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From:   Puranjay Mohan <puranjay12@gmail.com>
To:     Alexei Starovoitov <ast@kernel.org>,
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Cc:     puranjay12@gmail.com
Subject: [PATCH bpf-next 1/6] bpf, riscv32: Always zero extend for LDX with B/W/H
Date:   Tue, 12 Sep 2023 22:46:49 +0000
Message-Id: <20230912224654.6556-2-puranjay12@gmail.com>
In-Reply-To: <20230912224654.6556-1-puranjay12@gmail.com>
References: <20230912224654.6556-1-puranjay12@gmail.com>
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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@gmail.com>
---
 arch/riscv/net/bpf_jit_comp32.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp32.c b/arch/riscv/net/bpf_jit_comp32.c
index 529a83b85c1c..8f8255519ba1 100644
--- a/arch/riscv/net/bpf_jit_comp32.c
+++ b/arch/riscv/net/bpf_jit_comp32.c
@@ -847,18 +847,15 @@ static int emit_load_r64(const s8 *dst, const s8 *src, s16 off,
 	switch (size) {
 	case BPF_B:
 		emit(rv_lbu(lo(rd), 0, RV_REG_T0), ctx);
-		if (!ctx->prog->aux->verifier_zext)
-			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
+		emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
 		break;
 	case BPF_H:
 		emit(rv_lhu(lo(rd), 0, RV_REG_T0), ctx);
-		if (!ctx->prog->aux->verifier_zext)
-			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
+		emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
 		break;
 	case BPF_W:
 		emit(rv_lw(lo(rd), 0, RV_REG_T0), ctx);
-		if (!ctx->prog->aux->verifier_zext)
-			emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
+		emit(rv_addi(hi(rd), RV_REG_ZERO, 0), ctx);
 		break;
 	case BPF_DW:
 		emit(rv_lw(lo(rd), 0, RV_REG_T0), ctx);
-- 
2.39.2