[PATCHv5 13/13] selftests/bpf: Add tests for forked/cloned optimized uprobes
From: Jiri Olsa <jolsa@kernel.org>
Date: 2026-07-01 11:16:06
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds
Adding tests for forked/cloned optimized uprobes and make sure the child can properly execute optimized probe for both fork (dups mm) and clone with CLONE_VM. Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- .../selftests/bpf/prog_tests/uprobe_syscall.c | 89 +++++++++++++++++++ 1 file changed, 89 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
index ff07e5df9a65..eb067f029a9f 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c@@ -4,6 +4,8 @@ #ifdef __x86_64__ +#define _GNU_SOURCE +#include <sched.h> #include <unistd.h> #include <asm/ptrace.h> #include <linux/compiler.h>
@@ -13,6 +15,7 @@ #include <sys/syscall.h> #include <sys/prctl.h> #include <asm/prctl.h> +#include <stdnoreturn.h> #include "uprobe_syscall.skel.h" #include "uprobe_syscall_executed.skel.h" #include "bpf/libbpf_internal.h"
@@ -954,6 +957,88 @@ static void test_uprobe_error(void) ASSERT_EQ(errno, EPROTO, "errno"); } +__attribute__((aligned(16))) +__nocf_check __weak __naked void uprobe_fork_test(void) +{ + asm volatile ( + ".byte 0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00\n" /* nop10 */ + "ret\n" + ); +} + +static noreturn int child_func(void *arg) +{ + struct uprobe_syscall_executed *skel = arg; + + /* Make sure the child's probe is still there and optimized.. */ + if (memcmp(uprobe_fork_test, lea_rsp, sizeof(lea_rsp))) + _exit(1); + + skel->bss->pid = getpid(); + + /* .. and it executes properly. */ + uprobe_fork_test(); + + if (skel->bss->executed != 3) + _exit(2); + + _exit(0); +} + +static void test_uprobe_fork_optimized(bool clone_vm) +{ + struct uprobe_syscall_executed *skel = NULL; + struct bpf_link *link = NULL; + unsigned long offset; + int pid, status, err; + char stack[65535]; + + offset = get_uprobe_offset(&uprobe_fork_test); + if (!ASSERT_GE(offset, 0, "get_uprobe_offset")) + return; + + skel = uprobe_syscall_executed__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_and_load")) + goto cleanup; + + link = bpf_program__attach_uprobe_opts(skel->progs.test_uprobe, + -1, "/proc/self/exe", offset, NULL); + if (!ASSERT_OK_PTR(link, "attach_uprobe")) + goto cleanup; + + skel->bss->pid = getpid(); + + /* Trigger optimization of uprobe in uprobe_fork_test. */ + uprobe_fork_test(); + uprobe_fork_test(); + + /* Make sure it got optimied. */ + if (!ASSERT_OK(memcmp(uprobe_fork_test, lea_rsp, sizeof(lea_rsp)), "optimized")) + goto cleanup; + + if (clone_vm) { + pid = clone(child_func, stack + sizeof(stack), CLONE_VM|SIGCHLD, skel); + if (!ASSERT_GT(pid, 0, "clone")) + goto cleanup; + } else { + pid = fork(); + if (!ASSERT_GE(pid, 0, "fork")) + goto cleanup; + if (pid == 0) + child_func(skel); + } + + /* Wait for the child and verify it exited properly with 0. */ + err = waitpid(pid, &status, 0); + if (ASSERT_EQ(err, pid, "waitpid")) { + ASSERT_EQ(WIFEXITED(status), 1, "child_exited"); + ASSERT_EQ(WEXITSTATUS(status), 0, "child_exit_code"); + } + +cleanup: + uprobe_syscall_executed__destroy(skel); +} + static void __test_uprobe_syscall(void) { if (test__start_subtest("uretprobe_regs_equal"))
@@ -974,6 +1059,10 @@ static void __test_uprobe_syscall(void) test_uprobe_race(); if (test__start_subtest("uprobe_red_zone")) test_uprobe_red_zone(); + if (test__start_subtest("uprobe_optimized_fork")) + test_uprobe_fork_optimized(false); + if (test__start_subtest("uprobe_optimized_clone_vm")) + test_uprobe_fork_optimized(true); if (test__start_subtest("uprobe_error")) test_uprobe_error(); if (test__start_subtest("uprobe_regs_equal"))
--
2.54.0