1 #ifndef __LINUX_UACCESS_H__
2 #define __LINUX_UACCESS_H__
4 #include <linux/sched.h>
5 #include <asm/uaccess.h>
7 static __always_inline void pagefault_disabled_inc(void)
9 current->pagefault_disabled++;
12 static __always_inline void pagefault_disabled_dec(void)
14 current->pagefault_disabled--;
15 WARN_ON(current->pagefault_disabled < 0);
19 * These routines enable/disable the pagefault handler. If disabled, it will
20 * not take any locks and go straight to the fixup table.
22 * User access methods will not sleep when called from a pagefault_disabled()
25 static inline void pagefault_disable(void)
28 pagefault_disabled_inc();
30 * make sure to have issued the store before a pagefault
36 static inline void pagefault_enable(void)
39 * make sure to issue those last loads/stores before enabling
40 * the pagefault handler again.
43 pagefault_disabled_dec();
48 * Is the pagefault handler disabled? If so, user access methods will not sleep.
50 #define pagefault_disabled() (current->pagefault_disabled != 0)
53 * The pagefault handler is in general disabled by pagefault_disable() or
54 * when in irq context (via in_atomic()).
56 * This function should only be used by the fault handlers. Other users should
57 * stick to pagefault_disabled().
58 * Please NEVER use preempt_disable() to disable the fault handler. With
59 * !CONFIG_PREEMPT_COUNT, this is like a NOP. So the handler won't be disabled.
60 * in_atomic() will report different values based on !CONFIG_PREEMPT_COUNT.
62 #define faulthandler_disabled() (pagefault_disabled() || in_atomic())
64 #ifndef ARCH_HAS_NOCACHE_UACCESS
66 static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
67 const void __user *from, unsigned long n)
69 return __copy_from_user_inatomic(to, from, n);
72 static inline unsigned long __copy_from_user_nocache(void *to,
73 const void __user *from, unsigned long n)
75 return __copy_from_user(to, from, n);
78 #endif /* ARCH_HAS_NOCACHE_UACCESS */
81 * probe_kernel_address(): safely attempt to read from a location
82 * @addr: address to read from - its type is type typeof(retval)*
83 * @retval: read into this variable
85 * Safely read from address @addr into variable @revtal. If a kernel fault
86 * happens, handle that and return -EFAULT.
87 * We ensure that the __get_user() is executed in atomic context so that
88 * do_page_fault() doesn't attempt to take mmap_sem. This makes
89 * probe_kernel_address() suitable for use within regions where the caller
90 * already holds mmap_sem, or other locks which nest inside mmap_sem.
91 * This must be a macro because __get_user() needs to know the types of the
94 * We don't include enough header files to be able to do the set_fs(). We
95 * require that the probe_kernel_address() caller will do that.
97 #define probe_kernel_address(addr, retval) \
100 mm_segment_t old_fs = get_fs(); \
103 pagefault_disable(); \
104 ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \
105 pagefault_enable(); \
111 * probe_kernel_read(): safely attempt to read from a location
112 * @dst: pointer to the buffer that shall take the data
113 * @src: address to read from
114 * @size: size of the data chunk
116 * Safely read from address @src to the buffer at @dst. If a kernel fault
117 * happens, handle that and return -EFAULT.
119 extern long probe_kernel_read(void *dst, const void *src, size_t size);
120 extern long __probe_kernel_read(void *dst, const void *src, size_t size);
123 * probe_kernel_write(): safely attempt to write to a location
124 * @dst: address to write to
125 * @src: pointer to the data that shall be written
126 * @size: size of the data chunk
128 * Safely write to address @dst from the buffer at @src. If a kernel fault
129 * happens, handle that and return -EFAULT.
131 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
132 extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
134 #endif /* __LINUX_UACCESS_H__ */