From: Hacksaw <hacksaw@hacksaw.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tomko <tomko@haha.com>, Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Why system call need to copy the date from the userspace before using it
Date: Wed, 13 Apr 2005 07:59:54 -0400 [thread overview]
Message-ID: <200504131159.j3DBxsoa010918@hacksaw.org> (raw)
In-Reply-To: Your message of "Wed, 13 Apr 2005 21:33:27 +1000." <1113392007.5516.26.camel@gaston>
>>Why not use it directly
>Some of these reasons are:
It seems like you gave reason why userland pointers shouldn't be trusted, not
why userland data should be copied into kernel land. All the problems you
mentioned would have to be solved by the kernel regardless of copying the data
around.
Ummm... Except for the who's mapped now problem. That's pretty weird. I guess
that's something that comes with trying to use tons of RAM in a 32 bit system.
I thought the big issue was the need to lock the page(s) during the call, and
maybe some tricky races which made the idea difficult.
--
The key is realizing the whole world is stupid and being happy anyway
http://www.hacksaw.org -- http://www.privatecircus.com -- KB1FVD
next prev parent reply other threads:[~2005-04-13 12:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-13 4:21 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
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 [this message]
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
2005-04-13 6:48 Vadim Lobanov
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