#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, (__force typeof(retval) __user *)(addr)); \ pagefault_enable(); \ set_fs(old_fs); \ ret; \ }) #endif /* __LINUX_UACCESS_H__ */