net: filter: make BPF conversion more readable

Introduce BPF helper macros to define instructions
(similar to old BPF_STMT/BPF_JUMP macros)

Use them while converting classic BPF to internal
and in BPF testsuite later.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 0 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index ed1efab10b8f..4457b383961c 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -79,6 +79,57 @@ enum {
 /* BPF program can access up to 512 bytes of stack space. */
 #define MAX_BPF_STACK	512
 
+/* bpf_add|sub|...: a += x, bpf_mov: a = x */
+#define BPF_ALU64_REG(op, a, x) \
+	((struct sock_filter_int) {BPF_ALU64|BPF_OP(op)|BPF_X, a, x, 0, 0})
+#define BPF_ALU32_REG(op, a, x) \
+	((struct sock_filter_int) {BPF_ALU|BPF_OP(op)|BPF_X, a, x, 0, 0})
+
+/* bpf_add|sub|...: a += imm, bpf_mov: a = imm */
+#define BPF_ALU64_IMM(op, a, imm) \
+	((struct sock_filter_int) {BPF_ALU64|BPF_OP(op)|BPF_K, a, 0, 0, imm})
+#define BPF_ALU32_IMM(op, a, imm) \
+	((struct sock_filter_int) {BPF_ALU|BPF_OP(op)|BPF_K, a, 0, 0, imm})
+
+/* R0 = *(uint *) (skb->data + off) */
+#define BPF_LD_ABS(size, off) \
+	((struct sock_filter_int) {BPF_LD|BPF_SIZE(size)|BPF_ABS, 0, 0, 0, off})
+
+/* R0 = *(uint *) (skb->data + x + off) */
+#define BPF_LD_IND(size, x, off) \
+	((struct sock_filter_int) {BPF_LD|BPF_SIZE(size)|BPF_IND, 0, x, 0, off})
+
+/* a = *(uint *) (x + off) */
+#define BPF_LDX_MEM(sz, a, x, off) \
+	((struct sock_filter_int) {BPF_LDX|BPF_SIZE(sz)|BPF_MEM, a, x, off, 0})
+
+/* if (a 'op' x) goto pc+off */
+#define BPF_JMP_REG(op, a, x, off) \
+	((struct sock_filter_int) {BPF_JMP|BPF_OP(op)|BPF_X, a, x, off, 0})
+
+/* if (a 'op' imm) goto pc+off */
+#define BPF_JMP_IMM(op, a, imm, off) \
+	((struct sock_filter_int) {BPF_JMP|BPF_OP(op)|BPF_K, a, 0, off, imm})
+
+#define BPF_EXIT_INSN() \
+	((struct sock_filter_int) {BPF_JMP|BPF_EXIT, 0, 0, 0, 0})
+
+static inline int size_to_bpf(int size)
+{
+	switch (size) {
+	case 1:
+		return BPF_B;
+	case 2:
+		return BPF_H;
+	case 4:
+		return BPF_W;
+	case 8:
+		return BPF_DW;
+	default:
+		return -EINVAL;
+	}
+}
+
 /* Macro to invoke filter function. */
 #define SK_RUN_FILTER(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)