Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d7b788cd authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/uaccess: shorten strncpy_from_user/strnlen_user 



Always stay within page boundaries when copying from user within
strlen_user_mvcos()/strncpy_from_user_mvcos(). This allows to
shorten the code a bit and may prevent unnecessary faults, since
we copy quite large amounts of memory to kernel space.

Also directly call the mvcos variants of copy_from_user() to
avoid indirect branches.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ea4da6ea

arch/s390/lib/uaccess_mvcos.c

+12 −12
Original line number Original line Diff line number Diff line
@@ -162,19 +162,19 @@ static size_t clear_user_mvcos(size_t size, void __user *to) 




static size_t strnlen_user_mvcos(size_t count, const char __user *src)

static size_t strnlen_user_mvcos(size_t count, const char __user *src)

{

{

	size_t done, len, offset, len_str;

	char buf[256];

	char buf[256];

	int rc;

	size_t done, len, len_str;





	done = 0;

	done = 0;

	do {

	do {

		len = min(count - done, (size_t) 256);

		offset = (size_t)src & ~PAGE_MASK;

		rc = uaccess.copy_from_user(len, src + done, buf);

		len = min(256UL, PAGE_SIZE - offset);

		if (unlikely(rc == len))

		len = min(count - done, len);

		if (copy_from_user_mvcos(len, src, buf))

			return 0;

			return 0;

		len -= rc;

		len_str = strnlen(buf, len);

		len_str = strnlen(buf, len);

		done += len_str;

		done += len_str;

		src += len_str;

	} while ((len_str == len) && (done < count));

	} while ((len_str == len) && (done < count));

	return done + 1;

	return done + 1;

}

}
@@ -182,18 +182,18 @@ static size_t strnlen_user_mvcos(size_t count, const char __user *src) 
static size_t strncpy_from_user_mvcos(size_t count, const char __user *src,

static size_t strncpy_from_user_mvcos(size_t count, const char __user *src,

				      char *dst)

				      char *dst)

{

{

	int rc;

	size_t done, len, offset, len_str;

	size_t done, len, len_str;





	done = 0;

	done = 0;

	do {

	do {

		len = min(count - done, (size_t) 4096);

		offset = (size_t)src & ~PAGE_MASK;

		rc = uaccess.copy_from_user(len, src + done, dst);

		len = min(count - done, PAGE_SIZE - offset);

		if (unlikely(rc == len))

		if (copy_from_user_mvcos(len, src, dst))

			return -EFAULT;

			return -EFAULT;

		len -= rc;

		len_str = strnlen(dst, len);

		len_str = strnlen(dst, len);

		done += len_str;

		done += len_str;

		src += len_str;

		dst += len_str;

	} while ((len_str == len) && (done < count));

	} while ((len_str == len) && (done < count));

	return done;

	return done;

}

}