Extend attach_probe selftests to specify ref_ctr_offset for uprobe/uretprobe
and validate that its value is incremented from zero.
Turns out that once uprobe is attached with ref_ctr_offset, uretprobe for the
same location/function *has* to use ref_ctr_offset as well, otherwise
perf_event_open() fails with -EINVAL. So this test uses ref_ctr_offset for
both uprobe and uretprobe, even though for the purpose of test uprobe would be
enough.
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/attach_probe.c | 39 +++++++++++++------
tools/testing/selftests/bpf/trace_helpers.c | 21 ++++++++++
tools/testing/selftests/bpf/trace_helpers.h | 1 +
3 files changed, 50 insertions(+), 11 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
index e40b41c44f8b..bf307bb9e446 100644
--- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
+++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
@@ -2,14 +2,18 @@
#include <test_progs.h>
#include "test_attach_probe.skel.h"
+/* this is how USDT semaphore is actually defined, except volatile modifier */
+volatile unsigned short uprobe_ref_ctr __attribute__((unused)) __attribute((section(".probes")));
+
void test_attach_probe(void)
{
+ DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
int duration = 0;
struct bpf_link *kprobe_link, *kretprobe_link;
struct bpf_link *uprobe_link, *uretprobe_link;
struct test_attach_probe* skel;
size_t uprobe_offset;
- ssize_t base_addr;
+ ssize_t base_addr, ref_ctr_offset;
base_addr = get_base_addr();
if (CHECK(base_addr < 0, "get_base_addr",
@@ -17,6 +21,10 @@ void test_attach_probe(void)
return;
uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
+ ref_ctr_offset = get_rel_offset((uintptr_t)&uprobe_ref_ctr);
+ if (!ASSERT_GE(ref_ctr_offset, 0, "ref_ctr_offset"))
+ return;
+
skel = test_attach_probe__open_and_load();
if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
return;
@@ -37,20 +45,28 @@ void test_attach_probe(void)
goto cleanup;
skel->links.handle_kretprobe = kretprobe_link;
- uprobe_link = bpf_program__attach_uprobe(skel->progs.handle_uprobe,
- false /* retprobe */,
- 0 /* self pid */,
- "/proc/self/exe",
- uprobe_offset);
+ ASSERT_EQ(uprobe_ref_ctr, 0, "uprobe_ref_ctr_before");
+
+ uprobe_opts.retprobe = false;
+ uprobe_opts.ref_ctr_offset = ref_ctr_offset;
+ uprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uprobe,
+ 0 /* self pid */,
+ "/proc/self/exe",
+ uprobe_offset,
+ &uprobe_opts);
if (!ASSERT_OK_PTR(uprobe_link, "attach_uprobe"))
goto cleanup;
skel->links.handle_uprobe = uprobe_link;
- uretprobe_link = bpf_program__attach_uprobe(skel->progs.handle_uretprobe,
- true /* retprobe */,
- -1 /* any pid */,
- "/proc/self/exe",
- uprobe_offset);
+ ASSERT_GT(uprobe_ref_ctr, 0, "uprobe_ref_ctr_after");
+
+ /* if uprobe uses ref_ctr, uretprobe has to use ref_ctr as well */
+ uprobe_opts.retprobe = true;
+ uprobe_opts.ref_ctr_offset = ref_ctr_offset;
+ uretprobe_link = bpf_program__attach_uprobe_opts(skel->progs.handle_uretprobe,
+ -1 /* any pid */,
+ "/proc/self/exe",
+ uprobe_offset, &uprobe_opts);
if (!ASSERT_OK_PTR(uretprobe_link, "attach_uretprobe"))
goto cleanup;
skel->links.handle_uretprobe = uretprobe_link;
@@ -77,4 +93,5 @@ void test_attach_probe(void)
cleanup:
test_attach_probe__destroy(skel);
+ ASSERT_EQ(uprobe_ref_ctr, 0, "uprobe_ref_ctr_cleanup");
}
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 381dafce1d8f..e7a19b04d4ea 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -202,3 +202,24 @@ ssize_t get_base_addr(void)
fclose(f);
return -EINVAL;
}
+
+ssize_t get_rel_offset(uintptr_t addr)
+{
+ size_t start, end, offset;
+ char buf[256];
+ FILE *f;
+
+ f = fopen("/proc/self/maps", "r");
+ if (!f)
+ return -errno;
+
+ while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
+ if (addr >= start && addr < end) {
+ fclose(f);
+ return (size_t)addr - start + offset;
+ }
+ }
+
+ fclose(f);
+ return -EINVAL;
+}
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index 3d9435b3dd3b..d907b445524d 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -20,5 +20,6 @@ void read_trace_pipe(void);
ssize_t get_uprobe_offset(const void *addr, ssize_t base);
ssize_t get_base_addr(void);
+ssize_t get_rel_offset(uintptr_t addr);
#endif
--
2.30.2
