linux-kernel - [PATCH v2] parisc: uaccess: fix compiler warnings caused by __put

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Date:	Mon, 22 Apr 2013 13:53:43 +0100
From:	Will Deacon <will.deacon@....com>
To:	linux-parisc@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Will Deacon <will.deacon@....com>,
	Helge Deller <deller@....de>
Subject: [PATCH v2] parisc: uaccess: fix compiler warnings caused by __put_user casting

When targetting 32-bit processors, __put_user emits a pair of stw
instructions for the 8-byte case. If the type of __val is a pointer, the
marshalling code casts it to the wider integer type of u64, resulting
in the following compiler warnings:

  kernel/signal.c: In function 'copy_siginfo_to_user':
  kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
  kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
  [...]

This patch fixes the warnings by removing the marshalling code and using
the correct output modifiers in the __put_{user,kernel}_asm64 macros
so that GCC will allocate the right registers without the need to
extract the two words explicitly.

Cc: Helge Deller <deller@....de>
Signed-off-by: Will Deacon <will.deacon@....com>
---

v1->v2: Put the output modifier on the correct word, so 64-bit put_user
        doesn't end up word-swapped.

 arch/parisc/include/asm/uaccess.h | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 4ba2c93..e0a8235 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -181,30 +181,24 @@ struct exception_data {
 #if !defined(CONFIG_64BIT)
 
 #define __put_kernel_asm64(__val,ptr) do {		    \
-	u64 __val64 = (u64)(__val);			    \
-	u32 hi = (__val64) >> 32;			    \
-	u32 lo = (__val64) & 0xffffffff;		    \
 	__asm__ __volatile__ (				    \
 		"\n1:\tstw %2,0(%1)"			    \
-		"\n2:\tstw %3,4(%1)\n\t"		    \
+		"\n2:\tstw %R2,4(%1)\n\t"		    \
 		ASM_EXCEPTIONTABLE_ENTRY(1b,fixup_put_user_skip_2)\
 		ASM_EXCEPTIONTABLE_ENTRY(2b,fixup_put_user_skip_1)\
 		: "=r"(__pu_err)                            \
-		: "r"(ptr), "r"(hi), "r"(lo), "0"(__pu_err) \
+		: "r"(ptr), "r"(__val), "0"(__pu_err) \
 		: "r1");				    \
 } while (0)
 
 #define __put_user_asm64(__val,ptr) do {	    	    \
-	u64 __val64 = (u64)(__val);			    \
-	u32 hi = (__val64) >> 32;			    \
-	u32 lo = (__val64) & 0xffffffff;		    \
 	__asm__ __volatile__ (				    \
 		"\n1:\tstw %2,0(%%sr3,%1)"		    \
-		"\n2:\tstw %3,4(%%sr3,%1)\n\t"		    \
+		"\n2:\tstw %R2,4(%%sr3,%1)\n\t"		    \
 		ASM_EXCEPTIONTABLE_ENTRY(1b,fixup_put_user_skip_2)\
 		ASM_EXCEPTIONTABLE_ENTRY(2b,fixup_put_user_skip_1)\
 		: "=r"(__pu_err)                            \
-		: "r"(ptr), "r"(hi), "r"(lo), "0"(__pu_err) \
+		: "r"(ptr), "r"(__val), "0"(__pu_err) \
 		: "r1");				    \
 } while (0)
 
-- 
1.8.0

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