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Date: Wed, 11 Jul 2018 10:32:12 +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 v2 09/14] 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 | 21 ++++++++++++--------- arch/arm/net/bpf_jit_32.h | 1 + 2 files changed, 13 insertions(+), 9 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 2cc66aa44dfe..645653e1931e 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -304,7 +304,7 @@ 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) @@ -1054,17 +1054,19 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) const int idx0 = ctx->idx; #define cur_offset (ctx->idx - idx0) #define jmp_offset (out_offset - (cur_offset) - 2) - u32 off, lo, hi; + u32 lo, hi; s8 r_array, r_index; + int off; /* 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 */ @@ -1089,10 +1091,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) * if (prog == NULL) * goto out; */ - off = offsetof(struct bpf_array, ptrs); - emit_a32_mov_i(tmp[1], off, 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[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); @@ -1100,9 +1102,10 @@ 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..dee8a76fb0bc 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 -- 2.7.4
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