The JITs should not depend on the verifier for zero extending the upper
32 bits of the destination register when loading a byte, half-word, or
word.
A following patch will make the verifier stop patching zext instructions
after LDX.
Signed-off-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
---
arch/powerpc/net/bpf_jit_comp32.c | 25 ++++++++-----------------
1 file changed, 8 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 7f91ea064c08..0a952a2cfaac 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -936,14 +936,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
PPC_BCC_SHORT(COND_GT, (ctx->idx + 4) * 4);
EMIT(PPC_RAW_LI(dst_reg, 0));
/*
- * For BPF_DW case, "li reg_h,0" would be needed when
- * !fp->aux->verifier_zext. Emit NOP otherwise.
+ * For BPF_DW case, "li reg_h,0" would be needed emit NOP otherwise.
*
* Note that "li reg_h,0" is emitted for BPF_B/H/W case,
* if necessary. So, jump there insted of emitting an
* additional "li reg_h,0" instruction.
*/
- if (size == BPF_DW && !fp->aux->verifier_zext)
+ if (size == BPF_DW)
EMIT(PPC_RAW_LI(dst_reg_h, 0));
else
EMIT(PPC_RAW_NOP());
@@ -974,7 +973,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
break;
}
- if (size != BPF_DW && !fp->aux->verifier_zext)
+ if (size != BPF_DW)
EMIT(PPC_RAW_LI(dst_reg_h, 0));
if (BPF_MODE(code) == BPF_PROBE_MEM) {
@@ -982,20 +981,12 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
int jmp_off = 4;
/*
- * In case of BPF_DW, two lwz instructions are emitted, one
- * for higher 32-bit and another for lower 32-bit. So, set
- * ex->insn to the first of the two and jump over both
- * instructions in fixup.
- *
- * Similarly, with !verifier_zext, two instructions are
- * emitted for BPF_B/H/W case. So, set ex->insn to the
- * instruction that could fault and skip over both
- * instructions.
+ * Two instructions are emitted for LDX.
+ * So, set ex->insn to the instruction that could fault and skip
+ * over both instructions.
*/
- if (size == BPF_DW || !fp->aux->verifier_zext) {
- insn_idx -= 1;
- jmp_off += 4;
- }
+ insn_idx -= 1;
+ jmp_off += 4;
ret = bpf_add_extable_entry(fp, image, pass, ctx, insn_idx,
jmp_off, dst_reg);
--
2.39.2
