[U-Boot] [PATCH] Make the generic unaligned access code safe for unaligned access

[Stefan Roese]

Hi Remy,

On Wednesday 28 October 2009 22:13:38 Remy Bohmer wrote:
> The current generic code for handling unaligned access assumes that
> the processor can properly handle unaligned accesses itself.
> This is at least not the case for ARM, which results in runtime
> errors.
> 
> Rewrite it such that it works for ARM as well.

I introduced this header some time ago for UBIFS support (for PowerPC).
As you may have noticed, it's a copy from the Linux version. And I
would like to keep it this way if possible. Looking at the Linux ARM
version, the basic difference seems to be the header
"include/asm-arm/unaligned.h" which includes this file. The Linux
version of "unaligned.h" does *not* include "access_ok.h" at all. It
includes "le_byteshift.h" and "be_byteshift.h" instead. And I would
really like to keep this in sync with Linux if possible.

So why not do it this way (totally untested):

From 3e9aa23a66041f05b94f94b1326941331248a487 Mon Sep 17 00:00:00 2001
From: Stefan Roese <sr at denx.de>
Date: Thu, 29 Oct 2009 05:57:53 +0100
Subject: [PATCH] arm: Use Linux version for unaligned access code

Signed-off-by: Stefan Roese <sr at denx.de>
---
 include/asm-arm/unaligned.h            |    3 +-
 include/linux/unaligned/be_byteshift.h |   70 ++++++++++++++++++++++++++++++++
 include/linux/unaligned/le_byteshift.h |   70 ++++++++++++++++++++++++++++++++
 3 files changed, 142 insertions(+), 1 deletions(-)
 create mode 100644 include/linux/unaligned/be_byteshift.h
 create mode 100644 include/linux/unaligned/le_byteshift.h

diff --git a/include/asm-arm/unaligned.h b/include/asm-arm/unaligned.h
index d644df7..44593a8 100644
--- a/include/asm-arm/unaligned.h
+++ b/include/asm-arm/unaligned.h
@@ -1,7 +1,8 @@
 #ifndef _ASM_ARM_UNALIGNED_H
 #define _ASM_ARM_UNALIGNED_H
 
-#include <linux/unaligned/access_ok.h>
+#include <linux/unaligned/le_byteshift.h>
+#include <linux/unaligned/be_byteshift.h>
 #include <linux/unaligned/generic.h>
 
 /*
diff --git a/include/linux/unaligned/be_byteshift.h 
b/include/linux/unaligned/be_byteshift.h
new file mode 100644
index 0000000..9356b24
--- /dev/null
+++ b/include/linux/unaligned/be_byteshift.h
@@ -0,0 +1,70 @@
+#ifndef _LINUX_UNALIGNED_BE_BYTESHIFT_H
+#define _LINUX_UNALIGNED_BE_BYTESHIFT_H
+
+#include <linux/types.h>
+
+static inline u16 __get_unaligned_be16(const u8 *p)
+{
+	return p[0] << 8 | p[1];
+}
+
+static inline u32 __get_unaligned_be32(const u8 *p)
+{
+	return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
+}
+
+static inline u64 __get_unaligned_be64(const u8 *p)
+{
+	return (u64)__get_unaligned_be32(p) << 32 |
+	       __get_unaligned_be32(p + 4);
+}
+
+static inline void __put_unaligned_be16(u16 val, u8 *p)
+{
+	*p++ = val >> 8;
+	*p++ = val;
+}
+
+static inline void __put_unaligned_be32(u32 val, u8 *p)
+{
+	__put_unaligned_be16(val >> 16, p);
+	__put_unaligned_be16(val, p + 2);
+}
+
+static inline void __put_unaligned_be64(u64 val, u8 *p)
+{
+	__put_unaligned_be32(val >> 32, p);
+	__put_unaligned_be32(val, p + 4);
+}
+
+static inline u16 get_unaligned_be16(const void *p)
+{
+	return __get_unaligned_be16((const u8 *)p);
+}
+
+static inline u32 get_unaligned_be32(const void *p)
+{
+	return __get_unaligned_be32((const u8 *)p);
+}
+
+static inline u64 get_unaligned_be64(const void *p)
+{
+	return __get_unaligned_be64((const u8 *)p);
+}
+
+static inline void put_unaligned_be16(u16 val, void *p)
+{
+	__put_unaligned_be16(val, p);
+}
+
+static inline void put_unaligned_be32(u32 val, void *p)
+{
+	__put_unaligned_be32(val, p);
+}
+
+static inline void put_unaligned_be64(u64 val, void *p)
+{
+	__put_unaligned_be64(val, p);
+}
+
+#endif /* _LINUX_UNALIGNED_BE_BYTESHIFT_H */
diff --git a/include/linux/unaligned/le_byteshift.h 
b/include/linux/unaligned/le_byteshift.h
new file mode 100644
index 0000000..be376fb
--- /dev/null
+++ b/include/linux/unaligned/le_byteshift.h
@@ -0,0 +1,70 @@
+#ifndef _LINUX_UNALIGNED_LE_BYTESHIFT_H
+#define _LINUX_UNALIGNED_LE_BYTESHIFT_H
+
+#include <linux/types.h>
+
+static inline u16 __get_unaligned_le16(const u8 *p)
+{
+	return p[0] | p[1] << 8;
+}
+
+static inline u32 __get_unaligned_le32(const u8 *p)
+{
+	return p[0] | p[1] << 8 | p[2] << 16 | p[3] << 24;
+}
+
+static inline u64 __get_unaligned_le64(const u8 *p)
+{
+	return (u64)__get_unaligned_le32(p + 4) << 32 |
+	       __get_unaligned_le32(p);
+}
+
+static inline void __put_unaligned_le16(u16 val, u8 *p)
+{
+	*p++ = val;
+	*p++ = val >> 8;
+}
+
+static inline void __put_unaligned_le32(u32 val, u8 *p)
+{
+	__put_unaligned_le16(val >> 16, p + 2);
+	__put_unaligned_le16(val, p);
+}
+
+static inline void __put_unaligned_le64(u64 val, u8 *p)
+{
+	__put_unaligned_le32(val >> 32, p + 4);
+	__put_unaligned_le32(val, p);
+}
+
+static inline u16 get_unaligned_le16(const void *p)
+{
+	return __get_unaligned_le16((const u8 *)p);
+}
+
+static inline u32 get_unaligned_le32(const void *p)
+{
+	return __get_unaligned_le32((const u8 *)p);
+}
+
+static inline u64 get_unaligned_le64(const void *p)
+{
+	return __get_unaligned_le64((const u8 *)p);
+}
+
+static inline void put_unaligned_le16(u16 val, void *p)
+{
+	__put_unaligned_le16(val, p);
+}
+
+static inline void put_unaligned_le32(u32 val, void *p)
+{
+	__put_unaligned_le32(val, p);
+}
+
+static inline void put_unaligned_le64(u64 val, void *p)
+{
+	__put_unaligned_le64(val, p);
+}
+
+#endif /* _LINUX_UNALIGNED_LE_BYTESHIFT_H */
-- 
1.6.5.1

Please give it a try and feel free to submit this patch
with a better commit text if it works for you.

Cheers,
Stefan