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| author | Brendan Jackman <jackmanb@google.com> | 2021-01-14 18:17:46 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-01-14 18:34:29 -0800 |
| commit | 5ca419f2864a2c60940dcf4bbaeb69546200e36f (patch) | |
| tree | edd181e67503cb404dfa55cfaae6d757db3e22b6 /arch/x86/net | |
| parent | c5bcb5eb4db632280b4123135d583a7bc8caea3e (diff) | |
| download | linux-stable-5ca419f2864a2c60940dcf4bbaeb69546200e36f.tar.gz linux-stable-5ca419f2864a2c60940dcf4bbaeb69546200e36f.tar.bz2 linux-stable-5ca419f2864a2c60940dcf4bbaeb69546200e36f.zip | |
bpf: Add BPF_FETCH field / create atomic_fetch_add instruction
The BPF_FETCH field can be set in bpf_insn.imm, for BPF_ATOMIC
instructions, in order to have the previous value of the
atomically-modified memory location loaded into the src register
after an atomic op is carried out.
Suggested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-7-jackmanb@google.com
Diffstat (limited to 'arch/x86/net')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index b1829a534da1..eea7d8b0bb12 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -811,6 +811,10 @@ static int emit_atomic(u8 **pprog, u8 atomic_op, /* lock *(u32/u64*)(dst_reg + off) <op>= src_reg */ EMIT1(simple_alu_opcodes[atomic_op]); break; + case BPF_ADD | BPF_FETCH: + /* src_reg = atomic_fetch_add(dst_reg + off, src_reg); */ + EMIT2(0x0F, 0xC1); + break; default: pr_err("bpf_jit: unknown atomic opcode %02x\n", atomic_op); return -EFAULT; |