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linux/include/asm-powerpc/uaccess.h
Paul Mackerras 6bfd93c32a powerpc: Fix incorrect might_sleep in __get_user/__put_user on kernel addresses 
We have a case where __get_user and __put_user can validly be used
on kernel addresses in interrupt context - namely, the alignment
exception handler, as our get/put_unaligned just do a single access
and rely on the alignment exception handler to fix things up in the
rare cases where the cpu can't handle it in hardware.  Thus we can
get alignment exceptions in the network stack at interrupt level.
The alignment exception handler does a __get_user to read the
instruction and blows up in might_sleep().

Since a __get_user on a kernel address won't actually ever sleep,
this makes the might_sleep conditional on the address being less
than PAGE_OFFSET.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-05-03 23:06:46 +10:00

472 lines
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C
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#ifndef _ARCH_POWERPC_UACCESS_H
#define _ARCH_POWERPC_UACCESS_H
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/errno.h>
#include <asm/processor.h>
#include <asm/page.h>
#define VERIFY_READ 0
#define VERIFY_WRITE 1
/*
* 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, these macros are grossly misnamed.
*
* The fs/ds values are now the highest legal address in the "segment".
* This simplifies the checking in the routines below.
*/
#define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
#define KERNEL_DS MAKE_MM_SEG(~0UL)
#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
#define USER_DS MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
#else
#define USER_DS MAKE_MM_SEG(TASK_SIZE - 1)
#endif
#define get_ds() (KERNEL_DS)
#define get_fs() (current->thread.fs)
#define set_fs(val) (current->thread.fs = (val))
#define segment_eq(a, b) ((a).seg == (b).seg)
#ifdef __powerpc64__
/*
* This check is sufficient because there is a large enough
* gap between user addresses and the kernel addresses
*/
#define __access_ok(addr, size, segment) \
(((addr) <= (segment).seg) && ((size) <= (segment).seg))
#else
#define __access_ok(addr, size, segment) \
(((addr) <= (segment).seg) && \
(((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
#endif
#define access_ok(type, addr, size) \
(__chk_user_ptr(addr), \
__access_ok((__force unsigned long)(addr), (size), get_fs()))
/*
* The exception table consists of pairs of addresses: the first is the
* address of an instruction that is allowed to fault, and the second is
* the address at which the program should continue. No registers are
* modified, so it is entirely up to the continuation code to figure out
* what to do.
*
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
* we don't even have to jump over them. Further, they do not intrude
* on our cache or tlb entries.
*/
struct exception_table_entry {
unsigned long insn;
unsigned long fixup;
};
/*
* 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 ugliness from the user.
*
* 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).
*
* As we use the same address space for kernel and user data on the
* PowerPC, we can just do these as direct assignments. (Of course, the
* exception handling means that it's no longer "just"...)
*
* The "user64" versions of the user access functions are versions that
* allow access of 64-bit data. The "get_user" functions do not
* properly handle 64-bit data because the value gets down cast to a long.
* The "put_user" functions already handle 64-bit data properly but we add
* "user64" versions for completeness
*/
#define get_user(x, ptr) \
__get_user_check((x), (ptr), sizeof(*(ptr)))
#define put_user(x, ptr) \
__put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
#define __get_user(x, ptr) \
__get_user_nocheck((x), (ptr), sizeof(*(ptr)))
#define __put_user(x, ptr) \
__put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
#ifndef __powerpc64__
#define __get_user64(x, ptr) \
__get_user64_nocheck((x), (ptr), sizeof(*(ptr)))
#define __put_user64(x, ptr) __put_user(x, ptr)
#endif
#define __get_user_unaligned __get_user
#define __put_user_unaligned __put_user
extern long __put_user_bad(void);
/*
* 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.
*/
#define __put_user_asm(x, addr, err, op) \
__asm__ __volatile__( \
"1: " op " %1,0(%2) # put_user\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: li %0,%3\n" \
" b 2b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .balign %5\n" \
PPC_LONG "1b,3b\n" \
".previous" \
: "=r" (err) \
: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
"i"(sizeof(unsigned long)))
#ifdef __powerpc64__
#define __put_user_asm2(x, ptr, retval) \
__put_user_asm(x, ptr, retval, "std")
#else /* __powerpc64__ */
#define __put_user_asm2(x, addr, err) \
__asm__ __volatile__( \
"1: stw %1,0(%2)\n" \
"2: stw %1+1,4(%2)\n" \
"3:\n" \
".section .fixup,\"ax\"\n" \
"4: li %0,%3\n" \
" b 3b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .balign %5\n" \
PPC_LONG "1b,4b\n" \
PPC_LONG "2b,4b\n" \
".previous" \
: "=r" (err) \
: "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
"i"(sizeof(unsigned long)))
#endif /* __powerpc64__ */
#define __put_user_size(x, ptr, size, retval) \
do { \
retval = 0; \
switch (size) { \
case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
case 8: __put_user_asm2(x, ptr, retval); break; \
default: __put_user_bad(); \
} \
} while (0)
#define __put_user_nocheck(x, ptr, size) \
({ \
long __pu_err; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
if (!is_kernel_addr((unsigned long)__pu_addr)) \
might_sleep(); \
__chk_user_ptr(ptr); \
__put_user_size((x), __pu_addr, (size), __pu_err); \
__pu_err; \
})
#define __put_user_check(x, ptr, size) \
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
might_sleep(); \
if (access_ok(VERIFY_WRITE, __pu_addr, size)) \
__put_user_size((x), __pu_addr, (size), __pu_err); \
__pu_err; \
})
extern long __get_user_bad(void);
#define __get_user_asm(x, addr, err, op) \
__asm__ __volatile__( \
"1: "op" %1,0(%2) # get_user\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: li %0,%3\n" \
" li %1,0\n" \
" b 2b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .balign %5\n" \
PPC_LONG "1b,3b\n" \
".previous" \
: "=r" (err), "=r" (x) \
: "b" (addr), "i" (-EFAULT), "0" (err), \
"i"(sizeof(unsigned long)))
#ifdef __powerpc64__
#define __get_user_asm2(x, addr, err) \
__get_user_asm(x, addr, err, "ld")
#else /* __powerpc64__ */
#define __get_user_asm2(x, addr, err) \
__asm__ __volatile__( \
"1: lwz %1,0(%2)\n" \
"2: lwz %1+1,4(%2)\n" \
"3:\n" \
".section .fixup,\"ax\"\n" \
"4: li %0,%3\n" \
" li %1,0\n" \
" li %1+1,0\n" \
" b 3b\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .balign %5\n" \
PPC_LONG "1b,4b\n" \
PPC_LONG "2b,4b\n" \
".previous" \
: "=r" (err), "=&r" (x) \
: "b" (addr), "i" (-EFAULT), "0" (err), \
"i"(sizeof(unsigned long)))
#endif /* __powerpc64__ */
#define __get_user_size(x, ptr, size, retval) \
do { \
retval = 0; \
__chk_user_ptr(ptr); \
if (size > sizeof(x)) \
(x) = __get_user_bad(); \
switch (size) { \
case 1: __get_user_asm(x, ptr, retval, "lbz"); break; \
case 2: __get_user_asm(x, ptr, retval, "lhz"); break; \
case 4: __get_user_asm(x, ptr, retval, "lwz"); break; \
case 8: __get_user_asm2(x, ptr, retval); break; \
default: (x) = __get_user_bad(); \
} \
} while (0)
#define __get_user_nocheck(x, ptr, size) \
({ \
long __gu_err; \
unsigned long __gu_val; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
if (!is_kernel_addr((unsigned long)__gu_addr)) \
might_sleep(); \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
#ifndef __powerpc64__
#define __get_user64_nocheck(x, ptr, size) \
({ \
long __gu_err; \
long long __gu_val; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
if (!is_kernel_addr((unsigned long)__gu_addr)) \
might_sleep(); \
__get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
(x) = (__typeof__(*(ptr)))__gu_val; \
__gu_err; \
})
#endif /* __powerpc64__ */
#define __get_user_check(x, ptr, size) \
({ \
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
might_sleep(); \
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; \
})
/* more complex routines */
extern unsigned long __copy_tofrom_user(void __user *to,
const void __user *from, unsigned long size);
#ifndef __powerpc64__
extern inline unsigned long copy_from_user(void *to,
const void __user *from, unsigned long n)
{
unsigned long over;
if (access_ok(VERIFY_READ, from, n))
return __copy_tofrom_user((__force void __user *)to, from, n);
if ((unsigned long)from < TASK_SIZE) {
over = (unsigned long)from + n - TASK_SIZE;
return __copy_tofrom_user((__force void __user *)to, from,
n - over) + over;
}
return n;
}
extern inline unsigned long copy_to_user(void __user *to,
const void *from, unsigned long n)
{
unsigned long over;
if (access_ok(VERIFY_WRITE, to, n))
return __copy_tofrom_user(to, (__force void __user *)from, n);
if ((unsigned long)to < TASK_SIZE) {
over = (unsigned long)to + n - TASK_SIZE;
return __copy_tofrom_user(to, (__force void __user *)from,
n - over) + over;
}
return n;
}
#else /* __powerpc64__ */
#define __copy_in_user(to, from, size) \
__copy_tofrom_user((to), (from), (size))
extern unsigned long copy_from_user(void *to, const void __user *from,
unsigned long n);
extern unsigned long copy_to_user(void __user *to, const void *from,
unsigned long n);
extern unsigned long copy_in_user(void __user *to, const void __user *from,
unsigned long n);
#endif /* __powerpc64__ */
static inline unsigned long __copy_from_user_inatomic(void *to,
const void __user *from, unsigned long n)
{
if (__builtin_constant_p(n) && (n <= 8)) {
unsigned long ret;
switch (n) {
case 1:
__get_user_size(*(u8 *)to, from, 1, ret);
break;
case 2:
__get_user_size(*(u16 *)to, from, 2, ret);
break;
case 4:
__get_user_size(*(u32 *)to, from, 4, ret);
break;
case 8:
__get_user_size(*(u64 *)to, from, 8, ret);
break;
}
if (ret == 0)
return 0;
}
return __copy_tofrom_user((__force void __user *)to, from, n);
}
static inline unsigned long __copy_to_user_inatomic(void __user *to,
const void *from, unsigned long n)
{
if (__builtin_constant_p(n) && (n <= 8)) {
unsigned long ret;
switch (n) {
case 1:
__put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
break;
case 2:
__put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
break;
case 4:
__put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
break;
case 8:
__put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
break;
}
if (ret == 0)
return 0;
}
return __copy_tofrom_user(to, (__force const void __user *)from, n);
}
static inline unsigned long __copy_from_user(void *to,
const void __user *from, unsigned long size)
{
might_sleep();
return __copy_from_user_inatomic(to, from, size);
}
static inline unsigned long __copy_to_user(void __user *to,
const void *from, unsigned long size)
{
might_sleep();
return __copy_to_user_inatomic(to, from, size);
}
extern unsigned long __clear_user(void __user *addr, unsigned long size);
static inline unsigned long clear_user(void __user *addr, unsigned long size)
{
might_sleep();
if (likely(access_ok(VERIFY_WRITE, addr, size)))
return __clear_user(addr, size);
if ((unsigned long)addr < TASK_SIZE) {
unsigned long over = (unsigned long)addr + size - TASK_SIZE;
return __clear_user(addr, size - over) + over;
}
return size;
}
extern int __strncpy_from_user(char *dst, const char __user *src, long count);
static inline long strncpy_from_user(char *dst, const char __user *src,
long count)
{
might_sleep();
if (likely(access_ok(VERIFY_READ, src, 1)))
return __strncpy_from_user(dst, src, count);
return -EFAULT;
}
/*
* Return the size of a string (including the ending 0)
*
* Return 0 for error
*/
extern int __strnlen_user(const char __user *str, long len, unsigned long top);
/*
* Returns the length of the string at str (including the null byte),
* or 0 if we hit a page we can't access,
* or something > len if we didn't find a null byte.
*
* The `top' parameter to __strnlen_user is to make sure that
* we can never overflow from the user area into kernel space.
*/
static inline int strnlen_user(const char __user *str, long len)
{
unsigned long top = current->thread.fs.seg;
if ((unsigned long)str > top)
return 0;
return __strnlen_user(str, len, top);
}
#define strlen_user(str) strnlen_user((str), 0x7ffffffe)
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ARCH_POWERPC_UACCESS_H */
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