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OpenCloudOS-Kernel
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sparc: Increase portability of strncpy_from_user() implementation. 

Hide details of maximum user address calculation in a new
asm/uaccess.h interface named user_addr_max().

Provide little-endian implementation in find_zero(), which should work
but can probably be improved.

Abstrace alignment check behind IS_UNALIGNED() macro.

Kill double-semicolon, noticed by David Howells.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2012-05-23 19:56:06 -07:00
parent 4efcac3a24
commit 35c9646062
2 changed files with 30 additions and 5 deletions
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3
arch/sparc/include/asm/uaccess.h
View File

@ -6,6 +6,9 @@
#include <asm/uaccess_32.h>
#endif
#define user_addr_max() \
(segment_eq(get_fs(), USER_DS) ? STACK_TOP : ~0UL)
extern long strncpy_from_user(char *dest, const char __user *src, long count);
#endif

32
arch/sparc/lib/usercopy.c
View File

@ -3,6 +3,8 @@
#include <linux/errno.h>
#include <linux/bug.h>
#include <asm/byteorder.h>
void copy_from_user_overflow(void)
{
WARN(1, "Buffer overflow detected!\n");
@ -14,6 +16,8 @@ EXPORT_SYMBOL(copy_from_user_overflow);
static inline long find_zero(unsigned long mask)
{
long byte = 0;
#ifdef __BIG_ENDIAN
#ifdef CONFIG_64BIT
if (mask >> 32)
mask >>= 32;
@ -25,8 +29,28 @@ static inline long find_zero(unsigned long mask)
else
byte += 2;
return (mask >> 8) ? byte : byte + 1;
#else
#ifdef CONFIG_64BIT
if (!((unsigned int) mask)) {
mask >>= 32;
byte = 4;
}
#endif
if (!(mask & 0xffff)) {
mask >>= 16;
byte += 2;
}
return (mask & 0xff) ? byte : byte + 1;
#endif
}
#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
#define IS_UNALIGNED(src, dst) 0
#else
#define IS_UNALIGNED(src, dst) \
(((long) dst | (long) src) & (sizeof(long) - 1))
#endif
/*
* Do a strncpy, return length of string without final '\0'.
* 'count' is the user-supplied count (return 'count' if we
@ -46,7 +70,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
if (max > count)
max = count;
if (((long) dst | (long) src) & (sizeof(long) - 1))
if (IS_UNALIGNED(src, dst))
goto byte_at_a_time;
while (max >= sizeof(unsigned long)) {
@ -59,7 +83,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
v = (c + high_bits) & ~rhs;
*(unsigned long *)(dst+res) = c;
if (v) {
v = (c & low_bits) + low_bits;;
v = (c & low_bits) + low_bits;
v = ~(v | rhs);
return res + find_zero(v);
}
@ -119,9 +143,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
if (unlikely(count <= 0))
return 0;
max_addr = ~0UL;
if (likely(segment_eq(get_fs(), USER_DS)))
max_addr = STACK_TOP;
max_addr = user_addr_max();
src_addr = (unsigned long)src;
if (likely(src_addr < max_addr)) {
unsigned long max = max_addr - src_addr;