diff options
| author | Jie Meng <jmeng@fb.com> | 2021-09-14 00:13:37 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-09-15 04:36:36 +0300 |
| commit | c0354077439bc9adcc9f2c96d6bbaf8b13748317 (patch) | |
| tree | a17537ada6a89d129640bf568c2d0ea38d1c4541 /arch/x86/net/bpf_jit_comp.c | |
| parent | 67dfac47dac67a44d5bbdab2541a35ce33a2729a (diff) | |
| download | linux-c0354077439bc9adcc9f2c96d6bbaf8b13748317.tar.xz | |
bpf,x64 Emit IMUL instead of MUL for x86-64
IMUL allows for multiple operands and saving and storing rax/rdx is no
longer needed. Signedness of the operands doesn't matter here because
the we only keep the lower 32/64 bit of the product for 32/64 bit
multiplications.
Signed-off-by: Jie Meng <jmeng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210913211337.1564014-1-jmeng@fb.com
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 53 |
1 files changed, 23 insertions, 30 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 0fe6aacef3db..20d2d6a1f9de 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1070,41 +1070,34 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, break; case BPF_ALU | BPF_MUL | BPF_K: - case BPF_ALU | BPF_MUL | BPF_X: case BPF_ALU64 | BPF_MUL | BPF_K: - case BPF_ALU64 | BPF_MUL | BPF_X: - { - bool is64 = BPF_CLASS(insn->code) == BPF_ALU64; + if (BPF_CLASS(insn->code) == BPF_ALU64) + EMIT1(add_2mod(0x48, dst_reg, dst_reg)); + else if (is_ereg(dst_reg)) + EMIT1(add_2mod(0x40, dst_reg, dst_reg)); - if (dst_reg != BPF_REG_0) - EMIT1(0x50); /* push rax */ - if (dst_reg != BPF_REG_3) - EMIT1(0x52); /* push rdx */ + if (is_imm8(imm32)) + /* imul dst_reg, dst_reg, imm8 */ + EMIT3(0x6B, add_2reg(0xC0, dst_reg, dst_reg), + imm32); + else + /* imul dst_reg, dst_reg, imm32 */ + EMIT2_off32(0x69, + add_2reg(0xC0, dst_reg, dst_reg), + imm32); + break; - /* mov r11, dst_reg */ - EMIT_mov(AUX_REG, dst_reg); + case BPF_ALU | BPF_MUL | BPF_X: + case BPF_ALU64 | BPF_MUL | BPF_X: + if (BPF_CLASS(insn->code) == BPF_ALU64) + EMIT1(add_2mod(0x48, src_reg, dst_reg)); + else if (is_ereg(dst_reg) || is_ereg(src_reg)) + EMIT1(add_2mod(0x40, src_reg, dst_reg)); - if (BPF_SRC(insn->code) == BPF_X) - emit_mov_reg(&prog, is64, BPF_REG_0, src_reg); - else - emit_mov_imm32(&prog, is64, BPF_REG_0, imm32); - - if (is64) - EMIT1(add_1mod(0x48, AUX_REG)); - else if (is_ereg(AUX_REG)) - EMIT1(add_1mod(0x40, AUX_REG)); - /* mul(q) r11 */ - EMIT2(0xF7, add_1reg(0xE0, AUX_REG)); - - if (dst_reg != BPF_REG_3) - EMIT1(0x5A); /* pop rdx */ - if (dst_reg != BPF_REG_0) { - /* mov dst_reg, rax */ - EMIT_mov(dst_reg, BPF_REG_0); - EMIT1(0x58); /* pop rax */ - } + /* imul dst_reg, src_reg */ + EMIT3(0x0F, 0xAF, add_2reg(0xC0, src_reg, dst_reg)); break; - } + /* Shifts */ case BPF_ALU | BPF_LSH | BPF_K: case BPF_ALU | BPF_RSH | BPF_K: |