1#ifndef __LINUX_UACCESS_H__
  2#define __LINUX_UACCESS_H__
  3
  4#include <linux/sched.h>
  5#include <asm/uaccess.h>
  6
  7static __always_inline void pagefault_disabled_inc(void)
  8{
  9	current->pagefault_disabled++;
 10}
 11
 12static __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 */
 25static 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
 35static 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
 64static 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
 70static 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 */
 87extern long probe_kernel_read(void *dst, const void *src, size_t size);
 88extern 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 */
 99extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
100extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
101
102extern 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, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0)
118#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
119#endif
120
121#endif		/* __LINUX_UACCESS_H__ */

  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 */
 16static inline void pagefault_disable(void)
 17{
 18	preempt_count_inc();
 19	/*
 20	 * make sure to have issued the store before a pagefault
 21	 * can hit.
 22	 */
 23	barrier();
 24}
 25
 26static inline void pagefault_enable(void)
 27{
 28#ifndef CONFIG_PREEMPT
 29	/*
 30	 * make sure to issue those last loads/stores before enabling
 31	 * the pagefault handler again.
 32	 */
 33	barrier();
 34	preempt_count_dec();
 35#else
 36	preempt_enable();
 37#endif
 38}
 39
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 40#ifndef ARCH_HAS_NOCACHE_UACCESS
 41
 42static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
 43				const void __user *from, unsigned long n)
 44{
 45	return __copy_from_user_inatomic(to, from, n);
 46}
 47
 48static inline unsigned long __copy_from_user_nocache(void *to,
 49				const void __user *from, unsigned long n)
 50{
 51	return __copy_from_user(to, from, n);
 52}
 53
 54#endif		/* ARCH_HAS_NOCACHE_UACCESS */
 55
 56/**
 57 * probe_kernel_address(): safely attempt to read from a location
 58 * @addr: address to read from - its type is type typeof(retval)*
 59 * @retval: read into this variable
 60 *
 61 * Safely read from address @addr into variable @revtal.  If a kernel fault
 62 * happens, handle that and return -EFAULT.
 63 * We ensure that the __get_user() is executed in atomic context so that
 64 * do_page_fault() doesn't attempt to take mmap_sem.  This makes
 65 * probe_kernel_address() suitable for use within regions where the caller
 66 * already holds mmap_sem, or other locks which nest inside mmap_sem.
 67 * This must be a macro because __get_user() needs to know the types of the
 68 * args.
 69 *
 70 * We don't include enough header files to be able to do the set_fs().  We
 71 * require that the probe_kernel_address() caller will do that.
 72 */
 73#define probe_kernel_address(addr, retval)		\
 74	({						\
 75		long ret;				\
 76		mm_segment_t old_fs = get_fs();		\
 77							\
 78		set_fs(KERNEL_DS);			\
 79		pagefault_disable();			\
 80		ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval));		\
 81		pagefault_enable();			\
 82		set_fs(old_fs);				\
 83		ret;					\
 84	})
 85
 86/*
 87 * probe_kernel_read(): safely attempt to read from a location
 88 * @dst: pointer to the buffer that shall take the data
 89 * @src: address to read from
 90 * @size: size of the data chunk
 91 *
 92 * Safely read from address @src to the buffer at @dst.  If a kernel fault
 93 * happens, handle that and return -EFAULT.
 94 */
 95extern long probe_kernel_read(void *dst, const void *src, size_t size);
 96extern long __probe_kernel_read(void *dst, const void *src, size_t size);
 97
 98/*
 99 * probe_kernel_write(): safely attempt to write to a location
100 * @dst: address to write to
101 * @src: pointer to the data that shall be written
102 * @size: size of the data chunk
103 *
104 * Safely write to address @dst from the buffer at @src.  If a kernel fault
105 * happens, handle that and return -EFAULT.
106 */
107extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
108extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
109
110#endif		/* __LINUX_UACCESS_H__ */