Le 05/10/2021 à 22:25, Naveen N. Rao a écrit :
We aren't handling subtraction involving an immediate value of
0x80000000 properly. Fix the same.
Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
---
Changelog:
- Split up BPF_ADD and BPF_SUB cases per Christophe's comments
arch/powerpc/net/bpf_jit_comp64.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index d67f6d62e2e1ff..6626e6c17d4ed2 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -330,18 +330,25 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
EMIT(PPC_RAW_SUB(dst_reg, dst_reg, src_reg));
goto bpf_alu32_trunc;
case BPF_ALU | BPF_ADD | BPF_K: /* (u32) dst += (u32) imm */
- case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
+ if (!imm) {
+ goto bpf_alu32_trunc;
+ } else if (imm >= -32768 && imm < 32768) {
+ EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
+ } else {
+ PPC_LI32(b2p[TMP_REG_1], imm);
+ EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
+ }
+ goto bpf_alu32_trunc;
+ case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
- if (BPF_OP(code) == BPF_SUB)
- imm = -imm;
- if (imm) {
- if (imm >= -32768 && imm < 32768)
- EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
- else {
- PPC_LI32(b2p[TMP_REG_1], imm);
- EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
- }
+ if (!imm) {
+ goto bpf_alu32_trunc;
+ } else if (imm > -32768 && imm < 32768) {
Why do you exclude imm == 32768 ?
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
+ EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(-imm)));
+ } else {
+ PPC_LI32(b2p[TMP_REG_1], imm);
+ EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
}
goto bpf_alu32_trunc;
case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */
