![David Hildenbrand](/assets/img/avatar_default.png)
In general, non-atomic variants of user access functions must not sleep if pagefaults are disabled. Let's update all relevant comments in uaccess code. This also reflects the might_sleep() checks in might_fault(). Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-4-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
329 lines
9.7 KiB
C
329 lines
9.7 KiB
C
/*
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* Copyright (C) 2004-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_UACCESS_H
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#define __ASM_AVR32_UACCESS_H
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#include <linux/errno.h>
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#include <linux/sched.h>
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#define VERIFY_READ 0
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#define VERIFY_WRITE 1
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typedef struct {
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unsigned int is_user_space;
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} mm_segment_t;
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/*
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* The fs value determines whether argument validity checking should be
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* performed or not. If get_fs() == USER_DS, checking is performed, with
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* get_fs() == KERNEL_DS, checking is bypassed.
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*
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* For historical reasons (Data Segment Register?), these macros are misnamed.
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*/
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#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
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#define segment_eq(a, b) ((a).is_user_space == (b).is_user_space)
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#define USER_ADDR_LIMIT 0x80000000
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#define KERNEL_DS MAKE_MM_SEG(0)
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#define USER_DS MAKE_MM_SEG(1)
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#define get_ds() (KERNEL_DS)
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static inline mm_segment_t get_fs(void)
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{
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return MAKE_MM_SEG(test_thread_flag(TIF_USERSPACE));
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}
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static inline void set_fs(mm_segment_t s)
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{
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if (s.is_user_space)
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set_thread_flag(TIF_USERSPACE);
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else
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clear_thread_flag(TIF_USERSPACE);
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}
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/*
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* Test whether a block of memory is a valid user space address.
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* Returns 0 if the range is valid, nonzero otherwise.
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*
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* We do the following checks:
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* 1. Is the access from kernel space?
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* 2. Does (addr + size) set the carry bit?
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* 3. Is (addr + size) a negative number (i.e. >= 0x80000000)?
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*
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* If yes on the first check, access is granted.
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* If no on any of the others, access is denied.
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*/
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#define __range_ok(addr, size) \
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(test_thread_flag(TIF_USERSPACE) \
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&& (((unsigned long)(addr) >= 0x80000000) \
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|| ((unsigned long)(size) > 0x80000000) \
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|| (((unsigned long)(addr) + (unsigned long)(size)) > 0x80000000)))
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#define access_ok(type, addr, size) (likely(__range_ok(addr, size) == 0))
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/* Generic arbitrary sized copy. Return the number of bytes NOT copied */
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extern __kernel_size_t __copy_user(void *to, const void *from,
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__kernel_size_t n);
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extern __kernel_size_t copy_to_user(void __user *to, const void *from,
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__kernel_size_t n);
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extern __kernel_size_t copy_from_user(void *to, const void __user *from,
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__kernel_size_t n);
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static inline __kernel_size_t __copy_to_user(void __user *to, const void *from,
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__kernel_size_t n)
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{
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return __copy_user((void __force *)to, from, n);
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}
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static inline __kernel_size_t __copy_from_user(void *to,
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const void __user *from,
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__kernel_size_t n)
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{
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return __copy_user(to, (const void __force *)from, n);
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}
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#define __copy_to_user_inatomic __copy_to_user
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#define __copy_from_user_inatomic __copy_from_user
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/*
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* put_user: - Write a simple value into user space.
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* @x: Value to copy to user space.
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* @ptr: Destination address, in user space.
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* This macro copies a single simple value from kernel space to user
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and @x must be assignable
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* to the result of dereferencing @ptr.
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*
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* Returns zero on success, or -EFAULT on error.
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*/
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#define put_user(x, ptr) \
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__put_user_check((x), (ptr), sizeof(*(ptr)))
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/*
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* get_user: - Get a simple variable from user space.
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* @x: Variable to store result.
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* @ptr: Source address, in user space.
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* This macro copies a single simple variable from user space to kernel
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and the result of
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* dereferencing @ptr must be assignable to @x without a cast.
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*
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* Returns zero on success, or -EFAULT on error.
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* On error, the variable @x is set to zero.
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*/
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#define get_user(x, ptr) \
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__get_user_check((x), (ptr), sizeof(*(ptr)))
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/*
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* __put_user: - Write a simple value into user space, with less checking.
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* @x: Value to copy to user space.
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* @ptr: Destination address, in user space.
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* This macro copies a single simple value from kernel space to user
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and @x must be assignable
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* to the result of dereferencing @ptr.
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*
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* Caller must check the pointer with access_ok() before calling this
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* function.
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*
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* Returns zero on success, or -EFAULT on error.
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*/
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#define __put_user(x, ptr) \
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__put_user_nocheck((x), (ptr), sizeof(*(ptr)))
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/*
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* __get_user: - Get a simple variable from user space, with less checking.
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* @x: Variable to store result.
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* @ptr: Source address, in user space.
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*
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* Context: User context only. This function may sleep if pagefaults are
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* enabled.
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*
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* This macro copies a single simple variable from user space to kernel
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* space. It supports simple types like char and int, but not larger
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* data types like structures or arrays.
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*
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* @ptr must have pointer-to-simple-variable type, and the result of
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* dereferencing @ptr must be assignable to @x without a cast.
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*
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* Caller must check the pointer with access_ok() before calling this
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* function.
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*
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* Returns zero on success, or -EFAULT on error.
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* On error, the variable @x is set to zero.
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*/
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#define __get_user(x, ptr) \
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__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
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extern int __get_user_bad(void);
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extern int __put_user_bad(void);
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#define __get_user_nocheck(x, ptr, size) \
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({ \
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unsigned long __gu_val = 0; \
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int __gu_err = 0; \
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\
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switch (size) { \
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case 1: __get_user_asm("ub", __gu_val, ptr, __gu_err); break; \
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case 2: __get_user_asm("uh", __gu_val, ptr, __gu_err); break; \
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case 4: __get_user_asm("w", __gu_val, ptr, __gu_err); break; \
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default: __gu_err = __get_user_bad(); break; \
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} \
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\
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x = (__force typeof(*(ptr)))__gu_val; \
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__gu_err; \
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})
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#define __get_user_check(x, ptr, size) \
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({ \
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unsigned long __gu_val = 0; \
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const typeof(*(ptr)) __user * __gu_addr = (ptr); \
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int __gu_err = 0; \
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\
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if (access_ok(VERIFY_READ, __gu_addr, size)) { \
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switch (size) { \
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case 1: \
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__get_user_asm("ub", __gu_val, __gu_addr, \
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__gu_err); \
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break; \
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case 2: \
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__get_user_asm("uh", __gu_val, __gu_addr, \
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__gu_err); \
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break; \
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case 4: \
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__get_user_asm("w", __gu_val, __gu_addr, \
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__gu_err); \
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break; \
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default: \
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__gu_err = __get_user_bad(); \
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break; \
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} \
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} else { \
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__gu_err = -EFAULT; \
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} \
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x = (__force typeof(*(ptr)))__gu_val; \
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__gu_err; \
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})
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#define __get_user_asm(suffix, __gu_val, ptr, __gu_err) \
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asm volatile( \
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"1: ld." suffix " %1, %3 \n" \
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"2: \n" \
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" .subsection 1 \n" \
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"3: mov %0, %4 \n" \
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" rjmp 2b \n" \
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" .subsection 0 \n" \
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" .section __ex_table, \"a\" \n" \
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" .long 1b, 3b \n" \
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" .previous \n" \
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: "=r"(__gu_err), "=r"(__gu_val) \
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: "0"(__gu_err), "m"(*(ptr)), "i"(-EFAULT))
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#define __put_user_nocheck(x, ptr, size) \
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({ \
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typeof(*(ptr)) __pu_val; \
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int __pu_err = 0; \
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\
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__pu_val = (x); \
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switch (size) { \
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case 1: __put_user_asm("b", ptr, __pu_val, __pu_err); break; \
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case 2: __put_user_asm("h", ptr, __pu_val, __pu_err); break; \
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case 4: __put_user_asm("w", ptr, __pu_val, __pu_err); break; \
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case 8: __put_user_asm("d", ptr, __pu_val, __pu_err); break; \
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default: __pu_err = __put_user_bad(); break; \
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} \
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__pu_err; \
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})
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#define __put_user_check(x, ptr, size) \
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({ \
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typeof(*(ptr)) __pu_val; \
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typeof(*(ptr)) __user *__pu_addr = (ptr); \
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int __pu_err = 0; \
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\
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__pu_val = (x); \
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if (access_ok(VERIFY_WRITE, __pu_addr, size)) { \
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switch (size) { \
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case 1: \
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__put_user_asm("b", __pu_addr, __pu_val, \
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__pu_err); \
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break; \
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case 2: \
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__put_user_asm("h", __pu_addr, __pu_val, \
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__pu_err); \
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break; \
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case 4: \
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__put_user_asm("w", __pu_addr, __pu_val, \
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__pu_err); \
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break; \
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case 8: \
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__put_user_asm("d", __pu_addr, __pu_val, \
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__pu_err); \
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break; \
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default: \
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__pu_err = __put_user_bad(); \
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break; \
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} \
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} else { \
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__pu_err = -EFAULT; \
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} \
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__pu_err; \
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})
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#define __put_user_asm(suffix, ptr, __pu_val, __gu_err) \
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asm volatile( \
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"1: st." suffix " %1, %3 \n" \
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"2: \n" \
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" .subsection 1 \n" \
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"3: mov %0, %4 \n" \
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" rjmp 2b \n" \
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" .subsection 0 \n" \
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" .section __ex_table, \"a\" \n" \
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" .long 1b, 3b \n" \
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" .previous \n" \
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: "=r"(__gu_err), "=m"(*(ptr)) \
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: "0"(__gu_err), "r"(__pu_val), "i"(-EFAULT))
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extern __kernel_size_t clear_user(void __user *addr, __kernel_size_t size);
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extern __kernel_size_t __clear_user(void __user *addr, __kernel_size_t size);
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extern long strncpy_from_user(char *dst, const char __user *src, long count);
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extern long __strncpy_from_user(char *dst, const char __user *src, long count);
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extern long strnlen_user(const char __user *__s, long __n);
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extern long __strnlen_user(const char __user *__s, long __n);
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#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
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struct exception_table_entry
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{
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unsigned long insn, fixup;
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};
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#endif /* __ASM_AVR32_UACCESS_H */
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