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sparc: Increase portability of strncpy_from_user() implementation.

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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> #include <asm/uaccess_32.h>
#endif #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); extern long strncpy_from_user(char *dest, const char __user *src, long count);
#endif #endif

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

@ -3,6 +3,8 @@
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/bug.h> #include <linux/bug.h>
#include <asm/byteorder.h>
void copy_from_user_overflow(void) void copy_from_user_overflow(void)
{ {
WARN(1, "Buffer overflow detected!\n"); WARN(1, "Buffer overflow detected!\n");
@ -14,6 +16,8 @@ EXPORT_SYMBOL(copy_from_user_overflow);
static inline long find_zero(unsigned long mask) static inline long find_zero(unsigned long mask)
{ {
long byte = 0; long byte = 0;
#ifdef __BIG_ENDIAN
#ifdef CONFIG_64BIT #ifdef CONFIG_64BIT
if (mask >> 32) if (mask >> 32)
mask >>= 32; mask >>= 32;
@ -25,7 +29,27 @@ static inline long find_zero(unsigned long mask)
else else
byte += 2; byte += 2;
return (mask >> 8) ? byte : byte + 1; 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'. * Do a strncpy, return length of string without final '\0'.
@ -46,7 +70,7 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
if (max > count) if (max > count)
max = count; max = count;
if (((long) dst | (long) src) & (sizeof(long) - 1)) if (IS_UNALIGNED(src, dst))
goto byte_at_a_time; goto byte_at_a_time;
while (max >= sizeof(unsigned long)) { 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; v = (c + high_bits) & ~rhs;
*(unsigned long *)(dst+res) = c; *(unsigned long *)(dst+res) = c;
if (v) { if (v) {
v = (c & low_bits) + low_bits;; v = (c & low_bits) + low_bits;
v = ~(v | rhs); v = ~(v | rhs);
return res + find_zero(v); 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)) if (unlikely(count <= 0))
return 0; return 0;
max_addr = ~0UL; max_addr = user_addr_max();
if (likely(segment_eq(get_fs(), USER_DS)))
max_addr = STACK_TOP;
src_addr = (unsigned long)src; src_addr = (unsigned long)src;
if (likely(src_addr < max_addr)) { if (likely(src_addr < max_addr)) {
unsigned long max = max_addr - src_addr; unsigned long max = max_addr - src_addr;