Re: [PATCH v3] ARM: add get_user() support for 8 byte types

On Thursday 12 June 2014 16:42:35 Daniel Thompson wrote:

#define __get_user_check(x,p) \ ({ \ unsigned long __limit = current_thread_info()->addr_limit - 1; \ register const typeof(*(p)) __user *__p asm("r0") = (p);\

•           register unsigned long __r2 asm("r2");                  \
  

•           register typeof(x) __r2 asm("r2");                      \
            register unsigned long __l asm("r1") = __limit;         \
            register int __e asm("r0");                             \
            switch (sizeof(*(__p))) {                               \
  

@@ -142,6 +152,12 @@ extern int __get_user_4(void *); case 4: \ __get_user_x(__r2, __p, __e, __l, 4); \ break; \

•           case 8:                                                 \
  

•                   if (sizeof((x)) < 8)                            \
  

•                           __get_user_xb(__r2, __p, __e, __l, 4);  \
  

•                   else                                            \
  

•                           __get_user_x(__r2, __p, __e, __l, 8);   \
  

•                   break;                                          \
            default: __e = __get_user_bad(); break;                 \
            }                                                       \
            x = (typeof(*(p))) __r2;                                \
  
  

I don't think there is a way to do this without copying the __builtin_choose_expr() hack from x86.

Arnd