m68k/uaccess: Revive 64-bit get_user()

Revive support for 64-bit get_user(), which was disabled in commit
d94af931af42152e ("[PATCH] m68k: clean up uaccess.h") due to a "broken"
typeof in (then brand new) gcc-4.1.

  - Keep on using u64 for the temporary, as __typeof__() doesn't drop
    the const qualifier,
  - Move it into a union (like mips32 does) to get rid of the cast, as
    using get_user() to fetch a __user pointer would cause a "cast to
    pointer from integer of different size" warning otherwise.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Martijn Coenen <maco@android.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/arch/m68k/include/asm/uaccess_mm.h b/arch/m68k/include/asm/uaccess_mm.h
index 75c172e909ac..c4cb889660aa 100644
--- a/arch/m68k/include/asm/uaccess_mm.h
+++ b/arch/m68k/include/asm/uaccess_mm.h
@@ -141,10 +141,12 @@ asm volatile ("\n"					\
         case 4:                                                         \
                 __get_user_asm(__gu_err, x, ptr, u32, l, r, -EFAULT);   \
                 break;                                                  \
-/*      case 8: disabled because gcc-4.1 has a broken typeof            \
-            {                                                           \
-                const void *__gu_ptr = (ptr);                           \
-                u64 __gu_val;                                           \
+        case 8: {                                                       \
+                const void *__gu_ptr = (ptr);                           \
+                union {                                                 \
+                        u64 l;                                          \
+                        __typeof__(*(ptr)) t;                           \
+                } __gu_val;                                             \
                 asm volatile ("\n"                                      \
                         "1:     "MOVES".l       (%2)+,%1\n"             \
                         "2:     "MOVES".l       (%2),%R1\n"             \
@@ -162,13 +164,13 @@ asm volatile ("\n"					\
                         "       .long   1b,10b\n"                       \
                         "       .long   2b,10b\n"                       \
                         "       .previous"                              \
-                        : "+d" (__gu_err), "=&r" (__gu_val),            \
+                        : "+d" (__gu_err), "=&r" (__gu_val.l),          \
                           "+a" (__gu_ptr)                               \
                         : "i" (-EFAULT)                                 \
                         : "memory");                                    \
-                (x) = (__force typeof(*(ptr)))__gu_val;                 \
+                (x) = __gu_val.t;                                       \
                 break;                                                  \
-            }   */                                                      \
+        }                                                               \
         default:                                                        \
                 __gu_err = __get_user_bad();                            \
                 break;                                                  \