From b6ec79518ef0c84d1ed0f76b8af9592a75eb29b6 Mon Sep 17 00:00:00 2001
From: Hou Tao <houtao1@huawei.com>
Date: Thu, 27 Jan 2022 16:32:40 +0800
Subject: [PATCH] bpf, x86: Remove unnecessary handling of BPF_SUB atomic op
According to the LLVM commit (https://reviews.llvm.org/D72184),
sync_fetch_and_sub() is implemented as a negation followed by
sync_fetch_and_add(), so there will be no BPF_SUB op, thus just
remove it. BPF_SUB is also rejected by the verifier anyway.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20220127083240.1425481-1-houtao1@huawei.com
---
arch/x86/net/bpf_jit_comp.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 2b1e266ff95c3..36f6fc3e6e690 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -787,7 +787,6 @@ static int emit_atomic(u8 **pprog, u8 atomic_op,
/* emit opcode */
switch (atomic_op) {
case BPF_ADD:
- case BPF_SUB:
case BPF_AND:
case BPF_OR:
case BPF_XOR:
--
2.30.2