linux-kernel - Re: How to avoid data copies in a driver ?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 15 May 2008 09:59:01 -0400
From:	lsorense@...lub.uwaterloo.ca (Lennart Sorensen)
To:	Francis Moreau <francis.moro@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: How to avoid data copies in a driver ?

On Thu, May 15, 2008 at 09:44:37AM +0200, Francis Moreau wrote:
> So I would need to map this pointer into the kernel space, then fill it, take
> care of cache coherency, unmap the kernel pointer.
> 
> Do you have any example of that in the kernel tree ?

I was asking if that would work.  Does the to_user and from_user work on
a pointer from user space if that pointer points at a memory mapped
file?

> BTW, data are received in interrupt context. Is it safe to put them in mapped
> memory  (can I have page fault ?) in this context ?

Oh I thought you just wanted user space to be able to ask for a chunk of
data.  I wouldn't want to write to a file in an interrupt handler.
Compared to the disk I/O a memory copy sounds rather insignificant to
the overall process.

-- 
Len Sorensen
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/