYCLES with 
> precise_ip > 0\n",
> +__func__);
> + test__skip();
> + goto cleanup;
> + }

That wasn't enough in my test VM.
I've changed it to be: (errno == ENOENT || errno == EOPNOTSUPP)
and applied the set.
Thanks

[PATCH v5 bpf-next 5/5] selftests/bpf: add get_stackid_cannot_attach

[Song Liu]

This test confirms that BPF program that calls bpf_get_stackid() cannot
attach to perf_event with precise_ip > 0 but not PERF_SAMPLE_CALLCHAIN;
and cannot attach if the perf_event has exclude_callchain_kernel.

Signed-off-by: Song Liu 
---
 .../prog_tests/get_stackid_cannot_attach.c| 91 +++
 1 file changed, 91 insertions(+)
 create mode 100644 
tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c

diff --git a/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c 
b/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c
new file mode 100644
index 0..f13149d279bc9
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/get_stackid_cannot_attach.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2020 Facebook
+#include 
+#include "test_stacktrace_build_id.skel.h"
+
+void test_get_stackid_cannot_attach(void)
+{
+   struct perf_event_attr attr = {
+   /* .type = PERF_TYPE_SOFTWARE, */
+   .type = PERF_TYPE_HARDWARE,
+   .config = PERF_COUNT_HW_CPU_CYCLES,
+   .precise_ip = 1,
+   .sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_BRANCH_STACK,
+   .branch_sample_type = PERF_SAMPLE_BRANCH_USER |
+   PERF_SAMPLE_BRANCH_NO_FLAGS |
+   PERF_SAMPLE_BRANCH_NO_CYCLES |
+   PERF_SAMPLE_BRANCH_CALL_STACK,
+   .sample_period = 5000,
+   .size = sizeof(struct perf_event_attr),
+   };
+   struct test_stacktrace_build_id *skel;
+   __u32 duration = 0;
+   int pmu_fd, err;
+
+   skel = test_stacktrace_build_id__open();
+   if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
+   return;
+
+   /* override program type */
+   bpf_program__set_perf_event(skel->progs.oncpu);
+
+   err = test_stacktrace_build_id__load(skel);
+   if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
+   goto cleanup;
+
+   pmu_fd = syscall(__NR_perf_event_open, , -1 /* pid */,
+0 /* cpu 0 */, -1 /* group id */,
+0 /* flags */);
+   if (pmu_fd < 0 && errno == ENOENT) {
+   printf("%s:SKIP:cannot open PERF_COUNT_HW_CPU_CYCLES with 
precise_ip > 0\n",
+  __func__);
+   test__skip();
+   goto cleanup;
+   }
+   if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+ pmu_fd, errno))
+   goto cleanup;
+
+   skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+  pmu_fd);
+   CHECK(!IS_ERR(skel->links.oncpu), "attach_perf_event_no_callchain",
+ "should have failed\n");
+   close(pmu_fd);
+
+   /* add PERF_SAMPLE_CALLCHAIN, attach should succeed */
+   attr.sample_type |= PERF_SAMPLE_CALLCHAIN;
+
+   pmu_fd = syscall(__NR_perf_event_open, , -1 /* pid */,
+0 /* cpu 0 */, -1 /* group id */,
+0 /* flags */);
+
+   if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+ pmu_fd, errno))
+   goto cleanup;
+
+   skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+  pmu_fd);
+   CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event_callchain",
+ "err: %ld\n", PTR_ERR(skel->links.oncpu));
+   close(pmu_fd);
+
+   /* add exclude_callchain_kernel, attach should fail */
+   attr.exclude_callchain_kernel = 1;
+
+   pmu_fd = syscall(__NR_perf_event_open, , -1 /* pid */,
+0 /* cpu 0 */, -1 /* group id */,
+0 /* flags */);
+
+   if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
+ pmu_fd, errno))
+   goto cleanup;
+
+   skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
+  pmu_fd);
+   CHECK(!IS_ERR(skel->links.oncpu), 
"attach_perf_event_exclude_callchain_kernel",
+ "should have failed\n");
+   close(pmu_fd);
+
+cleanup:
+   test_stacktrace_build_id__destroy(skel);
+}
-- 
2.24.1