From: Qinxin Xia <xiaqinxin@huawei.com>
To: <catalin.marinas@arm.com>, <will@kernel.org>,
<anshuman.khandual@arm.com>, <BenNiu@meta.com>,
<robin.murphy@arm.com>, <xiqi2@huawei.com>,
<xiaqinxin@huawei.com>
Cc: <linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <linuxarm@huawei.com>,
<wangzhou1@hisilicon.com>, <sunnanyong@huawei.com>,
<prime.zeng@hisilicon.com>
Subject: [PATCH] arm64: uaccess: Optimize copy_to/from_user with LSUI extension
Date: Wed, 5 Aug 2026 11:52:51 +0800 [thread overview]
Message-ID: <20260805035251.2813306-1-xiaqinxin@huawei.com> (raw)
Add support for the ARMv9.6/LSUI (Load/Store Unprivileged Immediate)
extension to optimize copy_from_user operations. The implementation
uses the alternative mechanism to select between the standard unprivileged
load-pair sequence and the new ldtp/sttp instruction at runtime based on
hardware capability.
Co-developed-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Qinxin Xia <xiaqinxin@huawei.com>
---
arch/arm64/include/asm/asm-uaccess.h | 6 ++++++
arch/arm64/lib/copy_from_user.S | 11 +++++++++++
arch/arm64/lib/copy_to_user.S | 11 +++++++++++
3 files changed, 28 insertions(+)
diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 12aa6a283249..4c1b94b275e9 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -94,4 +94,10 @@ alternative_else_nop_endif
_asm_extable_uaccess 8888b, \l;
.endm
+
+ .macro user_ldst_pair l, inst, reg1, reg2, addr, post_inc
+8888: \inst \reg1, \reg2, [\addr], \post_inc;
+
+ _asm_extable_uaccess 8888b, \l;
+ .endm
#endif
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 400057d607ec..f561a9c07345 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -45,7 +45,18 @@
.endm
.macro ldp1 reg1, reg2, ptr, val
+#ifdef CONFIG_ARM64_LSUI
+ alternative_if_not ARM64_HAS_LSUI
+ user_ldp 9997f, \reg1, \reg2, \ptr, \val
+ alternative_else
+ .arch_extension lsui
+ user_ldst_pair 9997f, ldtp, \reg1, \reg2, \ptr, \val
+ nop
+ nop
+ alternative_endif
+#else
user_ldp 9997f, \reg1, \reg2, \ptr, \val
+#endif
.endm
.macro stp1 reg1, reg2, ptr, val
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 819f2e3fc7a9..a77dd153566f 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -48,7 +48,18 @@
.endm
.macro stp1 reg1, reg2, ptr, val
+#ifdef CONFIG_ARM64_LSUI
+ alternative_if_not ARM64_HAS_LSUI
+ user_stp 9997f, \reg1, \reg2, \ptr, \val
+ alternative_else
+ .arch_extension lsui
+ user_ldst_pair 9997f, sttp, \reg1, \reg2, \ptr, \val
+ nop
+ nop
+ alternative_endif
+#else
user_stp 9997f, \reg1, \reg2, \ptr, \val
+#endif
.endm
.macro cpy1 dst, src, count
--
2.33.0
reply other threads:[~2026-08-05 3:53 UTC|newest]
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