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