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authorHeiko Carstens <heiko.carstens@de.ibm.com>2013-02-20 13:59:26 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-02-28 09:37:07 +0100
commitd7b788cd06a3080ebf0b2f5f2e008d4fda2b336e (patch)
tree69441ca08ebf084277bc3d944bdde8d0ccdb8ecb /arch/s390/lib
parentea4da6eae393dbbb26800700a38cf1b32c9109fd (diff)
downloadlinux-linaro-stable-d7b788cd06a3080ebf0b2f5f2e008d4fda2b336e.tar.gz
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: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib')
-rw-r--r--arch/s390/lib/uaccess_mvcos.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/arch/s390/lib/uaccess_mvcos.c b/arch/s390/lib/uaccess_mvcos.c
index 2443ae476e33..7f3eb3d56024 100644
--- a/arch/s390/lib/uaccess_mvcos.c
+++ b/arch/s390/lib/uaccess_mvcos.c
@@ -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)
{
+ size_t done, len, offset, len_str;
char buf[256];
- int rc;
- size_t done, len, len_str;
done = 0;
do {
- len = min(count - done, (size_t) 256);
- rc = uaccess.copy_from_user(len, src + done, buf);
- if (unlikely(rc == len))
+ offset = (size_t)src & ~PAGE_MASK;
+ len = min(256UL, PAGE_SIZE - offset);
+ len = min(count - done, len);
+ if (copy_from_user_mvcos(len, src, buf))
return 0;
- len -= rc;
len_str = strnlen(buf, len);
done += len_str;
+ src += len_str;
} while ((len_str == len) && (done < count));
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,
char *dst)
{
- int rc;
- size_t done, len, len_str;
+ size_t done, len, offset, len_str;
done = 0;
do {
- len = min(count - done, (size_t) 4096);
- rc = uaccess.copy_from_user(len, src + done, dst);
- if (unlikely(rc == len))
+ offset = (size_t)src & ~PAGE_MASK;
+ len = min(count - done, PAGE_SIZE - offset);
+ if (copy_from_user_mvcos(len, src, dst))
return -EFAULT;
- len -= rc;
len_str = strnlen(dst, len);
done += len_str;
+ src += len_str;
+ dst += len_str;
} while ((len_str == len) && (done < count));
return done;
}