From 198034a87dfeb64d5a8359a5089022c6b923646e Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 21 May 2024 09:34:01 -0700 Subject: [PATCH] selftests/bpf: extend multi-uprobe tests with USDTs Validate libbpf's USDT-over-multi-uprobe logic by adding USDTs to existing multi-uprobe tests. This checks correct libbpf fallback to singular uprobes (when run on older kernels with buggy PID filtering). We reuse already established child process and child thread testing infrastructure, so additions are minimal. These test fail on either older kernels or older version of libbpf that doesn't detect PID filtering problems. Acked-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240521163401.3005045-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- .../bpf/prog_tests/uprobe_multi_test.c | 25 ++++++++++++++ .../selftests/bpf/progs/uprobe_multi.c | 33 +++++++++++++++++-- 2 files changed, 56 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c index 677232d314322b..bf6ca8e3eb1314 100644 --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c @@ -8,6 +8,7 @@ #include "uprobe_multi_usdt.skel.h" #include "bpf/libbpf_internal.h" #include "testing_helpers.h" +#include "../sdt.h" static char test_data[] = "test_data"; @@ -26,6 +27,11 @@ noinline void uprobe_multi_func_3(void) asm volatile (""); } +noinline void usdt_trigger(void) +{ + STAP_PROBE(test, pid_filter_usdt); +} + struct child { int go[2]; int c2p[2]; /* child -> parent channel */ @@ -90,6 +96,7 @@ static struct child *spawn_child(void) uprobe_multi_func_1(); uprobe_multi_func_2(); uprobe_multi_func_3(); + usdt_trigger(); exit(errno); } @@ -117,6 +124,7 @@ static void *child_thread(void *ctx) uprobe_multi_func_1(); uprobe_multi_func_2(); uprobe_multi_func_3(); + usdt_trigger(); err = 0; pthread_exit(&err); @@ -182,6 +190,7 @@ static void uprobe_multi_test_run(struct uprobe_multi *skel, struct child *child uprobe_multi_func_1(); uprobe_multi_func_2(); uprobe_multi_func_3(); + usdt_trigger(); } if (child) @@ -269,8 +278,24 @@ __test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_mul if (!ASSERT_OK_PTR(skel->links.uprobe_extra, "bpf_program__attach_uprobe_multi")) goto cleanup; + /* Attach (uprobe-backed) USDTs */ + skel->links.usdt_pid = bpf_program__attach_usdt(skel->progs.usdt_pid, pid, binary, + "test", "pid_filter_usdt", NULL); + if (!ASSERT_OK_PTR(skel->links.usdt_pid, "attach_usdt_pid")) + goto cleanup; + + skel->links.usdt_extra = bpf_program__attach_usdt(skel->progs.usdt_extra, -1, binary, + "test", "pid_filter_usdt", NULL); + if (!ASSERT_OK_PTR(skel->links.usdt_extra, "attach_usdt_extra")) + goto cleanup; + uprobe_multi_test_run(skel, child); + ASSERT_FALSE(skel->bss->bad_pid_seen_usdt, "bad_pid_seen_usdt"); + if (child) { + ASSERT_EQ(skel->bss->child_pid_usdt, child->pid, "usdt_multi_child_pid"); + ASSERT_EQ(skel->bss->child_tid_usdt, child->tid, "usdt_multi_child_tid"); + } cleanup: uprobe_multi__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi.c b/tools/testing/selftests/bpf/progs/uprobe_multi.c index 86a7ff5d3726d0..44190efcdba217 100644 --- a/tools/testing/selftests/bpf/progs/uprobe_multi.c +++ b/tools/testing/selftests/bpf/progs/uprobe_multi.c @@ -1,8 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 -#include +#include "vmlinux.h" #include #include -#include +#include char _license[] SEC("license") = "GPL"; @@ -23,9 +23,12 @@ __u64 uprobe_multi_sleep_result = 0; int pid = 0; int child_pid = 0; int child_tid = 0; +int child_pid_usdt = 0; +int child_tid_usdt = 0; int expect_pid = 0; bool bad_pid_seen = false; +bool bad_pid_seen_usdt = false; bool test_cookie = false; void *user_ptr = 0; @@ -112,3 +115,29 @@ int uprobe_extra(struct pt_regs *ctx) /* we need this one just to mix PID-filtered and global uprobes */ return 0; } + +SEC("usdt") +int usdt_pid(struct pt_regs *ctx) +{ + __u64 cur_pid_tgid = bpf_get_current_pid_tgid(); + __u32 cur_pid; + + cur_pid = cur_pid_tgid >> 32; + if (pid && cur_pid != pid) + return 0; + + if (expect_pid && cur_pid != expect_pid) + bad_pid_seen_usdt = true; + + child_pid_usdt = cur_pid_tgid >> 32; + child_tid_usdt = (__u32)cur_pid_tgid; + + return 0; +} + +SEC("usdt") +int usdt_extra(struct pt_regs *ctx) +{ + /* we need this one just to mix PID-filtered and global USDT probes */ + return 0; +}