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

From: Sasha Levin
Date: Wed Mar 13 2019 - 15:18:00 EST


From: Jiong Wang <jiong.wang@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: Jiong Wang <jiong.wang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
.../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