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Commit a00d0eee authored by Sanrio Alvares's avatar Sanrio Alvares
Browse files

lib: align source before using optimized implementation 



If the source is at the boundary of the VMA, loading one word at a
time can cause an alignment fault when the adjacent VMA is IO mapped.
Do byte-by-byte copy until source aligns to 8 bytes and then continue
with optimized version.

CRs-Fixed: 973724
Change-Id: I05e085597c58169fc6e275508a907029b9c7ec64
Signed-off-by: default avatarSanrio Alvares <salvares@codeaurora.org>
parent 67928fab

lib/strncpy_from_user.c

+17 −0
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ 
	(((long) dst | (long) src) & (sizeof(long) - 1))

#endif



#define CHECK_ALIGN(v, a) ((((unsigned long)(v)) & ((a) - 1)) == 0)



/*

 * Do a strncpy, return length of string without final '\0'.

 * 'count' is the user-supplied count (return 'count' if we
@@ -34,6 +36,21 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long 
	if (IS_UNALIGNED(src, dst))

		goto byte_at_a_time;



	/* Copy a byte at a time until we align to 8 bytes */

	while (max && (!CHECK_ALIGN(src + res, 8))) {

		char c;

		int ret;



		ret = __get_user(c, src + res);

		if (ret)

			return -ret;

		dst[res] = c;

		if (!c)

			return res;

		res++;

		max--;

	}



	while (max >= sizeof(unsigned long)) {

		unsigned long c, data;