[RFC bpf-next 10/11] selftests/bpf: Add uprobe/usdt optimized test

[Jiri Olsa <jolsa@kernel.org>]

Adding tests for optimized uprobe/usdt probes.

Checking that we get expected trampoline and attached bpf programs
get executed properly.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../bpf/prog_tests/uprobe_optimized.c         | 192 ++++++++++++++++++
 .../selftests/bpf/progs/uprobe_optimized.c    |  29 +++
 2 files changed, 221 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_optimized.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_optimized.c

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_optimized.c b/tools/testing/selftests/bpf/prog_tests/uprobe_optimized.c
new file mode 100644
index 000000000000..f6eb4089b1e2
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_optimized.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+
+#ifdef __x86_64__
+
+#include "sdt.h"
+#include "uprobe_optimized.skel.h"
+
+#define TRAMP "[uprobes-trampoline]"
+
+__naked noinline void uprobe_test(void)
+{
+	asm volatile (".byte 0x0f, 0x1f, 0x44, 0x00, 0x00\n\t"
+		      "ret\n\t");
+}
+
+static int find_uprobes_trampoline(void **start, void **end)
+{
+	char line[128];
+	int ret = -1;
+	FILE *maps;
+
+	maps = fopen("/proc/self/maps", "r");
+	if (!maps) {
+		fprintf(stderr, "cannot open maps\n");
+		return -1;
+	}
+
+	while (fgets(line, sizeof(line), maps)) {
+		int m = -1;
+
+		/* We care only about private r-x mappings. */
+		if (sscanf(line, "%p-%p r-xp %*x %*x:%*x %*u %n", start, end, &m) != 2)
+			continue;
+		if (m < 0)
+			continue;
+		if (!strncmp(&line[m], TRAMP, sizeof(TRAMP)-1)) {
+			ret = 0;
+			break;
+		}
+	}
+
+	fclose(maps);
+	return ret;
+}
+
+static void check_attach(struct uprobe_optimized *skel, void (*trigger)(void))
+{
+	void *tramp_start, *tramp_end;
+	struct __arch_relative_insn {
+		u8 op;
+		s32 raddr;
+	} __packed *call;
+
+	unsigned long delta;
+
+	/* Uprobe gets optimized after first trigger, so let's press twice. */
+	trigger();
+	trigger();
+
+	if (!ASSERT_OK(find_uprobes_trampoline(&tramp_start, &tramp_end), "uprobes_trampoline"))
+		return;
+
+	/* Make sure bpf program got executed.. */
+	ASSERT_EQ(skel->bss->executed, 2, "executed");
+
+	/* .. and check the trampoline is as expected. */
+	call = (struct __arch_relative_insn *) trigger;
+
+	delta = tramp_start > (void *) trigger ?
+		tramp_start - (void *) trigger :
+		(void *) trigger - tramp_start;
+
+	/* and minus call instruction size itself */
+	delta -= 5;
+
+	ASSERT_EQ(call->op, 0xe8, "call");
+	ASSERT_EQ(call->raddr, delta, "delta");
+	ASSERT_EQ(tramp_end - tramp_start, 4096, "size");
+}
+
+static void check_detach(struct uprobe_optimized *skel, void (*trigger)(void))
+{
+	unsigned char nop5[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
+	void *tramp_start, *tramp_end;
+
+	/* [uprobes_trampoline] stays after detach */
+	ASSERT_OK(find_uprobes_trampoline(&tramp_start, &tramp_end), "uprobes_trampoline");
+	ASSERT_OK(memcmp(trigger, nop5, 5), "nop5");
+}
+
+static void check(struct uprobe_optimized *skel, struct bpf_link *link,
+		  void (*trigger)(void))
+{
+	check_attach(skel, trigger);
+	bpf_link__destroy(link);
+	check_detach(skel, uprobe_test);
+}
+
+static void test_uprobe(void)
+{
+	struct uprobe_optimized *skel;
+	unsigned long offset;
+
+	skel = uprobe_optimized__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_optimized__open_and_load"))
+		return;
+
+	offset = get_uprobe_offset(&uprobe_test);
+	if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+		goto cleanup;
+
+	skel->links.test_1 = bpf_program__attach_uprobe_opts(skel->progs.test_1,
+					0, "/proc/self/exe", offset, NULL);
+	if (!ASSERT_OK_PTR(skel->links.test_1, "bpf_program__attach_uprobe_opts"))
+		goto cleanup;
+
+	check(skel, skel->links.test_1, uprobe_test);
+	skel->links.test_1 = NULL;
+
+cleanup:
+	uprobe_optimized__destroy(skel);
+}
+
+static void test_uprobe_multi(void)
+{
+	struct uprobe_optimized *skel;
+
+	skel = uprobe_optimized__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_optimized__open_and_load"))
+		return;
+
+	skel->links.test_2 = bpf_program__attach_uprobe_multi(skel->progs.test_2,
+						0, "/proc/self/exe", "uprobe_test", NULL);
+	if (!ASSERT_OK_PTR(skel->links.test_2, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	check(skel, skel->links.test_2, uprobe_test);
+	skel->links.test_2 = NULL;
+
+cleanup:
+	uprobe_optimized__destroy(skel);
+}
+
+__naked noinline void usdt_test(void)
+{
+	STAP_PROBE(optimized_uprobe, usdt);
+	asm volatile ("ret\n");
+}
+
+static void test_usdt(void)
+{
+	struct uprobe_optimized *skel;
+
+	skel = uprobe_optimized__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_optimized__open_and_load"))
+		return;
+
+	skel->links.test_3 = bpf_program__attach_usdt(skel->progs.test_3,
+						-1 /* all PIDs */, "/proc/self/exe",
+						"optimized_uprobe", "usdt", NULL);
+	if (!ASSERT_OK_PTR(skel->links.test_3, "bpf_program__attach_usdt"))
+		goto cleanup;
+
+	check(skel, skel->links.test_3, usdt_test);
+	skel->links.test_3 = NULL;
+
+cleanup:
+	uprobe_optimized__destroy(skel);
+}
+
+static void test_optimized(void)
+{
+	if (test__start_subtest("uprobe"))
+		test_uprobe();
+	if (test__start_subtest("uprobe_multi"))
+		test_uprobe_multi();
+	if (test__start_subtest("usdt"))
+		test_usdt();
+}
+#else
+static void test_optimized(void)
+{
+	test__skip();
+}
+#endif /* __x86_64__ */
+
+void test_uprobe_optimized(void)
+{
+	test_optimized();
+}
diff --git a/tools/testing/selftests/bpf/progs/uprobe_optimized.c b/tools/testing/selftests/bpf/progs/uprobe_optimized.c
new file mode 100644
index 000000000000..7f29c968b7c4
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_optimized.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/usdt.bpf.h>
+
+char _license[] SEC("license") = "GPL";
+int executed = 0;
+
+SEC("uprobe")
+int BPF_UPROBE(test_1)
+{
+	executed++;
+	return 0;
+}
+
+SEC("uprobe.multi")
+int BPF_UPROBE(test_2)
+{
+	executed++;
+	return 0;
+}
+
+SEC("usdt")
+int test_3(struct pt_regs *ctx)
+{
+	executed++;
+	return 0;
+}
-- 
2.47.0