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Date: Tue, 10 Jul 2018 13:36:44 +0100 From: Russell King <rmk+kernel@...linux.org.uk> To: netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org Cc: Daniel Borkmann <daniel@...earbox.net> Subject: [PATCH net-next 08/13] ARM: net: bpf: use immediate forms of instructions where possible Rather than moving constants to a register and then using them in a subsequent instruction, use them directly in the desired instruction cutting out the "middle" register. This removes two instructions from the tail call code path. Signed-off-by: Russell King <rmk+kernel@...linux.org.uk> --- arch/arm/net/bpf_jit_32.c | 16 +++++++++------- arch/arm/net/bpf_jit_32.h | 3 +++ 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 753b5b2b2e3d..c7591877c350 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -256,7 +256,7 @@ static u32 arm_bpf_ldst_imm12(u32 op, u8 rt, u8 rn, s16 imm12) op |= ARM_INST_LDST__U; else imm12 = -imm12; - return op | (imm12 & 0xfff); + return op | (imm12 & ARM_INST_LDST__IMM12); } static u32 arm_bpf_ldst_imm8(u32 op, u8 rt, u8 rn, s16 imm8) @@ -1012,11 +1012,12 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) /* if (index >= array->map.max_entries) * goto out; */ + 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 */ - emit_a32_mov_i(tmp[1], off, ctx); r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); - emit(ARM_LDR_R(tmp[1], r_array, tmp[1]), ctx); + emit(ARM_LDR_I(tmp[1], r_array, off), ctx); /* index is 32-bit for arrays */ r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); /* index >= array->map.max_entries */ @@ -1041,10 +1042,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) * if (prog == NULL) * goto out; */ + BUILD_BUG_ON(offsetof(struct bpf_array, ptrs) > ARM_ALU_IMM); off = offsetof(struct bpf_array, ptrs); - emit_a32_mov_i(tmp[1], off, ctx); r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); - emit(ARM_ADD_R(tmp[1], r_array, tmp[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); @@ -1052,9 +1053,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) _emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx); /* goto *(prog->bpf_func + prologue_size); */ + BUILD_BUG_ON(offsetof(struct bpf_prog, bpf_func) > + ARM_INST_LDST__IMM12); off = offsetof(struct bpf_prog, bpf_func); - emit_a32_mov_i(tmp2[1], off, ctx); - emit(ARM_LDR_R(tmp[1], tmp[1], tmp2[1]), ctx); + emit(ARM_LDR_I(tmp[1], tmp[1], off), ctx); emit(ARM_ADD_I(tmp[1], tmp[1], ctx->prologue_bytes), ctx); emit_bx_r(tmp[1], ctx); diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h index c55bc39d3e22..ca9f1f5589f4 100644 --- a/arch/arm/net/bpf_jit_32.h +++ b/arch/arm/net/bpf_jit_32.h @@ -78,6 +78,7 @@ #define ARM_INST_EOR_I 0x02200000 #define ARM_INST_LDST__U 0x00800000 +#define ARM_INST_LDST__IMM12 0x00000fff #define ARM_INST_LDRB_I 0x05500000 #define ARM_INST_LDRB_R 0x07d00000 #define ARM_INST_LDRH_I 0x015000b0 @@ -154,6 +155,8 @@ */ #define ARM_INST_UDF 0xe7fddef1 +#define ARM_ALU_IMM 0xff + /* register */ #define _AL3_R(op, rd, rn, rm) ((op ## _R) | (rd) << 12 | (rn) << 16 | (rm)) /* immediate */ -- 2.7.4
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