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/* -*- linux-c -*-
* Copy from user space functions
* Copyright (C) 2005-2008 Red Hat Inc.
* Copyright (C) 2005 Intel Corporation.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _COPY_C_ /* -*- linux-c -*- */
#define _COPY_C_
#include "string.c"
/** @file copy.c
* @brief Functions to copy from user space.
*/
/** @addtogroup copy Functions to copy from user space.
* Functions to copy from user space.
* None of these functions will sleep (for example to allow pages
* to be swapped in). It is possible (although rare) that the data
* in user space will not present and these functions will return an error.
* @{
*/
/** Safely read from userspace or kernelspace.
* On success, returns 0. Returns -EFAULT on error.
*
* This uses __get_user() to read from userspace or
* kernelspace. Will not sleep or cause pagefaults when
* called from within a kprobe context.
*
* @param segment . KERNEL_DS for kernel access
* USER_DS for userspace.
*/
#define _stp_read_address(x, ptr, segment) \
({ \
long ret; \
mm_segment_t ofs = get_fs(); \
set_fs(segment); \
ret = __stp_get_user(x, ptr); \
set_fs(ofs); \
ret; \
})
static long __stp_strncpy_from_user(char *dst, const char __user *src, long count);
#if defined (__i386__)
#define __stp_strncpy_from_user(dst,src,count,res) \
do { \
int __d0, __d1, __d2; \
__asm__ __volatile__( \
" testl %1,%1\n" \
" jz 2f\n" \
"0: lodsb\n" \
" stosb\n" \
" testb %%al,%%al\n" \
" jz 1f\n" \
" decl %1\n" \
" jnz 0b\n" \
"1: subl %1,%0\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: movl %5,%0\n" \
" jmp 2b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 4\n" \
" .long 0b,3b\n" \
".previous" \
: "=d"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \
"=&D" (__d2) \
: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
: "memory"); \
} while (0)
#elif defined (__x86_64__)
#define __stp_strncpy_from_user(dst,src,count,res) \
do { \
long __d0, __d1, __d2; \
__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" \
".section __ex_table,\"a\"\n" \
" .align 8\n" \
" .quad 0b,3b\n" \
".previous" \
: "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \
"=&D" (__d2) \
: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
: "memory"); \
} while (0)
#elif defined (__powerpc__) || defined (__ia64__) || defined (__arm__)
#define __stp_strncpy_from_user(dst,src,count,res) \
do { res = __strncpy_from_user(dst, src, count); } while(0)
#elif defined (__s390__) || defined (__s390x__)
#define __stp_strncpy_from_user(dst,src,count,res) \
do { res = strncpy_from_user(dst, src, count); } while(0)
#endif
/** Copy a NULL-terminated string from userspace.
* On success, returns the length of the string (not including the trailing
* NULL).
*
* If access to userspace fails, returns -EFAULT (some data may have been
* copied).
* @param dst Destination address, in kernel space. This buffer must be at
* least <i>count</i> bytes long.
* @param src Source address, in user space.
* @param count Maximum number of bytes to copy, including the trailing NULL.
*
* If <i>count</i> is smaller than the length of the string, copies
* <i>count</i> bytes and returns <i>count</i>.
*/
static long _stp_strncpy_from_user(char *dst, const char __user *src, long count)
{
long res = -EFAULT;
if (access_ok(VERIFY_READ, src, count))
__stp_strncpy_from_user(dst, src, count, res);
return res;
}
/** Copy a block of data from user space.
*
* If some data could not be copied, this function will pad the copied
* data to the requested size using zero bytes.
* @param dst Destination address, in kernel space.
* @param src Source address, in user space.
* @param count Number of bytes to copy.
* @return number of bytes that could not be copied. On success,
* this will be zero.
*
*/
static unsigned long _stp_copy_from_user(char *dst, const char __user *src, unsigned long count)
{
if (count) {
if (access_ok(VERIFY_READ, src, count))
count = __copy_from_user_inatomic(dst, src, count);
else
memset(dst, 0, count);
}
return count;
}
/** @} */
#endif /* _COPY_C_ */
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