From: Brendan Jackman <jackmanb@google.com>
To: bpf@vger.kernel.org
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii.nakryiko@gmail.com>,
"KP Singh" <kpsingh@chromium.org>,
"Florent Revest" <revest@chromium.org>,
linux-kernel@vger.kernel.org,
"Björn Töpel" <bjorn.topel@gmail.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"Yonghong Song" <yhs@fb.com>,
"Brendan Jackman" <jackmanb@google.com>
Subject: [PATCH bpf-next v7 03/11] bpf: x86: Factor out a lookup table for some ALU opcodes
Date: Thu, 14 Jan 2021 18:17:43 +0000 [thread overview]
Message-ID: <20210114181751.768687-4-jackmanb@google.com> (raw)
In-Reply-To: <20210114181751.768687-1-jackmanb@google.com>
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 <jackmanb@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.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)
--
2.30.0.284.gd98b1dd5eaa7-goog
next prev parent reply other threads:[~2021-01-14 18:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-14 18:17 [PATCH bpf-next v7 00/11] Atomics for eBPF Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 01/11] bpf: x86: Factor out emission of ModR/M for *(reg + off) Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 02/11] bpf: x86: Factor out emission of REX byte Brendan Jackman
2021-01-14 18:17 ` Brendan Jackman [this message]
2021-01-14 18:17 ` [PATCH bpf-next v7 04/11] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 05/11] bpf: Move BPF_STX reserved field check into BPF_STX verifier code Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 06/11] bpf: Add BPF_FETCH field / create atomic_fetch_add instruction Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 07/11] bpf: Add instructions for atomic_[cmp]xchg Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 08/11] bpf: Pull out a macro for interpreting atomic ALU operations Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 09/11] bpf: Add bitwise atomic instructions Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 10/11] bpf: Add tests for new BPF atomic operations Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 11/11] bpf: Document new atomic instructions Brendan Jackman
2021-01-15 3:20 ` [PATCH bpf-next v7 00/11] Atomics for eBPF patchwork-bot+netdevbpf
2021-01-15 3:23 ` Alexei Starovoitov
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