[PATCH bpf-next v1 2/2] bpf/selftest: add selftest for may_goto

[Jiayuan Chen <mrpre@163.com>]

Add test case to ensure normal operation when may_goto exists and the
stack size has already reached 512.

./test_progs -t verifier_stack_ptr
...
verifier_stack_ptr/PTR_TO_STACK max stack size > 512:OK
verifier_stack_ptr/PTR_TO_STACK max stack size 512 with may_goto:OK
...

Signed-off-by: Jiayuan Chen <mrpre@163.com>
---
 .../selftests/bpf/progs/verifier_stack_ptr.c  | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c b/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c
index 417c61cd4b19..b2e84714e1bc 100644
--- a/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c
+++ b/tools/testing/selftests/bpf/progs/verifier_stack_ptr.c
@@ -481,4 +481,37 @@ l1_%=:	r0 = 42;					\
 	: __clobber_all);
 }
 
+SEC("socket")
+__description("PTR_TO_STACK max stack size > 512")
+__failure __msg("invalid write to stack R1 off=-520 size=8")
+__naked void stack_check_size_gt_512(void)
+{
+	asm volatile (
+	"r1 = r10;"
+	"r1 += -520;"
+	"r0 = 42;"
+	"*(u64*)(r1 + 0) = r0;"
+	"exit;"
+	::: __clobber_all);
+}
+
+#ifdef __BPF_FEATURE_MAY_GOTO
+SEC("socket")
+__description("PTR_TO_STACK max stack size 512 with may_goto")
+__success
+__retval(42)
+__naked void stack_check_size_512_with_may_goto(void)
+{
+	asm volatile (
+	"r1 = r10;"
+	"r1 += -512;"
+	"r0 = 42;"
+	"*(u32*)(r1 + 0) = r0;"
+	"may_goto end;"
+	"r2 = 100;"
+"end:	exit;"
+	::: __clobber_all);
+}
+#endif
+
 char _license[] SEC("license") = "GPL";
-- 
2.47.1