diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-02-24 01:08:01 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2018-02-23 22:50:00 -0800 |
| commit | 4c38e2f386b4fc5fd95d1203c74819948e2e903d (patch) | |
| tree | 26e9b52c57d79f91206e09624e5eaaa360275f1f | |
| parent | d806a0cf2a1ddb97c91d902ef1c8219e1e2b2c4c (diff) | |
| download | linux-4c38e2f386b4fc5fd95d1203c74819948e2e903d.tar.bz2 | |
bpf, x64: save few bytes when mul is in alu32
Add a generic emit_mov_reg() helper in order to reuse it in BPF
multiplication to load the src into rax, we can save a few bytes
in alu32 while doing so.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 43 |
1 files changed, 28 insertions, 15 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 9895ca383023..5b8fc1326aa1 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -422,6 +422,24 @@ static void emit_mov_imm64(u8 **pprog, u32 dst_reg, *pprog = prog; } +static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (is64) { + /* mov dst, src */ + EMIT_mov(dst_reg, src_reg); + } else { + /* mov32 dst, src */ + if (is_ereg(dst_reg) || is_ereg(src_reg)) + EMIT1(add_2mod(0x40, dst_reg, src_reg)); + EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg)); + } + + *pprog = prog; +} + static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, int oldproglen, struct jit_context *ctx) { @@ -480,16 +498,11 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); break; - /* mov dst, src */ case BPF_ALU64 | BPF_MOV | BPF_X: - EMIT_mov(dst_reg, src_reg); - break; - - /* mov32 dst, src */ case BPF_ALU | BPF_MOV | BPF_X: - if (is_ereg(dst_reg) || is_ereg(src_reg)) - EMIT1(add_2mod(0x40, dst_reg, src_reg)); - EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg)); + emit_mov_reg(&prog, + BPF_CLASS(insn->code) == BPF_ALU64, + dst_reg, src_reg); break; /* neg dst */ @@ -615,6 +628,9 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 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 (dst_reg != BPF_REG_0) EMIT1(0x50); /* push rax */ if (dst_reg != BPF_REG_3) @@ -624,14 +640,11 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, EMIT_mov(AUX_REG, dst_reg); if (BPF_SRC(insn->code) == BPF_X) - /* mov rax, src_reg */ - EMIT_mov(BPF_REG_0, src_reg); + emit_mov_reg(&prog, is64, BPF_REG_0, src_reg); else - /* mov rax, imm32 */ - emit_mov_imm32(&prog, true, - BPF_REG_0, imm32); + emit_mov_imm32(&prog, is64, BPF_REG_0, imm32); - if (BPF_CLASS(insn->code) == BPF_ALU64) + if (is64) EMIT1(add_1mod(0x48, AUX_REG)); else if (is_ereg(AUX_REG)) EMIT1(add_1mod(0x40, AUX_REG)); @@ -646,7 +659,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, EMIT1(0x58); /* pop rax */ } break; - + } /* shifts */ case BPF_ALU | BPF_LSH | BPF_K: case BPF_ALU | BPF_RSH | BPF_K: |