From: Tomko <tomko@haha.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Why system call need to copy the date from the userspace before using it
Date: Thu, 14 Apr 2005 10:10:13 +0800 [thread overview]
Message-ID: <425DD105.7010304@haha.com> (raw)
In-Reply-To: <tnxd5szvsnd.fsf@arm.com>
Catalin Marinas wrote:
>Tomko <tomko@haha.com> wrote:
>
>
>>Inside the system call , the kernel often copy the data by calling
>>copy_from_user() rather than just using strcpy(), is it because the
>>memory mapping in kenel space is different from user space?
>>
>>
>
>No, it is because this function checks whether the access to the user
>space address is OK. There are situations when it can also sleep (page
>not present).
>
>
>
what u means "OK"? kernel space should have right to access any memory
address , can u expained in details what u means "OK"?
next prev parent reply other threads:[~2005-04-14 2:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-13 4:21 Why system call need to copy the date from the userspace before using it Tomko
2005-04-13 5:30 ` Vadim Lobanov
2005-04-13 10:29 ` Jan-Benedict Glaw
2005-04-13 10:43 ` Tomko
2005-04-13 11:10 ` Catalin Marinas
2005-04-14 2:10 ` Tomko [this message]
2005-04-14 2:18 ` David Schwartz
2005-04-14 14:05 ` Helge Hafting
2005-04-13 11:33 ` Benjamin Herrenschmidt
2005-04-13 11:59 ` Hacksaw
2005-04-13 12:40 ` Richard B. Johnson
2005-04-13 18:37 ` Theodore Ts'o
2005-04-13 19:20 ` Richard B. Johnson
2005-04-16 4:50 ` Hacksaw
2005-04-16 5:18 ` Vadim Lobanov
2005-04-16 8:30 ` Hacksaw
2005-04-16 19:35 ` Vadim Lobanov
2005-04-16 23:46 ` David Wagner
-- strict thread matches above, loose matches on Subject: below --
2005-04-13 6:48 Vadim Lobanov
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