[PATCH v2 bpf-next 1/4] bpf: speed up stacksafe check

[Alexei Starovoitov]

Don't check the same stack liveness condition 8 times.
once is enough.

Signed-off-by: Alexei Starovoitov <a...@kernel.org>
Acked-by: Edward Cree <ec...@solarflare.com>
Acked-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 kernel/bpf/verifier.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8b511a4fe84a..d4db4727a50e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5147,9 +5147,11 @@ static bool stacksafe(struct bpf_func_state *old,
        for (i = 0; i < old->allocated_stack; i++) {
                spi = i / BPF_REG_SIZE;
 
-               if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ))
+               if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)) {
+                       i += BPF_REG_SIZE - 1;
                        /* explored state didn't use this */
                        continue;
+               }
 
                if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == 
STACK_INVALID)
                        continue;
-- 
2.17.1