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/*
* User address space access functions.
*
* Copyright 1997 Andi Kleen <ak@muc.de>
* Copyright 1997 Linus Torvalds
* Copyright 2002 Andi Kleen <ak@suse.de>
*/
#include <linux/module.h>
#include <asm/uaccess.h>
/*
* Copy a null terminated string from userspace.
*/
#define __do_strncpy_from_user(dst,src,count,res) \
do { \
long __d0, __d1, __d2; \
might_fault(); \
__asm__ __volatile__( \
" testq %1,%1\n" \
" jz 2f\n" \
"0: lodsb\n" \
" stosb\n" \
" testb %%al,%%al\n" \
" jz 1f\n" \
" decq %1\n" \
" jnz 0b\n" \
"1: subq %1,%0\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: movq %5,%0\n" \
" jmp 2b\n" \
".previous\n" \
_ASM_EXTABLE(0b,3b) \
: "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \
"=&D" (__d2) \
: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
: "memory"); \
} while (0)
long
__strncpy_from_user(char *dst, const char __user *src, long count)
{
long res;
__do_strncpy_from_user(dst, src, count, res);
return res;
}
EXPORT_SYMBOL(__strncpy_from_user);
long
strncpy_from_user(char *dst, const char __user *src, long count)
{
long res = -EFAULT;
if (access_ok(VERIFY_READ, src, 1))
return __strncpy_from_user(dst, src, count);
return res;
}
EXPORT_SYMBOL(strncpy_from_user);
/*
* Zero Userspace
*/
unsigned long __clear_user(void __user *addr, unsigned long size)
{
long __d0;
might_fault();
/* no memory constraint because it doesn't change any memory gcc knows
about */
asm volatile(
" testq %[size8],%[size8]\n"
" jz 4f\n"
"0: movq %[zero],(%[dst])\n"
" addq %[eight],%[dst]\n"
" decl %%ecx ; jnz 0b\n"
"4: movq %[size1],%%rcx\n"
" testl %%ecx,%%ecx\n"
" jz 2f\n"
"1: movb %b[zero],(%[dst])\n"
" incq %[dst]\n"
" decl %%ecx ; jnz 1b\n"
"2:\n"
".section .fixup,\"ax\"\n"
"3: lea 0(%[size1],%[size8],8),%[size8]\n"
" jmp 2b\n"
".previous\n"
_ASM_EXTABLE(0b,3b)
_ASM_EXTABLE(1b,2b)
: [size8] "=c"(size), [dst] "=&D" (__d0)
: [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
[zero] "r" (0UL), [eight] "r" (8UL));
return size;
}
EXPORT_SYMBOL(__clear_user);
unsigned long clear_user(void __user *to, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
return __clear_user(to, n);
return n;
}
EXPORT_SYMBOL(clear_user);
/*
* Return the size of a string (including the ending 0)
*
* Return 0 on exception, a value greater than N if too long
*/
long __strnlen_user(const char __user *s, long n)
{
long res = 0;
char c;
while (1) {
if (res>n)
return n+1;
if (__get_user(c, s))
return 0;
if (!c)
return res+1;
res++;
s++;
}
}
EXPORT_SYMBOL(__strnlen_user);
long strnlen_user(const char __user *s, long n)
{
if (!access_ok(VERIFY_READ, s, n))
return 0;
return __strnlen_user(s, n);
}
EXPORT_SYMBOL(strnlen_user);
long strlen_user(const char __user *s)
{
long res = 0;
char c;
for (;;) {
if (get_user(c, s))
return 0;
if (!c)
return res+1;
res++;
s++;
}
}
EXPORT_SYMBOL(strlen_user);
unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
{
if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
return copy_user_generic((__force void *)to, (__force void *)from, len);
}
return len;
}
EXPORT_SYMBOL(copy_in_user);
/*
* Try to copy last bytes and clear the rest if needed.
* Since protection fault in copy_from/to_user is not a normal situation,
* it is not necessary to optimize tail handling.
*/
unsigned long
copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
{
char c;
unsigned zero_len;
for (; len; --len) {
if (__get_user_nocheck(c, from++, sizeof(char)))
break;
if (__put_user_nocheck(c, to++, sizeof(char)))
break;
}
for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
if (__put_user_nocheck(c, to++, sizeof(char)))
break;
return len;
}
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