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/*
* include/asm-xtensa/uaccess.h
*
* User space memory access functions
*
* These routines provide basic accessing functions to the user memory
* space for the kernel. This header file provides fuctions such as:
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*/
#ifndef _XTENSA_UACCESS_H
#define _XTENSA_UACCESS_H
#include <linux/errno.h>
#define VERIFY_READ 0
#define VERIFY_WRITE 1
#ifdef __ASSEMBLY__
#include <asm/current.h>
#include <asm/asm-offsets.h>
#include <asm/processor.h>
/*
* These assembly macros mirror the C macros that follow below. They
* should always have identical functionality. See
* arch/xtensa/kernel/sys.S for usage.
*/
#define KERNEL_DS 0
#define USER_DS 1
#define get_ds (KERNEL_DS)
/*
* get_fs reads current->thread.current_ds into a register.
* On Entry:
* <ad> anything
* <sp> stack
* On Exit:
* <ad> contains current->thread.current_ds
*/
.macro get_fs ad, sp
GET_CURRENT(\ad,\sp)
l32i \ad, \ad, THREAD_CURRENT_DS
.endm
/*
* set_fs sets current->thread.current_ds to some value.
* On Entry:
* <at> anything (temp register)
* <av> value to write
* <sp> stack
* On Exit:
* <at> destroyed (actually, current)
* <av> preserved, value to write
*/
.macro set_fs at, av, sp
GET_CURRENT(\at,\sp)
s32i \av, \at, THREAD_CURRENT_DS
.endm
/*
* kernel_ok determines whether we should bypass addr/size checking.
* See the equivalent C-macro version below for clarity.
* On success, kernel_ok branches to a label indicated by parameter
* <success>. This implies that the macro falls through to the next
* insruction on an error.
*
* Note that while this macro can be used independently, we designed
* in for optimal use in the access_ok macro below (i.e., we fall
* through on error).
*
* On Entry:
* <at> anything (temp register)
* <success> label to branch to on success; implies
* fall-through macro on error
* <sp> stack pointer
* On Exit:
* <at> destroyed (actually, current->thread.current_ds)
*/
#if ((KERNEL_DS != 0) || (USER_DS == 0))
# error Assembly macro kernel_ok fails
#endif
.macro kernel_ok at, sp, success
get_fs \at, \sp
beqz \at, \success
.endm
/*
* user_ok determines whether the access to user-space memory is allowed.
* See the equivalent C-macro version below for clarity.
*
* On error, user_ok branches to a label indicated by parameter
* <error>. This implies that the macro falls through to the next
* instruction on success.
*
* Note that while this macro can be used independently, we designed
* in for optimal use in the access_ok macro below (i.e., we fall
* through on success).
*
* On Entry:
* <aa> register containing memory address
* <as> register containing memory size
* <at> temp register
* <error> label to branch to on error; implies fall-through
* macro on success
* On Exit:
* <aa> preserved
* <as> preserved
* <at> destroyed (actually, (TASK_SIZE + 1 - size))
*/
.macro user_ok aa, as, at, error
movi \at, (TASK_SIZE+1)
bgeu \as, \at, \error
sub \at, \at, \as
bgeu \aa, \at, \error
.endm
/*
* access_ok determines whether a memory access is allowed. See the
* equivalent C-macro version below for clarity.
*
* On error, access_ok branches to a label indicated by parameter
* <error>. This implies that the macro falls through to the next
* instruction on success.
*
* Note that we assume success is the common case, and we optimize the
* branch fall-through case on success.
*
* On Entry:
* <aa> register containing memory address
* <as> register containing memory size
* <at> temp register
* <sp>
* <error> label to branch to on error; implies fall-through
* macro on success
* On Exit:
* <aa> preserved
* <as> preserved
* <at> destroyed
*/
.macro access_ok aa, as, at, sp, error
kernel_ok \at, \sp, .Laccess_ok_\@
user_ok \aa, \as, \at, \error
.Laccess_ok_\@:
.endm
#else /* __ASSEMBLY__ not defined */
#include <linux/sched.h>
#include <asm/types.h>
/*
* The fs value determines whether argument validity checking should
* be performed or not. If get_fs() == USER_DS, checking is
* performed, with get_fs() == KERNEL_DS, checking is bypassed.
*
* For historical reasons (Data Segment Register?), these macros are
* grossly misnamed.
*/
#define KERNEL_DS ((mm_segment_t) { 0 })
#define USER_DS ((mm_segment_t) { 1 })
#define get_ds() (KERNEL_DS)
#define get_fs() (current->thread.current_ds)
#define set_fs(val) (current->thread.current_ds = (val))
#define segment_eq(a,b) ((a).seg == (b).seg)
#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS))
#define __user_ok(addr,size) (((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
#define __access_ok(addr,size) (__kernel_ok || __user_ok((addr),(size)))
#define access_ok(type,addr,size) __access_ok((unsigned long)(addr),(size))
/*
* These are the main single-value transfer routines. They
* automatically use the right size if we just have the right pointer
* type.
*
* This gets kind of ugly. We want to return _two_ values in
* "get_user()" and yet we don't want to do any pointers, because that
* is too much of a performance impact. Thus we have a few rather ugly
* macros here, and hide all the uglyness from the user.
*
* Careful to not
* (a) re-use the arguments for side effects (sizeof is ok)
* (b) require any knowledge of processes at this stage
*/
#define put_user(x,ptr) __put_user_check((x),(ptr),sizeof(*(ptr)))
#define get_user(x,ptr) __get_user_check((x),(ptr),sizeof(*(ptr)))
/*
* The "__xxx" versions of the user access functions are versions that
* do not verify the address space, that must have been done previously
* with a separate "access_ok()" call (this is used when we do multiple
* accesses to the same area of user memory).
*/
#define __put_user(x,ptr) __put_user_nocheck((x),(ptr),sizeof(*(ptr)))
#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
extern long __put_user_bad(void);
#define __put_user_nocheck(x,ptr,size) \
({ \
long __pu_err; \
__put_user_size((x),(ptr),(size),__pu_err); \
__pu_err; \
})
#define __put_user_check(x,ptr,size) \
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) *__pu_addr = (ptr); \
if (access_ok(VERIFY_WRITE,__pu_addr,size)) \
__put_user_size((x),__pu_addr,(size),__pu_err); \
__pu_err; \
})
#define __put_user_size(x,ptr,size,retval) \
do { \
retval = 0; \
switch (size) { \
case 1: __put_user_asm(x,ptr,retval,1,"s8i"); break; \
case 2: __put_user_asm(x,ptr,retval,2,"s16i"); break; \
case 4: __put_user_asm(x,ptr,retval,4,"s32i"); break; \
case 8: { \
__typeof__(*ptr) __v64 = x; \
retval = __copy_to_user(ptr,&__v64,8); \
break; \
} \
default: __put_user_bad(); \
} \
} while (0)
/*
* Consider a case of a user single load/store would cause both an
* unaligned exception and an MMU-related exception (unaligned
* exceptions happen first):
*
* User code passes a bad variable ptr to a system call.
* Kernel tries to access the variable.
* Unaligned exception occurs.
* Unaligned exception handler tries to make aligned accesses.
* Double exception occurs for MMU-related cause (e.g., page not mapped).
* do_page_fault() thinks the fault address belongs to the kernel, not the
* user, and panics.
*
* The kernel currently prohibits user unaligned accesses. We use the
* __check_align_* macros to check for unaligned addresses before
* accessing user space so we don't crash the kernel. Both
* __put_user_asm and __get_user_asm use these alignment macros, so
* macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in
* sync.
*/
#define __check_align_1 ""
#define __check_align_2 \
" _bbci.l %2, 0, 1f \n" \
" movi %0, %3 \n" \
" _j 2f \n"
#define __check_align_4 \
" _bbsi.l %2, 0, 0f \n" \
" _bbci.l %2, 1, 1f \n" \
"0: movi %0, %3 \n" \
" _j 2f \n"
/*
* We don't tell gcc that we are accessing memory, but this is OK
* because we do not write to any memory gcc knows about, so there
* are no aliasing issues.
*
* WARNING: If you modify this macro at all, verify that the
* __check_align_* macros still work.
*/
#define __put_user_asm(x, addr, err, align, insn) \
__asm__ __volatile__( \
__check_align_##align \
"1: "insn" %1, %2, 0 \n" \
"2: \n" \
" .section .fixup,\"ax\" \n" \
" .align 4 \n" \
"4: \n" \
" .long 2b \n" \
"5: \n" \
" l32r %2, 4b \n" \
" movi %0, %3 \n" \
" jx %2 \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" .long 1b, 5b \n" \
" .previous" \
:"=r" (err) \
:"r" ((int)(x)), "r" (addr), "i" (-EFAULT), "0" (err))
#define __get_user_nocheck(x,ptr,size) \
({ \
long __gu_err, __gu_val; \
__get_user_size(__gu_val,(ptr),(size),__gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
#define __get_user_check(x,ptr,size) \
({ \
long __gu_err = -EFAULT, __gu_val = 0; \
const __typeof__(*(ptr)) *__gu_addr = (ptr); \
if (access_ok(VERIFY_READ,__gu_addr,size)) \
__get_user_size(__gu_val,__gu_addr,(size),__gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
extern long __get_user_bad(void);
#define __get_user_size(x,ptr,size,retval) \
do { \
retval = 0; \
switch (size) { \
case 1: __get_user_asm(x,ptr,retval,1,"l8ui"); break; \
case 2: __get_user_asm(x,ptr,retval,2,"l16ui"); break; \
case 4: __get_user_asm(x,ptr,retval,4,"l32i"); break; \
case 8: retval = __copy_from_user(&x,ptr,8); break; \
default: (x) = __get_user_bad(); \
} \
} while (0)
/*
* WARNING: If you modify this macro at all, verify that the
* __check_align_* macros still work.
*/
#define __get_user_asm(x, addr, err, align, insn) \
__asm__ __volatile__( \
__check_align_##align \
"1: "insn" %1, %2, 0 \n" \
"2: \n" \
" .section .fixup,\"ax\" \n" \
" .align 4 \n" \
"4: \n" \
" .long 2b \n" \
"5: \n" \
" l32r %2, 4b \n" \
" movi %1, 0 \n" \
" movi %0, %3 \n" \
" jx %2 \n" \
" .previous \n" \
" .section __ex_table,\"a\" \n" \
" .long 1b, 5b \n" \
" .previous" \
:"=r" (err), "=r" (x) \
:"r" (addr), "i" (-EFAULT), "0" (err))
/*
* Copy to/from user space
*/
/*
* We use a generic, arbitrary-sized copy subroutine. The Xtensa
* architecture would cause heavy code bloat if we tried to inline
* these functions and provide __constant_copy_* equivalents like the
* i386 versions. __xtensa_copy_user is quite efficient. See the
* .fixup section of __xtensa_copy_user for a discussion on the
* X_zeroing equivalents for Xtensa.
*/
extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n);
#define __copy_user(to,from,size) __xtensa_copy_user(to,from,size)
static inline unsigned long
__generic_copy_from_user_nocheck(void *to, const void *from, unsigned long n)
{
return __copy_user(to,from,n);
}
static inline unsigned long
__generic_copy_to_user_nocheck(void *to, const void *from, unsigned long n)
{
return __copy_user(to,from,n);
}
static inline unsigned long
__generic_copy_to_user(void *to, const void *from, unsigned long n)
{
prefetch(from);
if (access_ok(VERIFY_WRITE, to, n))
return __copy_user(to,from,n);
return n;
}
static inline unsigned long
__generic_copy_from_user(void *to, const void *from, unsigned long n)
{
prefetchw(to);
if (access_ok(VERIFY_READ, from, n))
return __copy_user(to,from,n);
else
memset(to, 0, n);
return n;
}
#define copy_to_user(to,from,n) __generic_copy_to_user((to),(from),(n))
#define copy_from_user(to,from,n) __generic_copy_from_user((to),(from),(n))
#define __copy_to_user(to,from,n) __generic_copy_to_user_nocheck((to),(from),(n))
#define __copy_from_user(to,from,n) __generic_copy_from_user_nocheck((to),(from),(n))
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user
/*
* We need to return the number of bytes not cleared. Our memset()
* returns zero if a problem occurs while accessing user-space memory.
* In that event, return no memory cleared. Otherwise, zero for
* success.
*/
static inline unsigned long
__xtensa_clear_user(void *addr, unsigned long size)
{
if ( ! memset(addr, 0, size) )
return size;
return 0;
}
static inline unsigned long
clear_user(void *addr, unsigned long size)
{
if (access_ok(VERIFY_WRITE, addr, size))
return __xtensa_clear_user(addr, size);
return size ? -EFAULT : 0;
}
#define __clear_user __xtensa_clear_user
extern long __strncpy_user(char *, const char *, long);
#define __strncpy_from_user __strncpy_user
static inline long
strncpy_from_user(char *dst, const char *src, long count)
{
if (access_ok(VERIFY_READ, src, 1))
return __strncpy_from_user(dst, src, count);
return -EFAULT;
}
#define strlen_user(str) strnlen_user((str), TASK_SIZE - 1)
/*
* Return the size of a string (including the ending 0!)
*/
extern long __strnlen_user(const char *, long);
static inline long strnlen_user(const char *str, long len)
{
unsigned long top = __kernel_ok ? ~0UL : TASK_SIZE - 1;
if ((unsigned long)str > top)
return 0;
return __strnlen_user(str, len);
}
struct exception_table_entry
{
unsigned long insn, fixup;
};
/* Returns 0 if exception not found and fixup.unit otherwise. */
extern unsigned long search_exception_table(unsigned long addr);
extern void sort_exception_table(void);
/* Returns the new pc */
#define fixup_exception(map_reg, fixup_unit, pc) \
({ \
fixup_unit; \
})
#endif /* __ASSEMBLY__ */
#endif /* _XTENSA_UACCESS_H */
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