linux-kernel - [PATCH v3 18/21] arm64/xorblocks: Switch to 'ksimd' scoped guard API

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Message-ID: <20251008154533.3089255-41-ardb+git@google.com>
Date: Wed,  8 Oct 2025 17:45:52 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, 
	herbert@...dor.apana.org.au, ebiggers@...nel.org, 
	Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH v3 18/21] arm64/xorblocks:  Switch to 'ksimd' scoped guard API

From: Ard Biesheuvel <ardb@...nel.org>

Switch to the more abstract 'scoped_ksimd()' API, which will be modified
in a future patch to transparently allocate a kernel mode FP/SIMD state
buffer on the stack, so that kernel mode FP/SIMD code remains
preemptible in principe, but without the memory overhead that adds 528
bytes to the size of struct task_struct.

Reviewed-by: Eric Biggers <ebiggers@...nel.org>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/arm64/include/asm/xor.h | 22 ++++++++------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/xor.h b/arch/arm64/include/asm/xor.h
index befcd8a7abc9..c38e3d017a79 100644
--- a/arch/arm64/include/asm/xor.h
+++ b/arch/arm64/include/asm/xor.h
@@ -9,7 +9,7 @@
 #include <linux/hardirq.h>
 #include <asm-generic/xor.h>
 #include <asm/hwcap.h>
-#include <asm/neon.h>
+#include <asm/simd.h>
 
 #ifdef CONFIG_KERNEL_MODE_NEON
 
@@ -19,9 +19,8 @@ static void
 xor_neon_2(unsigned long bytes, unsigned long * __restrict p1,
 	   const unsigned long * __restrict p2)
 {
-	kernel_neon_begin();
-	xor_block_inner_neon.do_2(bytes, p1, p2);
-	kernel_neon_end();
+	scoped_ksimd()
+		xor_block_inner_neon.do_2(bytes, p1, p2);
 }
 
 static void
@@ -29,9 +28,8 @@ xor_neon_3(unsigned long bytes, unsigned long * __restrict p1,
 	   const unsigned long * __restrict p2,
 	   const unsigned long * __restrict p3)
 {
-	kernel_neon_begin();
-	xor_block_inner_neon.do_3(bytes, p1, p2, p3);
-	kernel_neon_end();
+	scoped_ksimd()
+		xor_block_inner_neon.do_3(bytes, p1, p2, p3);
 }
 
 static void
@@ -40,9 +38,8 @@ xor_neon_4(unsigned long bytes, unsigned long * __restrict p1,
 	   const unsigned long * __restrict p3,
 	   const unsigned long * __restrict p4)
 {
-	kernel_neon_begin();
-	xor_block_inner_neon.do_4(bytes, p1, p2, p3, p4);
-	kernel_neon_end();
+	scoped_ksimd()
+		xor_block_inner_neon.do_4(bytes, p1, p2, p3, p4);
 }
 
 static void
@@ -52,9 +49,8 @@ xor_neon_5(unsigned long bytes, unsigned long * __restrict p1,
 	   const unsigned long * __restrict p4,
 	   const unsigned long * __restrict p5)
 {
-	kernel_neon_begin();
-	xor_block_inner_neon.do_5(bytes, p1, p2, p3, p4, p5);
-	kernel_neon_end();
+	scoped_ksimd()
+		xor_block_inner_neon.do_5(bytes, p1, p2, p3, p4, p5);
 }
 
 static struct xor_block_template xor_block_arm64 = {
-- 
2.51.0.710.ga91ca5db03-goog