1 #ifndef __LINUX_UACCESS_H__ 2 #define __LINUX_UACCESS_H__ 3 4 #include <linux/preempt.h> 5 #include <asm/uaccess.h> 6 7 /* 8 * These routines enable/disable the pagefault handler in that 9 * it will not take any locks and go straight to the fixup table. 10 * 11 * They have great resemblance to the preempt_disable/enable calls 12 * and in fact they are identical; this is because currently there is 13 * no other way to make the pagefault handlers do this. So we do 14 * disable preemption but we don't necessarily care about that. 15 */ 16 static inline void pagefault_disable(void) 17 { 18 inc_preempt_count(); 19 /* 20 * make sure to have issued the store before a pagefault 21 * can hit. 22 */ 23 barrier(); 24 } 25 26 static inline void pagefault_enable(void) 27 { 28 /* 29 * make sure to issue those last loads/stores before enabling 30 * the pagefault handler again. 31 */ 32 barrier(); 33 dec_preempt_count(); 34 /* 35 * make sure we do.. 36 */ 37 barrier(); 38 preempt_check_resched(); 39 } 40 41 #ifndef ARCH_HAS_NOCACHE_UACCESS 42 43 static inline unsigned long __copy_from_user_inatomic_nocache(void *to, 44 const void __user *from, unsigned long n) 45 { 46 return __copy_from_user_inatomic(to, from, n); 47 } 48 49 static inline unsigned long __copy_from_user_nocache(void *to, 50 const void __user *from, unsigned long n) 51 { 52 return __copy_from_user(to, from, n); 53 } 54 55 #endif /* ARCH_HAS_NOCACHE_UACCESS */ 56 57 /** 58 * probe_kernel_address(): safely attempt to read from a location 59 * @addr: address to read from - its type is type typeof(retval)* 60 * @retval: read into this variable 61 * 62 * Safely read from address @addr into variable @revtal. If a kernel fault 63 * happens, handle that and return -EFAULT. 64 * We ensure that the __get_user() is executed in atomic context so that 65 * do_page_fault() doesn't attempt to take mmap_sem. This makes 66 * probe_kernel_address() suitable for use within regions where the caller 67 * already holds mmap_sem, or other locks which nest inside mmap_sem. 68 * This must be a macro because __get_user() needs to know the types of the 69 * args. 70 * 71 * We don't include enough header files to be able to do the set_fs(). We 72 * require that the probe_kernel_address() caller will do that. 73 */ 74 #define probe_kernel_address(addr, retval) \ 75 ({ \ 76 long ret; \ 77 mm_segment_t old_fs = get_fs(); \ 78 \ 79 set_fs(KERNEL_DS); \ 80 pagefault_disable(); \ 81 ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \ 82 pagefault_enable(); \ 83 set_fs(old_fs); \ 84 ret; \ 85 }) 86 87 /* 88 * probe_kernel_read(): safely attempt to read from a location 89 * @dst: pointer to the buffer that shall take the data 90 * @src: address to read from 91 * @size: size of the data chunk 92 * 93 * Safely read from address @src to the buffer at @dst. If a kernel fault 94 * happens, handle that and return -EFAULT. 95 */ 96 extern long probe_kernel_read(void *dst, const void *src, size_t size); 97 extern long __probe_kernel_read(void *dst, const void *src, size_t size); 98 99 /* 100 * probe_kernel_write(): safely attempt to write to a location 101 * @dst: address to write to 102 * @src: pointer to the data that shall be written 103 * @size: size of the data chunk 104 * 105 * Safely write to address @dst from the buffer at @src. If a kernel fault 106 * happens, handle that and return -EFAULT. 107 */ 108 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); 109 extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); 110 111 #endif /* __LINUX_UACCESS_H__ */ 112