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Commit 35c96460 authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parent 4efcac3a

arch/sparc/include/asm/uaccess.h

+3 −0
Original line number Diff line number Diff line
@@ -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

arch/sparc/lib/usercopy.c

+27 −5
Original line number Diff line number Diff line
@@ -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;
@@ -25,7 +29,27 @@ 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'.
@@ -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;