selftests/bpf: Uprobe tests should verify param/return values

uprobe/uretprobe tests don't do any validation of arguments/return values,
and without this we can't be sure we are attached to the right function,
or that we are indeed attached to a uprobe or uretprobe.  To fix this
record argument and return value for auto-attached functions and ensure
these match expectations.  Also need to filter by pid to ensure we do
not pick up stray malloc()s since auto-attach traces libc system-wide.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649245431-29956-4-git-send-email-alan.maguire@oracle.com

1 files changed, 18 insertions, 7 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c b/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c
index 03b15d632be4..d6003dc8cc99 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_autoattach.c
@@ -5,14 +5,17 @@
 #include "test_uprobe_autoattach.skel.h"
 
 /* uprobe attach point */
-static void autoattach_trigger_func(void)
+static noinline int autoattach_trigger_func(int arg)
 {
 	asm volatile ("");
+	return arg + 1;
 }
 
 void test_uprobe_autoattach(void)
 {
 	struct test_uprobe_autoattach *skel;
+	int trigger_val = 100, trigger_ret;
+	size_t malloc_sz = 1;
 	char *mem;
 
 	skel = test_uprobe_autoattach__open_and_load();
@@ -22,17 +25,25 @@ void test_uprobe_autoattach(void)
 	if (!ASSERT_OK(test_uprobe_autoattach__attach(skel), "skel_attach"))
 		goto cleanup;
 
+	skel->bss->test_pid = getpid();
+
 	/* trigger & validate uprobe & uretprobe */
-	autoattach_trigger_func();
+	trigger_ret = autoattach_trigger_func(trigger_val);
+
+	skel->bss->test_pid = getpid();
 
 	/* trigger & validate shared library u[ret]probes attached by name */
-	mem = malloc(1);
+	mem = malloc(malloc_sz);
 	free(mem);
 
-	ASSERT_EQ(skel->bss->uprobe_byname_res, 1, "check_uprobe_byname_res");
-	ASSERT_EQ(skel->bss->uretprobe_byname_res, 2, "check_uretprobe_byname_res");
-	ASSERT_EQ(skel->bss->uprobe_byname2_res, 3, "check_uprobe_byname2_res");
-	ASSERT_EQ(skel->bss->uretprobe_byname2_res, 4, "check_uretprobe_byname2_res");
+	ASSERT_EQ(skel->bss->uprobe_byname_parm1, trigger_val, "check_uprobe_byname_parm1");
+	ASSERT_EQ(skel->bss->uprobe_byname_ran, 1, "check_uprobe_byname_ran");
+	ASSERT_EQ(skel->bss->uretprobe_byname_rc, trigger_ret, "check_uretprobe_byname_rc");
+	ASSERT_EQ(skel->bss->uretprobe_byname_ran, 2, "check_uretprobe_byname_ran");
+	ASSERT_EQ(skel->bss->uprobe_byname2_parm1, malloc_sz, "check_uprobe_byname2_parm1");
+	ASSERT_EQ(skel->bss->uprobe_byname2_ran, 3, "check_uprobe_byname2_ran");
+	ASSERT_EQ(skel->bss->uretprobe_byname2_rc, mem, "check_uretprobe_byname2_rc");
+	ASSERT_EQ(skel->bss->uretprobe_byname2_ran, 4, "check_uretprobe_byname2_ran");
 cleanup:
 	test_uprobe_autoattach__destroy(skel);
 }