From: Xiao Wang <xiao.w.wang@intel.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, luke.r.nels@gmail.com, xi.wang@gmail.com,
bjorn@kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org,
yonghong.song@linux.dev, john.fastabend@gmail.com,
kpsingh@kernel.org, sdf@google.com, haoluo@google.com,
jolsa@kernel.org, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
pulehui@huawei.com, haicheng.li@intel.com,
Xiao Wang <xiao.w.wang@intel.com>
Subject: [PATCH] riscv, bpf: try RVC for reg move within BPF_CMPXCHG JIT
Date: Sun, 19 May 2024 13:05:07 +0800 [thread overview]
Message-ID: <20240519050507.2217791-1-xiao.w.wang@intel.com> (raw)
We could try to emit compressed insn for reg move operation during CMPXCHG
JIT, the instruction compression has no impact on the jump offsets of
following forward and backward jump instructions.
Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
---
arch/riscv/net/bpf_jit_comp64.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index aac190085472..c134aaec4295 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -531,8 +531,10 @@ static void emit_atomic(u8 rd, u8 rs, s16 off, s32 imm, bool is64,
/* r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg); */
case BPF_CMPXCHG:
r0 = bpf_to_rv_reg(BPF_REG_0, ctx);
- emit(is64 ? rv_addi(RV_REG_T2, r0, 0) :
- rv_addiw(RV_REG_T2, r0, 0), ctx);
+ if (is64)
+ emit_mv(RV_REG_T2, r0, ctx);
+ else
+ emit_addiw(RV_REG_T2, r0, 0, ctx);
emit(is64 ? rv_lr_d(r0, 0, rd, 0, 0) :
rv_lr_w(r0, 0, rd, 0, 0), ctx);
jmp_offset = ninsns_rvoff(8);
--
2.25.1
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next reply other threads:[~2024-05-19 5:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-19 5:05 Xiao Wang [this message]
2024-05-21 16:35 ` [PATCH] riscv, bpf: try RVC for reg move within BPF_CMPXCHG JIT Björn Töpel
2024-05-24 15:50 ` patchwork-bot+netdevbpf
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