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authorDavid S. Miller <davem@davemloft.net>2012-05-23 19:56:06 -0700
committerDavid S. Miller <davem@davemloft.net>2012-05-24 13:04:24 -0700
commit35c9646062eba15351c6d64ea0c02176e5cb66ac (patch)
tree46b29964dfbf21e6757b5ab629c6f748897d34e5
parent4efcac3a244de86593a82ca4ed945e839eb4c5af (diff)
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>
-rw-r--r--arch/sparc/include/asm/uaccess.h3
-rw-r--r--arch/sparc/lib/usercopy.c32
2 files changed, 30 insertions, 5 deletions
diff --git a/arch/sparc/include/asm/uaccess.h b/arch/sparc/include/asm/uaccess.h
index 42a28cfd941..20c2acb0633 100644
--- a/arch/sparc/include/asm/uaccess.h
+++ b/arch/sparc/include/asm/uaccess.h
@@ -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
diff --git a/arch/sparc/lib/usercopy.c b/arch/sparc/lib/usercopy.c
index 87f96453403..f61ed820cb6 100644
--- a/arch/sparc/lib/usercopy.c
+++ b/arch/sparc/lib/usercopy.c
@@ -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;