Adjust timer/timer_ret_1 test to validate more carefully verifier logic
of enforcing async callback return value. This test will pass only if
return result is marked precise and read.
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
.../selftests/bpf/progs/timer_failure.c | 36 ++++++++++++++-----
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/bpf/progs/timer_failure.c b/tools/testing/selftests/bpf/progs/timer_failure.c
index 9000da1e2120..a9f717d4e269 100644
--- a/tools/testing/selftests/bpf/progs/timer_failure.c
+++ b/tools/testing/selftests/bpf/progs/timer_failure.c
@@ -21,17 +21,37 @@ struct {
__type(value, struct elem);
} timer_map SEC(".maps");
-static int timer_cb_ret1(void *map, int *key, struct bpf_timer *timer)
+__naked __noinline __used
+static unsigned long timer_cb_ret_bad()
{
- if (bpf_get_smp_processor_id() % 2)
- return 1;
- else
- return 0;
+ asm volatile (
+ "call %[bpf_get_prandom_u32];"
+ "if r0 s> 1000 goto 1f;"
+ "r0 = 0;"
+ "1:"
+ "goto +0;" /* checkpoint */
+ /* async callback is expected to return 0, so branch above
+ * skipping r0 = 0; should lead to a failure, but if exit
+ * instruction doesn't enforce r0's precision, this callback
+ * will be successfully verified
+ */
+ "exit;"
+ :
+ : __imm(bpf_get_prandom_u32)
+ : __clobber_common
+ );
}
SEC("fentry/bpf_fentry_test1")
-__failure __msg("should have been in [0, 0]")
-int BPF_PROG2(test_ret_1, int, a)
+__log_level(2)
+__flag(BPF_F_TEST_STATE_FREQ)
+__failure
+/* check that fallthrough code path marks r0 as precise */
+__msg("mark_precise: frame0: regs=r0 stack= before 22: (b4) w0 = 0")
+/* check that branch code path marks r0 as precise */
+__msg("mark_precise: frame0: regs=r0 stack= before 24: (85) call bpf_get_prandom_u32#7")
+__msg("should have been in [0, 0]")
+int BPF_PROG2(test_bad_ret, int, a)
{
int key = 0;
struct bpf_timer *timer;
@@ -39,7 +59,7 @@ int BPF_PROG2(test_ret_1, int, a)
timer = bpf_map_lookup_elem(&timer_map, &key);
if (timer) {
bpf_timer_init(timer, &timer_map, CLOCK_BOOTTIME);
- bpf_timer_set_callback(timer, timer_cb_ret1);
+ bpf_timer_set_callback(timer, timer_cb_ret_bad);
bpf_timer_start(timer, 1000, 0);
}
--
2.34.1
