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From:   Jianlin Lv <Jianlin.Lv@arm.com>
To:     bpf@vger.kernel.org
Cc:     kuba@kernel.org, simon.horman@netronome.com, davem@davemloft.net,
        ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
        kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
        john.fastabend@gmail.com, kpsingh@kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        oss-drivers@netronome.com, linux-api@vger.kernel.org,
        Jianlin.Lv@arm.com, iecedge@gmail.com
Subject: [PATCH bpf-next] bpf: Simplify expression for identify bpf mem type
Date:   Wed, 17 Mar 2021 20:51:47 +0800
Message-Id: <20210317125147.2159512-1-Jianlin.Lv@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Added BPF_SIZE_MASK macro as mask of size modifier that help to reduce
the evaluation of expressions in if statements,
and remove BPF_SIZE_MASK in netronome driver.

Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/main.h |  2 --
 include/uapi/linux/bpf.h                      |  1 +
 kernel/bpf/verifier.c                         | 12 ++++--------
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index d0e17eebddd9..8b1c2509ce46 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -346,8 +346,6 @@ struct nfp_insn_meta {
 	struct list_head l;
 };
 
-#define BPF_SIZE_MASK	0x18
-
 static inline u8 mbpf_class(const struct nfp_insn_meta *meta)
 {
 	return BPF_CLASS(meta->insn.code);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2d3036e292a9..5d77675e7112 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -21,6 +21,7 @@
 #define BPF_DW		0x18	/* double word (64-bit) */
 #define BPF_ATOMIC	0xc0	/* atomic memory ops - op type in immediate */
 #define BPF_XADD	0xc0	/* exclusive add - legacy name */
+#define BPF_SIZE_MASK	0x18    /* mask of size modifier */
 
 /* alu/jmp fields */
 #define BPF_MOV		0xb0	/* mov reg to reg */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f9096b049cd6..9755bb4d7de4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11384,15 +11384,11 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 	for (i = 0; i < insn_cnt; i++, insn++) {
 		bpf_convert_ctx_access_t convert_ctx_access;
 
-		if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
-		    insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
-		    insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
-		    insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
+		/* opcode: BPF_MEM | <size> | BPF_LDX */
+		if ((insn->code & ~BPF_SIZE_MASK) == (BPF_LDX | BPF_MEM))
 			type = BPF_READ;
-		else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
-			 insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
-			 insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
-			 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
+		/* opcode: BPF_MEM | <size> | BPF_STX */
+		else if ((insn->code & ~BPF_SIZE_MASK) == (BPF_STX | BPF_MEM))
 			type = BPF_WRITE;
 		else
 			continue;
-- 
2.25.1