netdev - [PATCH bpf-next 08/12] bpf, arm32: remove ld_abs/ld

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Date:   Thu,  3 May 2018 03:05:32 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     ast@...nel.org
Cc:     netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf-next 08/12] bpf, arm32: remove ld_abs/ld_ind

Since LD_ABS/LD_IND instructions are now removed from the core and
reimplemented through a combination of inlined BPF instructions and
a slow-path helper, we can get rid of the complexity from arm32 JIT.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
 arch/arm/net/bpf_jit_32.c | 77 -----------------------------------------------
 1 file changed, 77 deletions(-)

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index b5030e1..82689b9 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -1452,83 +1452,6 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 			emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_lo)), ctx);
 		emit_ldx_r(dst, rn, dstk, off, ctx, BPF_SIZE(code));
 		break;
-	/* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */
-	case BPF_LD | BPF_ABS | BPF_W:
-	case BPF_LD | BPF_ABS | BPF_H:
-	case BPF_LD | BPF_ABS | BPF_B:
-	/* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + src + imm)) */
-	case BPF_LD | BPF_IND | BPF_W:
-	case BPF_LD | BPF_IND | BPF_H:
-	case BPF_LD | BPF_IND | BPF_B:
-	{
-		const u8 r4 = bpf2a32[BPF_REG_6][1]; /* r4 = ptr to sk_buff */
-		const u8 r0 = bpf2a32[BPF_REG_0][1]; /*r0: struct sk_buff *skb*/
-						     /* rtn value */
-		const u8 r1 = bpf2a32[BPF_REG_0][0]; /* r1: int k */
-		const u8 r2 = bpf2a32[BPF_REG_1][1]; /* r2: unsigned int size */
-		const u8 r3 = bpf2a32[BPF_REG_1][0]; /* r3: void *buffer */
-		const u8 r6 = bpf2a32[TMP_REG_1][1]; /* r6: void *(*func)(..) */
-		int size;
-
-		/* Setting up first argument */
-		emit(ARM_MOV_R(r0, r4), ctx);
-
-		/* Setting up second argument */
-		emit_a32_mov_i(r1, imm, false, ctx);
-		if (BPF_MODE(code) == BPF_IND)
-			emit_a32_alu_r(r1, src_lo, false, sstk, ctx,
-				       false, false, BPF_ADD);
-
-		/* Setting up third argument */
-		switch (BPF_SIZE(code)) {
-		case BPF_W:
-			size = 4;
-			break;
-		case BPF_H:
-			size = 2;
-			break;
-		case BPF_B:
-			size = 1;
-			break;
-		default:
-			return -EINVAL;
-		}
-		emit_a32_mov_i(r2, size, false, ctx);
-
-		/* Setting up fourth argument */
-		emit(ARM_ADD_I(r3, ARM_SP, imm8m(SKB_BUFFER)), ctx);
-
-		/* Setting up function pointer to call */
-		emit_a32_mov_i(r6, (unsigned int)bpf_load_pointer, false, ctx);
-		emit_blx_r(r6, ctx);
-
-		emit(ARM_EOR_R(r1, r1, r1), ctx);
-		/* Check if return address is NULL or not.
-		 * if NULL then jump to epilogue
-		 * else continue to load the value from retn address
-		 */
-		emit(ARM_CMP_I(r0, 0), ctx);
-		jmp_offset = epilogue_offset(ctx);
-		check_imm24(jmp_offset);
-		_emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx);
-
-		/* Load value from the address */
-		switch (BPF_SIZE(code)) {
-		case BPF_W:
-			emit(ARM_LDR_I(r0, r0, 0), ctx);
-			emit_rev32(r0, r0, ctx);
-			break;
-		case BPF_H:
-			emit(ARM_LDRH_I(r0, r0, 0), ctx);
-			emit_rev16(r0, r0, ctx);
-			break;
-		case BPF_B:
-			emit(ARM_LDRB_I(r0, r0, 0), ctx);
-			/* No need to reverse */
-			break;
-		}
-		break;
-	}
 	/* ST: *(size *)(dst + off) = imm */
 	case BPF_ST | BPF_MEM | BPF_W:
 	case BPF_ST | BPF_MEM | BPF_H:
-- 
2.9.5