net: filter: move load_pointer() into filter.h

load_pointer() is already a static inline function.
Let's move it into filter.h so BPF JIT implementations can reuse this
function.

Since we're exporting this function, let's also rename it to
bpf_load_pointer() for clarity.
Signed-off-by: NZi Shen Lim <zlim.lnx@gmail.com>
Reviewed-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/filter.h

@@ -6,6 +6,7 @@
 
 #include <linux/atomic.h>
 #include <linux/compat.h>
+#include <linux/skbuff.h>
 #include <linux/workqueue.h>
 #include <uapi/linux/filter.h>
 
@@ -406,6 +407,18 @@ static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 	}
 }
 
+void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
+					   int k, unsigned int size);
+
+static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
+				     unsigned int size, void *buffer)
+{
+	if (k >= 0)
+		return skb_header_pointer(skb, k, size, buffer);
+
+	return bpf_internal_load_pointer_neg_helper(skb, k, size);
+}
+
 #ifdef CONFIG_BPF_JIT
 #include <stdarg.h>
 #include <linux/linkage.h>

net/core/filter.c

@@ -84,15 +84,6 @@ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, uns
 	return NULL;
 }
 
-static inline void *load_pointer(const struct sk_buff *skb, int k,
-				 unsigned int size, void *buffer)
-{
-	if (k >= 0)
-		return skb_header_pointer(skb, k, size, buffer);
-
-	return bpf_internal_load_pointer_neg_helper(skb, k, size);
-}
-
 /**
  *	sk_filter - run a packet through a socket filter
  *	@sk: sock associated with &sk_buff
@@ -537,7 +528,7 @@ static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *ins
 		 *   BPF_R0 - 8/16/32-bit skb data converted to cpu endianness
 		 */
 
-		ptr = load_pointer((struct sk_buff *) (unsigned long) CTX, off, 4, &tmp);
+		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 4, &tmp);
 		if (likely(ptr != NULL)) {
 			BPF_R0 = get_unaligned_be32(ptr);
 			CONT;
@@ -547,7 +538,7 @@ static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *ins
 	LD_ABS_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + imm32)) */
 		off = IMM;
 load_half:
-		ptr = load_pointer((struct sk_buff *) (unsigned long) CTX, off, 2, &tmp);
+		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 2, &tmp);
 		if (likely(ptr != NULL)) {
 			BPF_R0 = get_unaligned_be16(ptr);
 			CONT;
@@ -557,7 +548,7 @@ static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *ins
 	LD_ABS_B: /* BPF_R0 = *(u8 *) (skb->data + imm32) */
 		off = IMM;
 load_byte:
-		ptr = load_pointer((struct sk_buff *) (unsigned long) CTX, off, 1, &tmp);
+		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 1, &tmp);
 		if (likely(ptr != NULL)) {
 			BPF_R0 = *(u8 *)ptr;
 			CONT;