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Message-ID: <175852293339.307379.8831172703363408291.stgit@devnote2>
Date: Mon, 22 Sep 2025 15:35:33 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...nel.org>,
Menglong Dong <menglong8.dong@...il.com>
Cc: jolsa@...nel.org,
tglx@...utronix.de,
mingo@...hat.com,
bp@...en8.de,
dave.hansen@...ux.intel.com,
x86@...nel.org,
hpa@...or.com,
kees@...nel.org,
samitolvanen@...gle.com,
rppt@...nel.org,
luto@...nel.org,
mhiramat@...nel.org,
ast@...nel.org,
andrii@...nel.org,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: [PATCH v2 2/2] lib/test_fprobe: Add recursion check test cases
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Add test cases for checking recursion level must be less than 2.
This ensures that fprobe can prevent infinite recursive call by
itself.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
lib/tests/test_fprobe.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 90 insertions(+), 2 deletions(-)
diff --git a/lib/tests/test_fprobe.c b/lib/tests/test_fprobe.c
index cf92111b5c79..0022da242a83 100644
--- a/lib/tests/test_fprobe.c
+++ b/lib/tests/test_fprobe.c
@@ -17,8 +17,10 @@ static u32 rand1, entry_val, exit_val;
/* Use indirect calls to avoid inlining the target functions */
static u32 (*target)(u32 value);
static u32 (*target2)(u32 value);
+static u32 (*target3)(u32 value);
static unsigned long target_ip;
static unsigned long target2_ip;
+static unsigned long target3_ip;
static int entry_return_value;
static noinline u32 fprobe_selftest_target(u32 value)
@@ -31,13 +33,18 @@ static noinline u32 fprobe_selftest_target2(u32 value)
return (value / div_factor) + 1;
}
+static noinline u32 fprobe_selftest_target3(u32 value)
+{
+ return (value / div_factor) + 2;
+}
+
static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
- if (ip != target_ip)
+ if (ip != target_ip && ip != target3_ip)
KUNIT_EXPECT_EQ(current_test, ip, target2_ip);
entry_val = (rand1 / div_factor);
if (fp->entry_data_size) {
@@ -190,6 +197,84 @@ static void test_fprobe_skip(struct kunit *test)
KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
}
+static int recur_count;
+static int recur_high;
+
+static notrace int fp_recur_entry_handler(struct fprobe *fp, unsigned long ip,
+ unsigned long ret_ip,
+ struct ftrace_regs *fregs, void *data)
+{
+ /* fgraph/fprobe allows one-level nesting. */
+ if (recur_count > 1)
+ return 0;
+
+ recur_count++;
+ if (recur_count > recur_high)
+ recur_high = recur_count;
+ target3(rand1);
+ recur_count--;
+
+ return 0;
+}
+
+static notrace void fp_recur_exit_handler(struct fprobe *fp, unsigned long ip,
+ unsigned long ret_ip,
+ struct ftrace_regs *fregs, void *data)
+{
+ /* fgraph/fprobe allows one-level nesting. */
+ if (recur_count > 1)
+ return;
+
+ recur_count++;
+ if (recur_count > recur_high)
+ recur_high = recur_count;
+ target3(rand1);
+ recur_count--;
+}
+
+static void test_fprobe_recursion_entry(struct kunit *test)
+{
+ struct fprobe fp = {
+ .entry_handler = fp_recur_entry_handler,
+ };
+ struct fprobe fp3 = {
+ .entry_handler = fp_recur_entry_handler,
+ };
+
+ current_test = test;
+ recur_count = 0;
+ recur_high = 0;
+ KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL));
+ KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp3, "fprobe_selftest_target3", NULL));
+
+ target(rand1);
+
+ KUNIT_EXPECT_LE(test, recur_high, 2);
+ KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp3));
+ KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
+}
+
+static void test_fprobe_recursion_exit(struct kunit *test)
+{
+ struct fprobe fp = {
+ .exit_handler = fp_recur_exit_handler,
+ };
+ struct fprobe fp3 = {
+ .exit_handler = fp_recur_exit_handler,
+ };
+
+ current_test = test;
+ recur_count = 0;
+ KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp, "fprobe_selftest_target", NULL));
+ KUNIT_EXPECT_EQ(test, 0, register_fprobe(&fp3, "fprobe_selftest_target3", NULL));
+
+ target(rand1);
+
+ KUNIT_EXPECT_LE(test, recur_high, 2);
+ KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp3));
+ KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
+}
+
static unsigned long get_ftrace_location(void *func)
{
unsigned long size, addr = (unsigned long)func;
@@ -205,8 +290,10 @@ static int fprobe_test_init(struct kunit *test)
rand1 = get_random_u32_above(div_factor);
target = fprobe_selftest_target;
target2 = fprobe_selftest_target2;
+ target3 = fprobe_selftest_target3;
target_ip = get_ftrace_location(target);
target2_ip = get_ftrace_location(target2);
+ target3_ip = get_ftrace_location(target3);
return 0;
}
@@ -217,6 +304,8 @@ static struct kunit_case fprobe_testcases[] = {
KUNIT_CASE(test_fprobe_syms),
KUNIT_CASE(test_fprobe_data),
KUNIT_CASE(test_fprobe_skip),
+ KUNIT_CASE(test_fprobe_recursion_entry),
+ KUNIT_CASE(test_fprobe_recursion_exit),
{}
};
@@ -227,4 +316,3 @@ static struct kunit_suite fprobe_test_suite = {
};
kunit_test_suites(&fprobe_test_suite);
-
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