[bpf,2/2] nfp: bpf: fix ALU32 high bits clearance bug
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Message ID 1550874964-16769-3-git-send-email-jiong.wang@netronome.com
State Accepted
Delegated to: BPF Maintainers
Headers show
Series
  • nfp: bpf: fix two ALU32 code-gen bugs
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Commit Message

Jiong Wang Feb. 22, 2019, 10:36 p.m. UTC
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@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

Patch
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diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index a096965..0a868c8 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -1291,15 +1291,10 @@  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);
 
@@ -2309,7 +2304,7 @@  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)
@@ -2319,7 +2314,7 @@  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)
@@ -2329,7 +2324,7 @@  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)
@@ -2339,7 +2334,7 @@  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)
@@ -2349,7 +2344,7 @@  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 mul_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)