[XEN PATCH v2 2/3] x86/uaccess: replace __{get,put}_user_bad() with STATIC_ASSERT_UNREACHABLE()

[Federico Serafini <federico.serafini@xxxxxxxxxxx>]

Use STATIC_ASSERT_UNREACHABLE() to improve readability and anticipate
the build failure (from a linker error to an assembler error) in case
of wrong size.

Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
---
 xen/arch/x86/include/asm/uaccess.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/include/asm/uaccess.h 
b/xen/arch/x86/include/asm/uaccess.h
index 7443519d5b..52faf1d919 100644
--- a/xen/arch/x86/include/asm/uaccess.h
+++ b/xen/arch/x86/include/asm/uaccess.h
@@ -21,9 +21,6 @@ unsigned int copy_from_guest_ll(void *to, const void __user 
*from, unsigned int
 unsigned int copy_to_unsafe_ll(void *to, const void *from, unsigned int n);
 unsigned int copy_from_unsafe_ll(void *to, const void *from, unsigned int n);
 
-extern long __get_user_bad(void);
-extern void __put_user_bad(void);
-
 #define UA_KEEP(args...) args
 #define UA_DROP(args...)
 
@@ -208,7 +205,7 @@ do {                                                        
               \
     case 8:                                                                \
         put_unsafe_asm(x, ptr, grd, retval, "q",  "", "ir", errret);       \
         break;                                                             \
-    default: __put_user_bad();                                             \
+    default: STATIC_ASSERT_UNREACHABLE();                                  \
     }                                                                      \
     clac();                                                                \
 } while ( false )
@@ -227,7 +224,7 @@ do {                                                        
               \
     case 2: get_unsafe_asm(x, ptr, grd, retval, "w", "=r", errret); break; \
     case 4: get_unsafe_asm(x, ptr, grd, retval, "k", "=r", errret); break; \
     case 8: get_unsafe_asm(x, ptr, grd, retval,  "", "=r", errret); break; \
-    default: __get_user_bad();                                             \
+    default: STATIC_ASSERT_UNREACHABLE();                                  \
     }                                                                      \
     clac();                                                                \
 } while ( false )
-- 
2.34.1