From e5f02caccfae94f5baf6ec6dbb57ce8a7e9a40e7 Mon Sep 17 00:00:00 2001 From: Brendan Jackman Date: Thu, 14 Jan 2021 18:17:43 +0000 Subject: bpf: x86: Factor out a lookup table for some ALU opcodes A later commit will need to lookup a subset of these opcodes. To avoid duplicating code, pull out a table. The shift opcodes won't be needed by that later commit, but they're already duplicated, so fold them into the table anyway. Signed-off-by: Brendan Jackman Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20210114181751.768687-4-jackmanb@google.com --- arch/x86/net/bpf_jit_comp.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index f15c93275a18..93f32e0ba0ef 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -205,6 +205,18 @@ static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg) return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3); } +/* Some 1-byte opcodes for binary ALU operations */ +static u8 simple_alu_opcodes[] = { + [BPF_ADD] = 0x01, + [BPF_SUB] = 0x29, + [BPF_AND] = 0x21, + [BPF_OR] = 0x09, + [BPF_XOR] = 0x31, + [BPF_LSH] = 0xE0, + [BPF_RSH] = 0xE8, + [BPF_ARSH] = 0xF8, +}; + static void jit_fill_hole(void *area, unsigned int size) { /* Fill whole space with INT3 instructions */ @@ -862,15 +874,9 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, case BPF_ALU64 | BPF_AND | BPF_X: case BPF_ALU64 | BPF_OR | BPF_X: case BPF_ALU64 | BPF_XOR | BPF_X: - switch (BPF_OP(insn->code)) { - case BPF_ADD: b2 = 0x01; break; - case BPF_SUB: b2 = 0x29; break; - case BPF_AND: b2 = 0x21; break; - case BPF_OR: b2 = 0x09; break; - case BPF_XOR: b2 = 0x31; break; - } maybe_emit_mod(&prog, dst_reg, src_reg, BPF_CLASS(insn->code) == BPF_ALU64); + b2 = simple_alu_opcodes[BPF_OP(insn->code)]; EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); break; @@ -1050,12 +1056,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); - switch (BPF_OP(insn->code)) { - case BPF_LSH: b3 = 0xE0; break; - case BPF_RSH: b3 = 0xE8; break; - case BPF_ARSH: b3 = 0xF8; break; - } - + b3 = simple_alu_opcodes[BPF_OP(insn->code)]; if (imm32 == 1) EMIT2(0xD1, add_1reg(b3, dst_reg)); else @@ -1089,11 +1090,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, else if (is_ereg(dst_reg)) EMIT1(add_1mod(0x40, dst_reg)); - switch (BPF_OP(insn->code)) { - case BPF_LSH: b3 = 0xE0; break; - case BPF_RSH: b3 = 0xE8; break; - case BPF_ARSH: b3 = 0xF8; break; - } + b3 = simple_alu_opcodes[BPF_OP(insn->code)]; EMIT2(0xD3, add_1reg(b3, dst_reg)); if (src_reg != BPF_REG_4) -- cgit