| #ifndef __LINUX_UACCESS_H__ |
| #define __LINUX_UACCESS_H__ |
| |
| #include <linux/preempt.h> |
| #include <asm/uaccess.h> |
| |
| /* |
| * These routines enable/disable the pagefault handler in that |
| * it will not take any locks and go straight to the fixup table. |
| * |
| * They have great resemblance to the preempt_disable/enable calls |
| * and in fact they are identical; this is because currently there is |
| * no other way to make the pagefault handlers do this. So we do |
| * disable preemption but we don't necessarily care about that. |
| */ |
| static inline void pagefault_disable(void) |
| { |
| inc_preempt_count(); |
| /* |
| * make sure to have issued the store before a pagefault |
| * can hit. |
| */ |
| barrier(); |
| } |
| |
| static inline void pagefault_enable(void) |
| { |
| /* |
| * make sure to issue those last loads/stores before enabling |
| * the pagefault handler again. |
| */ |
| barrier(); |
| dec_preempt_count(); |
| /* |
| * make sure we do.. |
| */ |
| barrier(); |
| preempt_check_resched(); |
| } |
| |
| #ifndef ARCH_HAS_NOCACHE_UACCESS |
| |
| static inline unsigned long __copy_from_user_inatomic_nocache(void *to, |
| const void __user *from, unsigned long n) |
| { |
| return __copy_from_user_inatomic(to, from, n); |
| } |
| |
| static inline unsigned long __copy_from_user_nocache(void *to, |
| const void __user *from, unsigned long n) |
| { |
| return __copy_from_user(to, from, n); |
| } |
| |
| #endif /* ARCH_HAS_NOCACHE_UACCESS */ |
| |
| /** |
| * probe_kernel_address(): safely attempt to read from a location |
| * @addr: address to read from - its type is type typeof(retval)* |
| * @retval: read into this variable |
| * |
| * Safely read from address @addr into variable @revtal. If a kernel fault |
| * happens, handle that and return -EFAULT. |
| * We ensure that the __get_user() is executed in atomic context so that |
| * do_page_fault() doesn't attempt to take mmap_sem. This makes |
| * probe_kernel_address() suitable for use within regions where the caller |
| * already holds mmap_sem, or other locks which nest inside mmap_sem. |
| * This must be a macro because __get_user() needs to know the types of the |
| * args. |
| * |
| * We don't include enough header files to be able to do the set_fs(). We |
| * require that the probe_kernel_address() caller will do that. |
| */ |
| #define probe_kernel_address(addr, retval) \ |
| ({ \ |
| long ret; \ |
| mm_segment_t old_fs = get_fs(); \ |
| \ |
| set_fs(KERNEL_DS); \ |
| pagefault_disable(); \ |
| ret = __get_user(retval, addr); \ |
| pagefault_enable(); \ |
| set_fs(old_fs); \ |
| ret; \ |
| }) |
| |
| #endif /* __LINUX_UACCESS_H__ */ |