linux-kernel - [PATCH 3.10 11/17] m68k/uaccess: Fix asm constraints for userspace access

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Message-Id: <20151023174453.822639440@linuxfoundation.org>
Date:	Fri, 23 Oct 2015 10:44:56 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Geert Uytterhoeven <geert@...ux-m68k.org>,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 3.10 11/17] m68k/uaccess: Fix asm constraints for userspace access

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert@...ux-m68k.org>

commit 631d8b674f5f8235e9cb7e628b0fe9e5200e3158 upstream.

When compiling a MMU kernel with CPU_HAS_ADDRESS_SPACES=n (e.g. "MMU=y
allnoconfig": "echo CONFIG_MMU=y > allno.config && make KCONFIG_ALLCONFIG=1
allnoconfig"), we use plain "move" instead of "moves", and I got:

  CC      arch/m68k/lib/uaccess.o
{standard input}: Assembler messages:
{standard input}:47: Error: operands mismatch -- statement `move.b %a0,(%a1)' ignored

This happens because plain "move" doesn't support byte transfers between
memory and address registers, while "moves" does.

Fix the asm constraints for __generic_copy_from_user(),
__generic_copy_to_user(), and __clear_user() to only use data registers
when accessing userspace.

Also, relax the asm constraints for 16-bit userspace accesses in
__put_user() and __get_user(), as both "move" and "moves" do support
such transfers between memory and address registers.

Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/m68k/include/asm/uaccess_mm.h |    8 ++++----
 arch/m68k/lib/uaccess.c            |    6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess_mm.h
@@ -90,7 +90,7 @@ asm volatile ("\n"					\
 		__put_user_asm(__pu_err, __pu_val, ptr, b, d, -EFAULT);	\
 		break;							\
 	case 2:								\
-		__put_user_asm(__pu_err, __pu_val, ptr, w, d, -EFAULT);	\
+		__put_user_asm(__pu_err, __pu_val, ptr, w, r, -EFAULT);	\
 		break;							\
 	case 4:								\
 		__put_user_asm(__pu_err, __pu_val, ptr, l, r, -EFAULT);	\
@@ -158,7 +158,7 @@ asm volatile ("\n"					\
 		__get_user_asm(__gu_err, x, ptr, u8, b, d, -EFAULT);	\
 		break;							\
 	case 2:								\
-		__get_user_asm(__gu_err, x, ptr, u16, w, d, -EFAULT);	\
+		__get_user_asm(__gu_err, x, ptr, u16, w, r, -EFAULT);	\
 		break;							\
 	case 4:								\
 		__get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);	\
@@ -245,7 +245,7 @@ __constant_copy_from_user(void *to, cons
 		__get_user_asm(res, *(u8 *)to, (u8 __user *)from, u8, b, d, 1);
 		break;
 	case 2:
-		__get_user_asm(res, *(u16 *)to, (u16 __user *)from, u16, w, d, 2);
+		__get_user_asm(res, *(u16 *)to, (u16 __user *)from, u16, w, r, 2);
 		break;
 	case 3:
 		__constant_copy_from_user_asm(res, to, from, tmp, 3, w, b,);
@@ -326,7 +326,7 @@ __constant_copy_to_user(void __user *to,
 		__put_user_asm(res, *(u8 *)from, (u8 __user *)to, b, d, 1);
 		break;
 	case 2:
-		__put_user_asm(res, *(u16 *)from, (u16 __user *)to, w, d, 2);
+		__put_user_asm(res, *(u16 *)from, (u16 __user *)to, w, r, 2);
 		break;
 	case 3:
 		__constant_copy_to_user_asm(res, to, from, tmp, 3, w, b,);
--- a/arch/m68k/lib/uaccess.c
+++ b/arch/m68k/lib/uaccess.c
@@ -52,7 +52,7 @@ unsigned long __generic_copy_from_user(v
 		"	.long	3b,30b\n"
 		"	.long	5b,50b\n"
 		"	.previous"
-		: "=d" (res), "+a" (from), "+a" (to), "=&r" (tmp)
+		: "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
 		: "0" (n / 4), "d" (n & 3));
 
 	return res;
@@ -96,7 +96,7 @@ unsigned long __generic_copy_to_user(voi
 		"	.long	7b,50b\n"
 		"	.long	8b,50b\n"
 		"	.previous"
-		: "=d" (res), "+a" (from), "+a" (to), "=&r" (tmp)
+		: "=d" (res), "+a" (from), "+a" (to), "=&d" (tmp)
 		: "0" (n / 4), "d" (n & 3));
 
 	return res;
@@ -141,7 +141,7 @@ unsigned long __clear_user(void __user *
 		"	.long	7b,40b\n"
 		"	.previous"
 		: "=d" (res), "+a" (to)
-		: "r" (0), "0" (n / 4), "d" (n & 3));
+		: "d" (0), "0" (n / 4), "d" (n & 3));
 
     return res;
 }


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