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 08/11] bpf: Pull out a macro for interpreting atomic ALU operations
Date: Thu, 14 Jan 2021 18:17:48 +0000 [thread overview]
Message-ID: <20210114181751.768687-9-jackmanb@google.com> (raw)
In-Reply-To: <20210114181751.768687-1-jackmanb@google.com>
Since the atomic operations that are added in subsequent commits are
all isomorphic with BPF_ADD, pull out a macro to avoid the
interpreter becoming dominated by lines of atomic-related code.
Note that this sacrificies interpreter performance (combining
STX_ATOMIC_W and STX_ATOMIC_DW into single switch case means that we
need an extra conditional branch to differentiate them) in favour of
compact and (relatively!) simple C code.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
kernel/bpf/core.c | 80 +++++++++++++++++++++++------------------------
1 file changed, 39 insertions(+), 41 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 4df6daba43ef..8669e685825f 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1618,55 +1618,53 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack)
LDX_PROBE(DW, 8)
#undef LDX_PROBE
- STX_ATOMIC_W:
- switch (IMM) {
- case BPF_ADD:
- /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */
- atomic_add((u32) SRC, (atomic_t *)(unsigned long)
- (DST + insn->off));
- break;
- case BPF_ADD | BPF_FETCH:
- SRC = (u32) atomic_fetch_add(
- (u32) SRC,
- (atomic_t *)(unsigned long) (DST + insn->off));
- break;
- case BPF_XCHG:
- SRC = (u32) atomic_xchg(
- (atomic_t *)(unsigned long) (DST + insn->off),
- (u32) SRC);
- break;
- case BPF_CMPXCHG:
- BPF_R0 = (u32) atomic_cmpxchg(
- (atomic_t *)(unsigned long) (DST + insn->off),
- (u32) BPF_R0, (u32) SRC);
+#define ATOMIC_ALU_OP(BOP, KOP) \
+ case BOP: \
+ if (BPF_SIZE(insn->code) == BPF_W) \
+ atomic_##KOP((u32) SRC, (atomic_t *)(unsigned long) \
+ (DST + insn->off)); \
+ else \
+ atomic64_##KOP((u64) SRC, (atomic64_t *)(unsigned long) \
+ (DST + insn->off)); \
+ break; \
+ case BOP | BPF_FETCH: \
+ if (BPF_SIZE(insn->code) == BPF_W) \
+ SRC = (u32) atomic_fetch_##KOP( \
+ (u32) SRC, \
+ (atomic_t *)(unsigned long) (DST + insn->off)); \
+ else \
+ SRC = (u64) atomic64_fetch_##KOP( \
+ (u64) SRC, \
+ (atomic64_t *)(unsigned long) (DST + insn->off)); \
break;
- default:
- goto default_label;
- }
- CONT;
STX_ATOMIC_DW:
+ STX_ATOMIC_W:
switch (IMM) {
- case BPF_ADD:
- /* lock xadd *(u64 *)(dst_reg + off16) += src_reg */
- atomic64_add((u64) SRC, (atomic64_t *)(unsigned long)
- (DST + insn->off));
- break;
- case BPF_ADD | BPF_FETCH:
- SRC = (u64) atomic64_fetch_add(
- (u64) SRC,
- (atomic64_t *)(unsigned long) (DST + insn->off));
- break;
+ ATOMIC_ALU_OP(BPF_ADD, add)
+#undef ATOMIC_ALU_OP
+
case BPF_XCHG:
- SRC = (u64) atomic64_xchg(
- (atomic64_t *)(unsigned long) (DST + insn->off),
- (u64) SRC);
+ if (BPF_SIZE(insn->code) == BPF_W)
+ SRC = (u32) atomic_xchg(
+ (atomic_t *)(unsigned long) (DST + insn->off),
+ (u32) SRC);
+ else
+ SRC = (u64) atomic64_xchg(
+ (atomic64_t *)(unsigned long) (DST + insn->off),
+ (u64) SRC);
break;
case BPF_CMPXCHG:
- BPF_R0 = (u64) atomic64_cmpxchg(
- (atomic64_t *)(unsigned long) (DST + insn->off),
- (u64) BPF_R0, (u64) SRC);
+ if (BPF_SIZE(insn->code) == BPF_W)
+ BPF_R0 = (u32) atomic_cmpxchg(
+ (atomic_t *)(unsigned long) (DST + insn->off),
+ (u32) BPF_R0, (u32) SRC);
+ else
+ BPF_R0 = (u64) atomic64_cmpxchg(
+ (atomic64_t *)(unsigned long) (DST + insn->off),
+ (u64) BPF_R0, (u64) SRC);
break;
+
default:
goto default_label;
}
--
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 ` [PATCH bpf-next v7 03/11] bpf: x86: Factor out a lookup table for some ALU opcodes Brendan Jackman
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 ` Brendan Jackman [this message]
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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