linux-kernel - [PATCH AUTOSEL 4.9 22/24] nfp: bpf: fix ALU32 high bits clearance bug

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Message-Id: <20190313191647.160171-22-sashal@kernel.org>
Date:   Wed, 13 Mar 2019 15:16:45 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jiong Wang <jiong.wang@...ronome.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>, oss-drivers@...ronome.com,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 22/24] nfp: bpf: fix ALU32 high bits clearance bug

From: Jiong Wang <jiong.wang@...ronome.com>

[ Upstream commit f036ebd9bfbe1e91a3d855e85e05fc5ff156b641 ]

NFP BPF JIT compiler is doing a couple of small optimizations when jitting
ALU imm instructions, some of these optimizations could save code-gen, for
example:

  A & -1 =  A
  A |  0 =  A
  A ^  0 =  A

However, for ALU32, high 32-bit of the 64-bit register should still be
cleared according to ISA semantics.

Fixes: cd7df56ed3e6 ("nfp: add BPF to NFP code translator")
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../net/ethernet/netronome/nfp/nfp_bpf_jit.c    | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_bpf_jit.c b/drivers/net/ethernet/netronome/nfp/nfp_bpf_jit.c
index 6bfcd6eb74ca..73087770d72f 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_bpf_jit.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_bpf_jit.c
@@ -756,15 +756,10 @@ wrp_alu64_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
 
 static int
 wrp_alu32_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
-	      enum alu_op alu_op, bool skip)
+	      enum alu_op alu_op)
 {
 	const struct bpf_insn *insn = &meta->insn;
 
-	if (skip) {
-		meta->skip = true;
-		return 0;
-	}
-
 	wrp_alu_imm(nfp_prog, insn->dst_reg * 2, alu_op, insn->imm);
 	wrp_immed(nfp_prog, reg_both(insn->dst_reg * 2 + 1), 0);
 
@@ -1017,7 +1012,7 @@ static int xor_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int xor_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_XOR, !meta->insn.imm);
+	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_XOR);
 }
 
 static int and_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
@@ -1027,7 +1022,7 @@ static int and_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int and_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_AND, !~meta->insn.imm);
+	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_AND);
 }
 
 static int or_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
@@ -1037,7 +1032,7 @@ static int or_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int or_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_OR, !meta->insn.imm);
+	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_OR);
 }
 
 static int add_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
@@ -1047,7 +1042,7 @@ static int add_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int add_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_ADD, !meta->insn.imm);
+	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_ADD);
 }
 
 static int sub_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
@@ -1057,7 +1052,7 @@ static int sub_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 
 static int sub_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
-	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_SUB, !meta->insn.imm);
+	return wrp_alu32_imm(nfp_prog, meta, ALU_OP_SUB);
 }
 
 static int shl_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
-- 
2.19.1