1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
5 * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 #include <linux/uaccess.h>
9 #include <linux/module.h>
10 #include <wrapper/uaccess.h>
11 #include <probes/lttng-probe-user.h>
13 #define LTTNG_MAX_USER_STRING_LEN 1048576 /* 1MB */
16 * Calculate string length. Include final null terminating character if there is
17 * one, or ends at first fault. Disabling page faults ensures that we can safely
18 * call this from pretty much any context, including those where the caller
19 * holds mmap_sem, or any lock which nests in mmap_sem.
21 long lttng_strlen_user_inatomic(const char *addr
)
33 if (unlikely(!lttng_access_ok(VERIFY_READ
,
34 (__force
const char __user
*) addr
,
37 ret
= __copy_from_user_inatomic(&v
,
38 (__force
const char __user
*)(addr
),
40 if (unlikely(ret
> 0))
43 if (unlikely(count
> LTTNG_MAX_USER_STRING_LEN
))
52 EXPORT_SYMBOL_GPL(lttng_strlen_user_inatomic
);