From: Daniel Borkmann <daniel@iogearbox.net>
To: ast@kernel.org
Cc: netdev@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>
Subject: [PATCH bpf-next 01/13] bpf: xor of a/x in cbpf can be done in 32 bit alu
Date: Fri, 26 Jan 2018 23:33:36 +0100 [thread overview]
Message-ID: <20180126223348.11250-2-daniel@iogearbox.net> (raw)
In-Reply-To: <20180126223348.11250-1-daniel@iogearbox.net>
Very minor optimization; saves 1 byte per program in x86_64
JIT in cBPF prologue.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---
net/core/filter.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 18da42a..cba2f73 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -401,8 +401,8 @@ static int bpf_convert_filter(struct sock_filter *prog, int len,
/* Classic BPF expects A and X to be reset first. These need
* to be guaranteed to be the first two instructions.
*/
- *new_insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_A, BPF_REG_A);
- *new_insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_X, BPF_REG_X);
+ *new_insn++ = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_A);
+ *new_insn++ = BPF_ALU32_REG(BPF_XOR, BPF_REG_X, BPF_REG_X);
/* All programs must keep CTX in callee saved BPF_REG_CTX.
* In eBPF case it's done by the compiler, here we need to
--
2.9.5
next prev parent reply other threads:[~2018-01-26 22:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-26 22:33 [PATCH bpf-next 00/13] BPF improvements and fixes Daniel Borkmann
2018-01-26 22:33 ` Daniel Borkmann [this message]
2018-01-28 18:58 ` [PATCH bpf-next 01/13] bpf: xor of a/x in cbpf can be done Naveen N. Rao
2018-01-28 20:51 ` Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 02/13] bpf: improve dead code sanitizing Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 03/13] bpf: make unknown opcode handling more robust Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 04/13] bpf: fix subprog verifier bypass by div/mod by 0 exception Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 05/13] bpf, x86_64: remove obsolete exception handling from div/mod Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 06/13] bpf, arm64: " Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 07/13] bpf, s390x: " Daniel Borkmann
2018-01-29 14:33 ` Michael Holzheu
2018-01-29 15:52 ` Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 08/13] bpf, ppc64: " Daniel Borkmann
2018-01-28 18:52 ` Naveen N. Rao
2018-01-26 22:33 ` [PATCH bpf-next 09/13] bpf, sparc64: " Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 10/13] bpf, mips64: " Daniel Borkmann
2018-01-26 22:39 ` David Daney
2018-01-26 22:33 ` [PATCH bpf-next 11/13] bpf, mips64: remove unneeded zero check from div/mod with k Daniel Borkmann
2018-01-26 22:36 ` David Daney
2018-01-26 22:33 ` [PATCH bpf-next 12/13] bpf, arm: remove obsolete exception handling from div/mod Daniel Borkmann
2018-01-26 22:33 ` [PATCH bpf-next 13/13] bpf: add further test cases around div/mod and others Daniel Borkmann
2018-01-27 0:48 ` [PATCH bpf-next 00/13] BPF improvements and fixes Alexei Starovoitov
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