diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/test_global_func15.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_global_func15.c | 34 |
1 files changed, 33 insertions, 1 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_global_func15.c b/tools/testing/selftests/bpf/progs/test_global_func15.c index b512d6a6c75e..b4e089d6981d 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func15.c +++ b/tools/testing/selftests/bpf/progs/test_global_func15.c @@ -13,7 +13,7 @@ __noinline int foo(unsigned int *v) } SEC("cgroup_skb/ingress") -__failure __msg("At program exit the register R0 has value") +__failure __msg("At program exit the register R0 has ") int global_func15(struct __sk_buff *skb) { unsigned int v = 1; @@ -22,3 +22,35 @@ int global_func15(struct __sk_buff *skb) return v; } + +SEC("cgroup_skb/ingress") +__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 2: (b7) r0 = 1") +/* check that branch code path marks r0 as precise */ +__msg("mark_precise: frame0: regs=r0 stack= before 0: (85) call bpf_get_prandom_u32#7") +__msg("At program exit the register R0 has ") +__naked int global_func15_tricky_pruning(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "if r0 s> 1000 goto 1f;" + "r0 = 1;" + "1:" + "goto +0;" /* checkpoint */ + /* cgroup_skb/ingress program is expected to return [0, 1] + * values, so branch above makes sure that in a fallthrough + * case we have a valid 1 stored in R0 register, but in + * a branch case we assign some random value to R0. So if + * there is something wrong with precision tracking for R0 at + * program exit, we might erronenously prune branch case, + * because R0 in fallthrough case is imprecise (and thus any + * value is valid from POV of verifier is_state_equal() logic) + */ + "exit;" + : + : __imm(bpf_get_prandom_u32) + : __clobber_common + ); +} |