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From: Brendan Jackman <jackmanb@google.com>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>, Yonghong Song <yhs@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	KP Singh <kpsingh@chromium.org>,
	Florent Revest <revest@chromium.org>,
	linux-kernel@vger.kernel.org, Jann Horn <jannh@google.com>,
	Brendan Jackman <jackmanb@google.com>
Subject: [PATCH bpf-next v4 08/11] bpf: Pull out a macro for interpreting atomic ALU operations
Date: Mon,  7 Dec 2020 16:07:31 +0000	[thread overview]
Message-ID: <20201207160734.2345502-9-jackmanb@google.com> (raw)
In-Reply-To: <20201207160734.2345502-1-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 28f960bc2e30..1d9e5dcde03a 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 *)(s64) (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 *)(s64) (DST + insn->off));
-			break;
+		ATOMIC_ALU_OP(BPF_ADD, add)
+#undef ATOMIC_ALU_OP
+
 		case BPF_XCHG:
-			SRC = (u64) atomic64_xchg(
-				(atomic64_t *)(u64) (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 *)(u64) (DST + insn->off),
+					(u64) SRC);
 			break;
 		case BPF_CMPXCHG:
-			BPF_R0 = (u64) atomic64_cmpxchg(
-				(atomic64_t *)(u64) (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 *)(u64) (DST + insn->off),
+					(u64) BPF_R0, (u64) SRC);
 			break;
+
 		default:
 			goto default_label;
 		}
-- 
2.29.2.576.ga3fc446d84-goog


  parent reply	other threads:[~2020-12-07 16:16 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-07 16:07 [PATCH bpf-next v4 00/11] Atomics for eBPF Brendan Jackman
2020-12-07 16:07 ` [PATCH bpf-next v4 01/11] bpf: x86: Factor out emission of ModR/M for *(reg + off) Brendan Jackman
2020-12-07 21:04   ` John Fastabend
2020-12-07 16:07 ` [PATCH bpf-next v4 02/11] bpf: x86: Factor out emission of REX byte Brendan Jackman
2020-12-07 21:07   ` John Fastabend
2020-12-07 16:07 ` [PATCH bpf-next v4 03/11] bpf: x86: Factor out a lookup table for some ALU opcodes Brendan Jackman
2020-12-07 21:08   ` John Fastabend
2020-12-07 16:07 ` [PATCH bpf-next v4 04/11] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm Brendan Jackman
2020-12-07 21:56   ` John Fastabend
2020-12-08  9:26     ` Brendan Jackman
2020-12-09  5:40       ` John Fastabend
2020-12-07 16:07 ` [PATCH bpf-next v4 05/11] bpf: Move BPF_STX reserved field check into BPF_STX verifier code Brendan Jackman
2020-12-08  1:35   ` Yonghong Song
2020-12-08  5:13   ` John Fastabend
2020-12-07 16:07 ` [PATCH bpf-next v4 06/11] bpf: Add BPF_FETCH field / create atomic_fetch_add instruction Brendan Jackman
2020-12-08  1:41   ` Yonghong Song
2020-12-08  9:31     ` Brendan Jackman
2020-12-08  5:31   ` John Fastabend
2020-12-08  9:59     ` Brendan Jackman
2020-12-07 16:07 ` [PATCH bpf-next v4 07/11] bpf: Add instructions for atomic_[cmp]xchg Brendan Jackman
2020-12-08  1:44   ` Yonghong Song
2020-12-08  6:37   ` John Fastabend
2020-12-14 15:39     ` Brendan Jackman
2020-12-08  6:42   ` John Fastabend
2020-12-07 16:07 ` Brendan Jackman [this message]
2020-12-07 16:07 ` [PATCH bpf-next v4 09/11] bpf: Add bitwise atomic instructions Brendan Jackman
2020-12-08  1:47   ` Yonghong Song
2020-12-10  0:22   ` kernel test robot
2020-12-07 16:07 ` [PATCH bpf-next v4 10/11] bpf: Add tests for new BPF atomic operations Brendan Jackman
2020-12-08  3:18   ` Yonghong Song
2020-12-08 12:41     ` Brendan Jackman
2020-12-08 16:38       ` Yonghong Song
2020-12-08 16:59         ` Brendan Jackman
2020-12-08 18:15           ` Yonghong Song
2020-12-15 11:12             ` Brendan Jackman
2020-12-16  7:18               ` Yonghong Song
2020-12-16 11:51                 ` Brendan Jackman
2020-12-16 20:00                   ` Yonghong Song
2020-12-07 16:07 ` [PATCH bpf-next v4 11/11] bpf: Document new atomic instructions Brendan Jackman
2020-12-08  3:25   ` Yonghong Song

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