From b50452299864fbc00a576241e1490541c8754d50 Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 11 Jul 2018 10:32:28 +0100 Subject: [PATCH] ARM: net: bpf: avoid reloading 'array' Rearranging the order of the initial tail call code a little allows is to avoid reloading the 'array' pointer. Signed-off-by: Russell King Signed-off-by: Daniel Borkmann --- arch/arm/net/bpf_jit_32.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 0a8b3d0..f0cad96 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1064,16 +1064,16 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) BUILD_BUG_ON(offsetof(struct bpf_array, map.max_entries) > ARM_INST_LDST__IMM12); off = offsetof(struct bpf_array, map.max_entries); - /* array->map.max_entries */ - r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); - emit(ARM_LDR_I(tmp[1], r_array, off), ctx); + r_array = arm_bpf_get_reg32(r2[1], tmp2[0], ctx); /* index is 32-bit for arrays */ r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); + /* array->map.max_entries */ + emit(ARM_LDR_I(tmp[1], r_array, off), ctx); /* index >= array->map.max_entries */ emit(ARM_CMP_R(r_index, tmp[1]), ctx); _emit(ARM_COND_CS, ARM_B(jmp_offset), ctx); - /* tmp2[1] = index */ + /* tmp2[0] = array, tmp2[1] = index */ /* if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; @@ -1095,7 +1095,6 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) */ BUILD_BUG_ON(imm8m(offsetof(struct bpf_array, ptrs)) < 0); off = imm8m(offsetof(struct bpf_array, ptrs)); - r_array = arm_bpf_get_reg32(r2[1], tmp2[0], ctx); emit(ARM_ADD_I(tmp[1], r_array, off), ctx); emit(ARM_LDR_R_SI(tmp[1], tmp[1], r_index, SRTYPE_ASL, 2), ctx); emit(ARM_CMP_I(tmp[1], 0), ctx); -- 2.7.4