Add testcase for the logic that the verifier tracks the BPF_JNE for regs.
The assembly function "reg_not_equal()" that we add is exactly converted
from the following case:
u32 a = bpf_get_prandom_u32();
u64 b = 0;
a %= 8;
/* the "a > 0" here will be optimized to "a != 0" */
if (a > 0) {
/* now the range of a should be [1, 7] */
bpf_skb_store_bytes(skb, 0, &b, a, 0);
}
Signed-off-by: Menglong Dong <menglong8.dong@xxxxxxxxx>
---
.../selftests/bpf/progs/verifier_bounds.c | 27 +++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c
index ec430b71730b..3fe2ce2b3f21 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bounds.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c
@@ -1075,4 +1075,31 @@ l0_%=: r0 = 0; \
: __clobber_all);
}
+SEC("tc")
+__description("bounds check with JMP_NE for reg edge")
+__success __retval(0)
+__naked void reg_not_equal(void)
+{
+ asm volatile (" \
+ r6 = r1; \
+ r1 = 0; \
+ *(u64*)(r10 - 8) = r1; \
+ call %[bpf_get_prandom_u32]; \
+ r4 = r0; \
+ r4 &= 7; \
+ if r4 == 0 goto l0_%=; \
+ r1 = r6; \
+ r2 = 0; \
+ r3 = r10; \
+ r3 += -8; \
+ r5 = 0; \
+ call %[bpf_skb_store_bytes]; \
+l0_%=: r0 = 0; \
+ exit; \
+" :
+ : __imm(bpf_get_prandom_u32),
+ __imm(bpf_skb_store_bytes)
+ : __clobber_all);
+}
+
char _license[] SEC("license") = "GPL";
--
2.39.2
