mn10300: fix kernel build failures when using gcc-4.x

Fix some build failures when using gcc-4.x for MN10300.

Firstly, __get_user() fails to build because the pointer points to a const and
__gu_val ends up being read-only:

In file included from include/linux/mempolicy.h:62,
                 from init/main.c:50:
include/linux/pagemap.h: In function 'fault_in_pages_readable':
include/linux/pagemap.h:394: error: read-only variable '__gu_val' used as 'asm' output
include/linux/pagemap.h:394: error: read-only variable '__gu_val' used as 'asm' output
include/linux/pagemap.h:394: error: read-only variable '__gu_val' used as 'asm' output
include/linux/pagemap.h:400: error: read-only variable '__gu_val' used as 'asm' output
include/linux/pagemap.h:400: error: read-only variable '__gu_val' used as 'asm' output
include/linux/pagemap.h:400: error: read-only variable '__gu_val' used as 'asm' output
make[1]: *** [init/main.o] Error 1

Secondly, gcc-4 doesn't allow casts of lvalues:

  UPD     include/linux/compile.h
arch/mn10300/kernel/rtc.c: In function 'calibrate_clock':
arch/mn10300/kernel/rtc.c:170: error: lvalue required as left operand of assignment
arch/mn10300/kernel/rtc.c:172: error: lvalue required as left operand of assignment
make[1]: *** [arch/mn10300/kernel/rtc.o] Error 1

These are seen with gcc 4.2.1.

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 39 insertions, 34 deletions

diff --git a/arch/mn10300/include/asm/uaccess.h b/arch/mn10300/include/asm/uaccess.h
index 8a3a4dd55763..167e10ff06d9 100644
--- a/arch/mn10300/include/asm/uaccess.h
+++ b/arch/mn10300/include/asm/uaccess.h
@@ -129,42 +129,47 @@ extern int fixup_exception(struct pt_regs *regs);
 struct __large_struct { unsigned long buf[100]; };
 #define __m(x) (*(struct __large_struct *)(x))
 
-#define __get_user_nocheck(x, ptr, size)        \
-({                                              \
-        __typeof(*(ptr)) __gu_val;              \
-        unsigned long __gu_addr;                \
-        int __gu_err;                           \
-        __gu_addr = (unsigned long) (ptr);      \
-        switch (size) {                         \
-        case 1:  __get_user_asm("bu"); break;   \
-        case 2:  __get_user_asm("hu"); break;   \
-        case 4:  __get_user_asm(""  ); break;   \
-        default: __get_user_unknown(); break;   \
-        }                                       \
-        x = (__typeof__(*(ptr))) __gu_val;      \
-        __gu_err;                               \
+#define __get_user_nocheck(x, ptr, size)                                \
+({                                                                      \
+        unsigned long __gu_addr;                                        \
+        int __gu_err;                                                   \
+        __gu_addr = (unsigned long) (ptr);                              \
+        switch (size) {                                                 \
+        case 1: {                                                       \
+                unsigned char __gu_val;                                 \
+                __get_user_asm("bu");                                   \
+                (x) = *(__force __typeof__(*(ptr))*) &__gu_val;         \
+                break;                                                  \
+        }                                                               \
+        case 2: {                                                       \
+                unsigned short __gu_val;                                \
+                __get_user_asm("hu");                                   \
+                (x) = *(__force __typeof__(*(ptr))*) &__gu_val;         \
+                break;                                                  \
+        }                                                               \
+        case 4: {                                                       \
+                unsigned int __gu_val;                                  \
+                __get_user_asm("");                                     \
+                (x) = *(__force __typeof__(*(ptr))*) &__gu_val;         \
+                break;                                                  \
+        }                                                               \
+        default:                                                        \
+                __get_user_unknown();                                   \
+                break;                                                  \
+        }                                                               \
+        __gu_err;                                                       \
 })
 
-#define __get_user_check(x, ptr, size)                  \
-({                                                      \
-        __typeof__(*(ptr)) __gu_val;                    \
-        unsigned long __gu_addr;                        \
-        int __gu_err;                                   \
-        __gu_addr = (unsigned long) (ptr);              \
-        if (likely(__access_ok(__gu_addr,size))) {      \
-                switch (size) {                         \
-                case 1:  __get_user_asm("bu"); break;   \
-                case 2:  __get_user_asm("hu"); break;   \
-                case 4:  __get_user_asm(""  ); break;   \
-                default: __get_user_unknown(); break;   \
-                }                                       \
-        }                                               \
-        else {                                          \
-                __gu_err = -EFAULT;                     \
-                __gu_val = 0;                           \
-        }                                               \
-        x = (__typeof__(*(ptr))) __gu_val;              \
-        __gu_err;                                       \
+#define __get_user_check(x, ptr, size)                                  \
+({                                                                      \
+        int _e;                                                         \
+        if (likely(__access_ok((unsigned long) (ptr), (size))))         \
+                _e = __get_user_nocheck((x), (ptr), (size));            \
+        else {                                                          \
+                _e = -EFAULT;                                           \
+                (x) = (__typeof__(x))0;                                 \
+        }                                                               \
+        _e;                                                             \
 })
 
 #define __get_user_asm(INSN)                                    \