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authorDaniel Borkmann <daniel@iogearbox.net>2018-02-24 03:08:01 +0300
committerAlexei Starovoitov <ast@kernel.org>2018-02-24 09:50:00 +0300
commit4c38e2f386b4fc5fd95d1203c74819948e2e903d (patch)
tree26e9b52c57d79f91206e09624e5eaaa360275f1f /arch/x86/net/bpf_jit_comp.c
parentd806a0cf2a1ddb97c91d902ef1c8219e1e2b2c4c (diff)
downloadlinux-4c38e2f386b4fc5fd95d1203c74819948e2e903d.tar.xz
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>
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
-rw-r--r--arch/x86/net/bpf_jit_comp.c43
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: