Merge branch 'selftests-bpf-add-uprobe-multi-pid-filter-test'

Jiri Olsa says:

====================
selftests/bpf: Add uprobe multi pid filter test

hi,
sending fix for uprobe multi pid filtering together with tests. The first
version included tests for standard uprobes, but as we still do not have
fix for that, sending just uprobe multi changes.

thanks,
jirka

v2 changes:
  - focused on uprobe multi only, removed perf event uprobe specific parts
  - added fix and test for CLONE_VM process filter
---
====================

Link: https://lore.kernel.org/r/20240905115124.1503998-1-jolsa@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

kernel/trace/bpf_trace.c

@@ -3207,7 +3207,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
 	struct bpf_run_ctx *old_run_ctx;
 	int err = 0;
 
-	if (link->task && current->mm != link->task->mm)
+	if (link->task && !same_thread_group(current, link->task))
 		return 0;
 
 	if (sleepable)

tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c

@@ -7,6 +7,7 @@
 #include "uprobe_multi_bench.skel.h"
 #include "uprobe_multi_usdt.skel.h"
 #include "uprobe_multi_consumers.skel.h"
+#include "uprobe_multi_pid_filter.skel.h"
 #include "bpf/libbpf_internal.h"
 #include "testing_helpers.h"
 #include "../sdt.h"
@@ -39,6 +40,7 @@ struct child {
 	int pid;
 	int tid;
 	pthread_t thread;
+	char stack[65536];
 };
 
 static void release_child(struct child *child)
@@ -68,41 +70,54 @@ static void kick_child(struct child *child)
 	fflush(NULL);
 }
 
-static struct child *spawn_child(void)
+static int child_func(void *arg)
 {
-	static struct child child;
-	int err;
-	int c;
+	struct child *child = arg;
+	int err, c;
 
+	close(child->go[1]);
+
+	/* wait for parent's kick */
+	err = read(child->go[0], &c, 1);
+	if (err != 1)
+		exit(err);
+
+	uprobe_multi_func_1();
+	uprobe_multi_func_2();
+	uprobe_multi_func_3();
+	usdt_trigger();
+
+	exit(errno);
+}
+
+static int spawn_child_flag(struct child *child, bool clone_vm)
+{
 	/* pipe to notify child to execute the trigger functions */
-	if (pipe(child.go))
-		return NULL;
+	if (pipe(child->go))
+		return -1;
 
-	child.pid = child.tid = fork();
-	if (child.pid < 0) {
-		release_child(&child);
+	if (clone_vm) {
+		child->pid = child->tid = clone(child_func, child->stack + sizeof(child->stack)/2,
+						CLONE_VM|SIGCHLD, child);
+	} else {
+		child->pid = child->tid = fork();
+	}
+	if (child->pid < 0) {
+		release_child(child);
 		errno = EINVAL;
-		return NULL;
+		return -1;
 	}
 
-	/* child */
-	if (child.pid == 0) {
-		close(child.go[1]);
+	/* fork-ed child */
+	if (!clone_vm && child->pid == 0)
+		child_func(child);
 
-		/* wait for parent's kick */
-		err = read(child.go[0], &c, 1);
-		if (err != 1)
-			exit(err);
+	return 0;
+}
 
-		uprobe_multi_func_1();
-		uprobe_multi_func_2();
-		uprobe_multi_func_3();
-		usdt_trigger();
-
-		exit(errno);
-	}
-
-	return &child;
+static int spawn_child(struct child *child)
+{
+	return spawn_child_flag(child, false);
 }
 
 static void *child_thread(void *ctx)
@@ -131,39 +146,38 @@ static void *child_thread(void *ctx)
 	pthread_exit(&err);
 }
 
-static struct child *spawn_thread(void)
+static int spawn_thread(struct child *child)
 {
-	static struct child child;
 	int c, err;
 
 	/* pipe to notify child to execute the trigger functions */
-	if (pipe(child.go))
-		return NULL;
+	if (pipe(child->go))
+		return -1;
 	/* pipe to notify parent that child thread is ready */
-	if (pipe(child.c2p)) {
-		close(child.go[0]);
-		close(child.go[1]);
-		return NULL;
+	if (pipe(child->c2p)) {
+		close(child->go[0]);
+		close(child->go[1]);
+		return -1;
 	}
 
-	child.pid = getpid();
+	child->pid = getpid();
 
-	err = pthread_create(&child.thread, NULL, child_thread, &child);
+	err = pthread_create(&child->thread, NULL, child_thread, child);
 	if (err) {
 		err = -errno;
-		close(child.go[0]);
-		close(child.go[1]);
-		close(child.c2p[0]);
-		close(child.c2p[1]);
+		close(child->go[0]);
+		close(child->go[1]);
+		close(child->c2p[0]);
+		close(child->c2p[1]);
 		errno = -err;
-		return NULL;
+		return -1;
 	}
 
-	err = read(child.c2p[0], &c, 1);
+	err = read(child->c2p[0], &c, 1);
 	if (!ASSERT_EQ(err, 1, "child_thread_ready"))
-		return NULL;
+		return -1;
 
-	return &child;
+	return 0;
 }
 
 static void uprobe_multi_test_run(struct uprobe_multi *skel, struct child *child)
@@ -304,24 +318,22 @@ __test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_mul
 static void
 test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_multi_opts *opts)
 {
-	struct child *child;
+	static struct child child;
 
 	/* no pid filter */
 	__test_attach_api(binary, pattern, opts, NULL);
 
 	/* pid filter */
-	child = spawn_child();
-	if (!ASSERT_OK_PTR(child, "spawn_child"))
+	if (!ASSERT_OK(spawn_child(&child), "spawn_child"))
 		return;
 
-	__test_attach_api(binary, pattern, opts, child);
+	__test_attach_api(binary, pattern, opts, &child);
 
 	/* pid filter (thread) */
-	child = spawn_thread();
-	if (!ASSERT_OK_PTR(child, "spawn_thread"))
+	if (!ASSERT_OK(spawn_thread(&child), "spawn_thread"))
 		return;
 
-	__test_attach_api(binary, pattern, opts, child);
+	__test_attach_api(binary, pattern, opts, &child);
 }
 
 static void test_attach_api_pattern(void)
@@ -712,24 +724,22 @@ static void __test_link_api(struct child *child)
 
 static void test_link_api(void)
 {
-	struct child *child;
+	static struct child child;
 
 	/* no pid filter */
 	__test_link_api(NULL);
 
 	/* pid filter */
-	child = spawn_child();
-	if (!ASSERT_OK_PTR(child, "spawn_child"))
+	if (!ASSERT_OK(spawn_child(&child), "spawn_child"))
 		return;
 
-	__test_link_api(child);
+	__test_link_api(&child);
 
 	/* pid filter (thread) */
-	child = spawn_thread();
-	if (!ASSERT_OK_PTR(child, "spawn_thread"))
+	if (!ASSERT_OK(spawn_thread(&child), "spawn_thread"))
 		return;
 
-	__test_link_api(child);
+	__test_link_api(&child);
 }
 
 static struct bpf_program *
@@ -942,6 +952,70 @@ static void test_consumers(void)
 	uprobe_multi_consumers__destroy(skel);
 }
 
+static struct bpf_program *uprobe_multi_program(struct uprobe_multi_pid_filter *skel, int idx)
+{
+	switch (idx) {
+	case 0: return skel->progs.uprobe_multi_0;
+	case 1: return skel->progs.uprobe_multi_1;
+	case 2: return skel->progs.uprobe_multi_2;
+	}
+	return NULL;
+}
+
+#define TASKS 3
+
+static void run_pid_filter(struct uprobe_multi_pid_filter *skel, bool clone_vm, bool retprobe)
+{
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts, .retprobe = retprobe);
+	struct bpf_link *link[TASKS] = {};
+	struct child child[TASKS] = {};
+	int i;
+
+	memset(skel->bss->test, 0, sizeof(skel->bss->test));
+
+	for (i = 0; i < TASKS; i++) {
+		if (!ASSERT_OK(spawn_child_flag(&child[i], clone_vm), "spawn_child"))
+			goto cleanup;
+		skel->bss->pids[i] = child[i].pid;
+	}
+
+	for (i = 0; i < TASKS; i++) {
+		link[i] = bpf_program__attach_uprobe_multi(uprobe_multi_program(skel, i),
+							   child[i].pid, "/proc/self/exe",
+							   "uprobe_multi_func_1", &opts);
+		if (!ASSERT_OK_PTR(link[i], "bpf_program__attach_uprobe_multi"))
+			goto cleanup;
+	}
+
+	for (i = 0; i < TASKS; i++)
+		kick_child(&child[i]);
+
+	for (i = 0; i < TASKS; i++) {
+		ASSERT_EQ(skel->bss->test[i][0], 1, "pid");
+		ASSERT_EQ(skel->bss->test[i][1], 0, "unknown");
+	}
+
+cleanup:
+	for (i = 0; i < TASKS; i++)
+		bpf_link__destroy(link[i]);
+	for (i = 0; i < TASKS; i++)
+		release_child(&child[i]);
+}
+
+static void test_pid_filter_process(bool clone_vm)
+{
+	struct uprobe_multi_pid_filter *skel;
+
+	skel = uprobe_multi_pid_filter__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_multi_pid_filter__open_and_load"))
+		return;
+
+	run_pid_filter(skel, clone_vm, false);
+	run_pid_filter(skel, clone_vm, true);
+
+	uprobe_multi_pid_filter__destroy(skel);
+}
+
 static void test_bench_attach_uprobe(void)
 {
 	long attach_start_ns = 0, attach_end_ns = 0;
@@ -1034,4 +1108,8 @@ void test_uprobe_multi_test(void)
 		test_attach_uprobe_fails();
 	if (test__start_subtest("consumers"))
 		test_consumers();
+	if (test__start_subtest("filter_fork"))
+		test_pid_filter_process(false);
+	if (test__start_subtest("filter_clone_vm"))
+		test_pid_filter_process(true);
 }

tools/testing/selftests/bpf/progs/uprobe_multi_pid_filter.c

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 pids[3];
+__u32 test[3][2];
+
+static void update_pid(int idx)
+{
+	__u32 pid = bpf_get_current_pid_tgid() >> 32;
+
+	if (pid == pids[idx])
+		test[idx][0]++;
+	else
+		test[idx][1]++;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_0(struct pt_regs *ctx)
+{
+	update_pid(0);
+	return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_1(struct pt_regs *ctx)
+{
+	update_pid(1);
+	return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_multi_2(struct pt_regs *ctx)
+{
+	update_pid(2);
+	return 0;
+}