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Message-Id: <E1ieH2g-0004ih-Rb@rmk-PC.armlinux.org.uk> Date: Mon, 09 Dec 2019 11:17:30 +0000 From: Russell King <rmk+kernel@...linux.org.uk> To: Daniel Borkmann <daniel@...earbox.net> Cc: Shubham Bansal <illusionist.neo@...il.com>, Alexei Starovoitov <ast@...nel.org>, Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, Andrii Nakryiko <andriin@...com>, netdev@...r.kernel.org, bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org Subject: [PATCH] ARM: net: bpf: improve prologue code sequence Improve the prologue code sequence to be able to take advantage of 64-bit stores, changing the code from: push {r4, r5, r6, r7, r8, r9, fp, lr} mov fp, sp sub ip, sp, #80 ; 0x50 sub sp, sp, #600 ; 0x258 str ip, [fp, #-100] ; 0xffffff9c mov r6, #0 str r6, [fp, #-96] ; 0xffffffa0 mov r4, #0 mov r3, r4 mov r2, r0 str r4, [fp, #-104] ; 0xffffff98 str r4, [fp, #-108] ; 0xffffff94 to the tighter: push {r4, r5, r6, r7, r8, r9, fp, lr} mov fp, sp mov r3, #0 sub r2, sp, #80 ; 0x50 sub sp, sp, #600 ; 0x258 strd r2, [fp, #-100] ; 0xffffff9c mov r2, #0 strd r2, [fp, #-108] ; 0xffffff94 mov r2, r0 resulting in a saving of three instructions. Signed-off-by: Russell King <rmk+kernel@...linux.org.uk> --- arch/arm/net/bpf_jit_32.c | 30 +++++++++++++----------------- 1 file changed, 13 insertions(+), 17 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 97dc386e3cb8..cc29869d12a3 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1260,12 +1260,9 @@ static inline void emit_push_r64(const s8 src[], struct jit_ctx *ctx) static void build_prologue(struct jit_ctx *ctx) { - const s8 r0 = bpf2a32[BPF_REG_0][1]; - const s8 r2 = bpf2a32[BPF_REG_1][1]; - const s8 r3 = bpf2a32[BPF_REG_1][0]; - const s8 r4 = bpf2a32[BPF_REG_6][1]; - const s8 fplo = bpf2a32[BPF_REG_FP][1]; - const s8 fphi = bpf2a32[BPF_REG_FP][0]; + const s8 arm_r0 = bpf2a32[BPF_REG_0][1]; + const s8 *bpf_r1 = bpf2a32[BPF_REG_1]; + const s8 *bpf_fp = bpf2a32[BPF_REG_FP]; const s8 *tcc = bpf2a32[TCALL_CNT]; /* Save callee saved registers. */ @@ -1278,8 +1275,10 @@ static void build_prologue(struct jit_ctx *ctx) emit(ARM_PUSH(CALLEE_PUSH_MASK), ctx); emit(ARM_MOV_R(ARM_FP, ARM_SP), ctx); #endif - /* Save frame pointer for later */ - emit(ARM_SUB_I(ARM_IP, ARM_SP, SCRATCH_SIZE), ctx); + /* mov r3, #0 */ + /* sub r2, sp, #SCRATCH_SIZE */ + emit(ARM_MOV_I(bpf_r1[0], 0), ctx); + emit(ARM_SUB_I(bpf_r1[1], ARM_SP, SCRATCH_SIZE), ctx); ctx->stack_size = imm8m(STACK_SIZE); @@ -1287,18 +1286,15 @@ static void build_prologue(struct jit_ctx *ctx) emit(ARM_SUB_I(ARM_SP, ARM_SP, ctx->stack_size), ctx); /* Set up BPF prog stack base register */ - emit_a32_mov_r(fplo, ARM_IP, ctx); - emit_a32_mov_i(fphi, 0, ctx); + emit_a32_mov_r64(true, bpf_fp, bpf_r1, ctx); - /* mov r4, 0 */ - emit(ARM_MOV_I(r4, 0), ctx); + /* Initialize Tail Count */ + emit(ARM_MOV_I(bpf_r1[1], 0), ctx); + emit_a32_mov_r64(true, tcc, bpf_r1, ctx); /* Move BPF_CTX to BPF_R1 */ - emit(ARM_MOV_R(r3, r4), ctx); - emit(ARM_MOV_R(r2, r0), ctx); - /* Initialize Tail Count */ - emit(ARM_STR_I(r4, ARM_FP, EBPF_SCRATCH_TO_ARM_FP(tcc[0])), ctx); - emit(ARM_STR_I(r4, ARM_FP, EBPF_SCRATCH_TO_ARM_FP(tcc[1])), ctx); + emit(ARM_MOV_R(bpf_r1[1], arm_r0), ctx); + /* end of prologue */ } -- 2.20.1
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