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bpf, x64: save few bytes when mul is in alu32

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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>
This commit is contained in:
Daniel Borkmann 2018-02-24 01:08:01 +01:00 committed by Alexei Starovoitov
parent d806a0cf2a
commit 4c38e2f386
1 changed files with 28 additions and 15 deletions
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43
arch/x86/net/bpf_jit_comp.c
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@ -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: