[PATCHv4 bpf-next 6/7] selftests/bpf: Add uretprobe compat test

[Jiri Olsa <jolsa@kernel.org>]

Adding test that adds return uprobe inside 32-bit task
and verify the return uprobe and attached bpf programs
get properly executed.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/.gitignore        |  1 +
 tools/testing/selftests/bpf/Makefile          |  7 ++-
 .../selftests/bpf/prog_tests/uprobe_syscall.c | 60 +++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index f1aebabfb017..69d71223c0dd 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -45,6 +45,7 @@ test_cpp
 /veristat
 /sign-file
 /uprobe_multi
+/uprobe_compat
 *.ko
 *.tmp
 xskxceiver
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 82247aeef857..a94352162290 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -133,7 +133,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
 	xskxceiver xdp_redirect_multi xdp_synproxy veristat xdp_hw_metadata \
 	xdp_features bpf_test_no_cfi.ko
 
-TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi
+TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi uprobe_compat
 
 ifneq ($(V),1)
 submake_extras := feature_display=0
@@ -631,6 +631,7 @@ TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\
 		       $(OUTPUT)/xdp_synproxy				\
 		       $(OUTPUT)/sign-file				\
 		       $(OUTPUT)/uprobe_multi				\
+		       $(OUTPUT)/uprobe_compat				\
 		       ima_setup.sh 					\
 		       verify_sig_setup.sh				\
 		       $(wildcard progs/btf_dump_test_case_*.c)		\
@@ -752,6 +753,10 @@ $(OUTPUT)/uprobe_multi: uprobe_multi.c
 	$(call msg,BINARY,,$@)
 	$(Q)$(CC) $(CFLAGS) -O0 $(LDFLAGS) $^ $(LDLIBS) -o $@
 
+$(OUTPUT)/uprobe_compat:
+	$(call msg,BINARY,,$@)
+	$(Q)echo "int main() { return 0; }" | $(CC) $(CFLAGS) -xc -m32 -O0 - -o $@
+
 EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)			\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\
 	feature bpftool							\
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
index c6fdb8c59ea3..bfea9a0368a4 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
@@ -5,6 +5,7 @@
 #ifdef __x86_64__
 
 #include <unistd.h>
+#include <stdlib.h>
 #include <asm/ptrace.h>
 #include <linux/compiler.h>
 #include <linux/stringify.h>
@@ -297,6 +298,58 @@ static void test_uretprobe_syscall_call(void)
 	close(go[1]);
 	close(go[0]);
 }
+
+static void test_uretprobe_compat(void)
+{
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
+		.retprobe = true,
+	);
+	struct uprobe_syscall_executed *skel;
+	int err, go[2], pid, c, status;
+
+	if (pipe(go))
+		return;
+
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		goto cleanup;
+
+	pid = fork();
+	if (pid < 0)
+		goto cleanup;
+
+	/* child */
+	if (pid == 0) {
+		close(go[1]);
+
+		/* wait for parent's kick */
+		err = read(go[0], &c, 1);
+		if (err != 1)
+			exit(-1);
+		execl("./uprobe_compat", "./uprobe_compat", NULL);
+		exit(-1);
+	}
+
+	skel->links.test = bpf_program__attach_uprobe_multi(skel->progs.test, pid,
+							    "./uprobe_compat", "main", &opts);
+	if (!ASSERT_OK_PTR(skel->links.test, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	/* kick the child */
+	write(go[1], &c, 1);
+	err = waitpid(pid, &status, 0);
+	ASSERT_EQ(err, pid, "waitpid");
+
+	/* verify the child exited normally and the bpf program got executed */
+	ASSERT_EQ(WIFEXITED(status), 1, "WIFEXITED");
+	ASSERT_EQ(WEXITSTATUS(status), 0, "WEXITSTATUS");
+	ASSERT_EQ(skel->bss->executed, 1, "executed");
+
+cleanup:
+	uprobe_syscall_executed__destroy(skel);
+	close(go[0]);
+	close(go[1]);
+}
 #else
 static void test_uretprobe_regs_equal(void)
 {
@@ -312,6 +365,11 @@ static void test_uretprobe_syscall_call(void)
 {
 	test__skip();
 }
+
+static void test_uretprobe_compat(void)
+{
+	test__skip();
+}
 #endif
 
 void test_uprobe_syscall(void)
@@ -322,4 +380,6 @@ void test_uprobe_syscall(void)
 		test_uretprobe_regs_change();
 	if (test__start_subtest("uretprobe_syscall_call"))
 		test_uretprobe_syscall_call();
+	if (test__start_subtest("uretprobe_compat"))
+		test_uretprobe_compat();
 }
-- 
2.44.0