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TOMOYO Linux Cross Reference
Linux/include/linux/uaccess.h

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  1 #ifndef __LINUX_UACCESS_H__
  2 #define __LINUX_UACCESS_H__
  3 
  4 #include <linux/sched.h>
  5 #include <asm/uaccess.h>
  6 
  7 static __always_inline void pagefault_disabled_inc(void)
  8 {
  9         current->pagefault_disabled++;
 10 }
 11 
 12 static __always_inline void pagefault_disabled_dec(void)
 13 {
 14         current->pagefault_disabled--;
 15         WARN_ON(current->pagefault_disabled < 0);
 16 }
 17 
 18 /*
 19  * These routines enable/disable the pagefault handler. If disabled, it will
 20  * not take any locks and go straight to the fixup table.
 21  *
 22  * User access methods will not sleep when called from a pagefault_disabled()
 23  * environment.
 24  */
 25 static inline void pagefault_disable(void)
 26 {
 27         pagefault_disabled_inc();
 28         /*
 29          * make sure to have issued the store before a pagefault
 30          * can hit.
 31          */
 32         barrier();
 33 }
 34 
 35 static inline void pagefault_enable(void)
 36 {
 37         /*
 38          * make sure to issue those last loads/stores before enabling
 39          * the pagefault handler again.
 40          */
 41         barrier();
 42         pagefault_disabled_dec();
 43 }
 44 
 45 /*
 46  * Is the pagefault handler disabled? If so, user access methods will not sleep.
 47  */
 48 #define pagefault_disabled() (current->pagefault_disabled != 0)
 49 
 50 /*
 51  * The pagefault handler is in general disabled by pagefault_disable() or
 52  * when in irq context (via in_atomic()).
 53  *
 54  * This function should only be used by the fault handlers. Other users should
 55  * stick to pagefault_disabled().
 56  * Please NEVER use preempt_disable() to disable the fault handler. With
 57  * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
 58  * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
 59  */
 60 #define faulthandler_disabled() (pagefault_disabled() || in_atomic())
 61 
 62 #ifndef ARCH_HAS_NOCACHE_UACCESS
 63 
 64 static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
 65                                 const void __user *from, unsigned long n)
 66 {
 67         return __copy_from_user_inatomic(to, from, n);
 68 }
 69 
 70 static inline unsigned long __copy_from_user_nocache(void *to,
 71                                 const void __user *from, unsigned long n)
 72 {
 73         return __copy_from_user(to, from, n);
 74 }
 75 
 76 #endif          /* ARCH_HAS_NOCACHE_UACCESS */
 77 
 78 /*
 79  * probe_kernel_read(): safely attempt to read from a location
 80  * @dst: pointer to the buffer that shall take the data
 81  * @src: address to read from
 82  * @size: size of the data chunk
 83  *
 84  * Safely read from address @src to the buffer at @dst.  If a kernel fault
 85  * happens, handle that and return -EFAULT.
 86  */
 87 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 88 extern long __probe_kernel_read(void *dst, const void *src, size_t size);
 89 
 90 /*
 91  * probe_kernel_write(): safely attempt to write to a location
 92  * @dst: address to write to
 93  * @src: pointer to the data that shall be written
 94  * @size: size of the data chunk
 95  *
 96  * Safely write to address @dst from the buffer at @src.  If a kernel fault
 97  * happens, handle that and return -EFAULT.
 98  */
 99 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
100 extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
101 
102 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
103 
104 /**
105  * probe_kernel_address(): safely attempt to read from a location
106  * @addr: address to read from
107  * @retval: read into this variable
108  *
109  * Returns 0 on success, or -EFAULT.
110  */
111 #define probe_kernel_address(addr, retval)              \
112         probe_kernel_read(&retval, addr, sizeof(retval))
113 
114 #ifndef user_access_begin
115 #define user_access_begin() do { } while (0)
116 #define user_access_end() do { } while (0)
117 #define unsafe_get_user(x, ptr) __get_user(x, ptr)
118 #define unsafe_put_user(x, ptr) __put_user(x, ptr)
119 #endif
120 
121 #endif          /* __LINUX_UACCESS_H__ */
122 

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