From: Russell King Date: Wed, 11 Jul 2018 09:32:17 +0000 (+0100) Subject: ARM: net: bpf: use ldr instructions with shifted rm register X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2b6958ef1151452cb2160fde75a5c5382b512c34;p=linux.git ARM: net: bpf: use ldr instructions with shifted rm register Rather than pre-shifting the rm register for the ldr in the tail call, shift it in the load instruction. This eliminates one unnecessary instruction. Signed-off-by: Russell King Signed-off-by: Daniel Borkmann --- diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 645653e1931e4..e22dc828420cf 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1096,8 +1096,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); emit(ARM_ADD_I(tmp[1], r_array, off), ctx); r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); - emit(ARM_MOV_SI(tmp[0], r_index, SRTYPE_ASL, 2), ctx); - emit(ARM_LDR_R(tmp[1], tmp[1], tmp[0]), ctx); + emit(ARM_LDR_R_SI(tmp[1], tmp[1], r_index, SRTYPE_ASL, 2), ctx); emit(ARM_CMP_I(tmp[1], 0), ctx); _emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx); diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h index dee8a76fb0bcb..e541a7a6139a8 100644 --- a/arch/arm/net/bpf_jit_32.h +++ b/arch/arm/net/bpf_jit_32.h @@ -188,6 +188,10 @@ #define ARM_LDR_R(rt, rn, rm) (ARM_INST_LDR_R | ARM_INST_LDST__U \ | (rt) << 12 | (rn) << 16 \ | (rm)) +#define ARM_LDR_R_SI(rt, rn, rm, type, imm) \ + (ARM_INST_LDR_R | ARM_INST_LDST__U \ + | (rt) << 12 | (rn) << 16 \ + | (imm) << 7 | (type) << 5 | (rm)) #define ARM_LDRB_R(rt, rn, rm) (ARM_INST_LDRB_R | ARM_INST_LDST__U \ | (rt) << 12 | (rn) << 16 \ | (rm))