net: filter: make JITs zero A for SKF_AD_ALU_XOR_X

[deliverable/linux.git] / include / linux / filter.h

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 4165e9ac9e36aa82735f40a790e25e0b7218c95b..5972ffe5719a4e14012328035450759c12f43bec 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -493,6 +493,25 @@ static inline void bpf_jit_free(struct bpf_prog *fp)
 
 #define BPF_ANC                BIT(15)
 
+static inline bool bpf_needs_clear_a(const struct sock_filter *first)
+{
+       switch (first->code) {
+       case BPF_RET | BPF_K:
+       case BPF_LD | BPF_W | BPF_LEN:
+               return false;
+
+       case BPF_LD | BPF_W | BPF_ABS:
+       case BPF_LD | BPF_H | BPF_ABS:
+       case BPF_LD | BPF_B | BPF_ABS:
+               if (first->k == SKF_AD_OFF + SKF_AD_ALU_XOR_X)
+                       return true;
+               return false;
+
+       default:
+               return true;
+       }
+}
+
 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 {
        BUG_ON(ftest->code & BPF_ANC);