linux-kernel - [PATCH] asm-generic: allow unaligned buffers in reads/writes{w,l,q}

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Message-Id: <20250203130323.8172-1-julian@outer-limits.org>
Date: Mon,  3 Feb 2025 14:03:23 +0100
From: Julian Vetter <julian@...er-limits.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Julian Vetter <julian@...er-limits.org>
Subject: [PATCH] asm-generic: allow unaligned buffers in reads/writes{w,l,q}

Access buffers in reads/writes{w,l,q} via get_unaligned and
put_unaligned, to protect from potential unaligned traps.

Signed-off-by: Julian Vetter <julian@...er-limits.org>
---
 include/asm-generic/io.h | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index a5cbbf3e26ec..920fecd512fc 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -12,6 +12,7 @@
 #include <linux/sizes.h>
 #include <linux/types.h>
 #include <linux/instruction_pointer.h>
+#include <linux/unaligned.h>
 
 #ifdef CONFIG_GENERIC_IOMAP
 #include <asm-generic/iomap.h>
@@ -422,7 +423,8 @@ static inline void readsw(const volatile void __iomem *addr, void *buffer,
 
 		do {
 			u16 x = __raw_readw(addr);
-			*buf++ = x;
+			put_unaligned(x, buf);
+			buf++;
 		} while (--count);
 	}
 }
@@ -438,7 +440,8 @@ static inline void readsl(const volatile void __iomem *addr, void *buffer,
 
 		do {
 			u32 x = __raw_readl(addr);
-			*buf++ = x;
+			put_unaligned(x, buf);
+			buf++;
 		} while (--count);
 	}
 }
@@ -455,7 +458,8 @@ static inline void readsq(const volatile void __iomem *addr, void *buffer,
 
 		do {
 			u64 x = __raw_readq(addr);
-			*buf++ = x;
+			put_unaligned(x, buf);
+			buf++;
 		} while (--count);
 	}
 }
@@ -486,7 +490,9 @@ static inline void writesw(volatile void __iomem *addr, const void *buffer,
 		const u16 *buf = buffer;
 
 		do {
-			__raw_writew(*buf++, addr);
+			u16 val = get_unaligned(buf);
+			__raw_writew(val, addr);
+			buf++;
 		} while (--count);
 	}
 }
@@ -501,7 +507,9 @@ static inline void writesl(volatile void __iomem *addr, const void *buffer,
 		const u32 *buf = buffer;
 
 		do {
-			__raw_writel(*buf++, addr);
+			u32 val = get_unaligned(buf);
+			__raw_writel(val, addr);
+			buf++;
 		} while (--count);
 	}
 }
@@ -517,7 +525,9 @@ static inline void writesq(volatile void __iomem *addr, const void *buffer,
 		const u64 *buf = buffer;
 
 		do {
-			__raw_writeq(*buf++, addr);
+			u64 val = get_unaligned(buf);
+			__raw_writeq(val, addr);
+			buf++;
 		} while (--count);
 	}
 }
-- 
2.34.1