From 4bd11e08e0bb1862fe72495014e33795e412bffb Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Sun, 15 Aug 2021 00:06:09 -0700 Subject: [PATCH] selftests/bpf: Add ref_ctr_offset selftests 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 Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210815070609.987780-17-andrii@kernel.org --- .../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 e40b41c..bf307bb 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 #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 381dafc..e7a19b0 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 3d9435b..d907b44 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 -- 2.7.4