From: Brian Gerst <bgerst@didntduck.org>
To: "Michael S. Tsirkin" <mst@mellanox.co.il>
Cc: Christoph Hellwig <hch@infradead.org>, Andi Kleen <ak@suse.de>,
discuss@x86-64.org, linux-kernel@vger.kernel.org
Subject: Re: how to detect a 32 bit process on 64 bit kernel
Date: Mon, 13 Dec 2004 16:32:37 -0500 [thread overview]
Message-ID: <41BE0A75.3070206@didntduck.org> (raw)
In-Reply-To: <20041213195011.GA24053@mellanox.co.il>
Michael S. Tsirkin wrote:
> Hello!
> Quoting r. Christoph Hellwig (hch@infradead.org) "Re: how to detect a 32 bit process on 64 bit kernel":
>
>>>If no - would not it make a sence to add e.g. a flag in the
>>>task struct, to make it possible?
>>
>>The kernel code shouldn't know. If your driver needs this information
>>something is seriously wrong with it.
>
>
> A character driver I am working on gets passed a structure
> from user space by implementing a write file operation.
> The structure includes a pointer and so the format varies
> between a 32 and 64 bit processes.
The most portable way to do this is to have the first member of the
structure be a 32-bit value containing the size of the structure. This
can then be used to identify what the structure format is. This also
has the advantage of future-proofing the interface (add a field? no
problem, the new size can be checked for). Just be very careful that
the size from userspace is not trusted (ie. only allow known sizes).
--
Brian Gerst
next prev parent reply other threads:[~2004-12-13 21:33 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-01 7:22 f_ops flag to speed up compatible ioctls in linux kernel Michael S. Tsirkin
2004-09-01 7:32 ` viro
2004-09-01 7:44 ` Michael S. Tsirkin
2004-09-01 7:47 ` Lee Revell
2004-09-01 8:19 ` Michael S. Tsirkin
2004-09-01 15:55 ` Roland Dreier
2004-09-01 18:02 ` Chris Wright
2004-09-01 18:12 ` Roland Dreier
2004-09-01 18:31 ` viro
2004-09-01 20:54 ` Roland Dreier
[not found] ` <20040901170800.K1924@build.pdx.osdl.net>
[not found] ` <20040901190122.L1924@build.pdx.osdl.net>
2004-09-02 3:46 ` Roland Dreier
2004-09-01 18:06 ` Bill Davidsen
2004-09-01 8:30 ` Arjan van de Ven
2004-09-01 15:40 ` [PATCH] fs/compat.c: rwsem instead of BKL around ioctl32_hash_table Roland Dreier
2004-09-01 23:27 ` Andrew Morton
2004-09-02 21:14 ` Andi Kleen
2004-09-02 22:26 ` Roland Dreier
2004-09-03 14:37 ` [discuss] " Andi Kleen
2004-09-03 14:55 ` Roland Dreier
2004-09-03 15:02 ` Andi Kleen
2004-09-03 8:00 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Andi Kleen
2004-09-07 10:40 ` Michael S. Tsirkin
2004-09-07 12:14 ` Andi Kleen
2004-09-07 13:45 ` Michael S. Tsirkin
2004-09-07 14:15 ` Andi Kleen
2004-09-07 14:25 ` Michael S. Tsirkin
2004-09-07 14:29 ` Andi Kleen
2004-09-07 14:37 ` Michael S. Tsirkin
2004-09-07 14:44 ` Andi Kleen
2004-09-07 14:45 ` Michael S. Tsirkin
2004-09-07 15:10 ` Andi Kleen
2004-09-07 18:16 ` Michael S. Tsirkin
2004-09-08 6:55 ` Andi Kleen
2004-09-08 14:28 ` [patch] " Michael S. Tsirkin
2004-09-08 14:38 ` Andi Kleen
2004-09-08 14:54 ` Michael S. Tsirkin
2004-09-08 14:58 ` Andi Kleen
2004-09-12 20:05 ` Michael S. Tsirkin
2004-09-15 13:19 ` [patch] Re: [discuss] " Michael S. Tsirkin
2004-09-07 21:36 ` Is FIOQSIZE compatible? ( was Re: f_ops flag to speed up compatible ioctls in linux kernel) Michael S. Tsirkin
2004-09-08 6:54 ` Andi Kleen
2004-09-07 15:03 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Herbert Poetzl
2004-09-07 18:07 ` Michael S. Tsirkin
2004-09-09 13:54 ` Herbert Poetzl
2004-12-12 21:51 ` how to detect a 32 bit process on 64 bit kernel Michael S. Tsirkin
2004-12-12 22:01 ` Jan Engelhardt
2004-12-12 22:23 ` Christoph Hellwig
2004-12-13 19:50 ` Michael S. Tsirkin
2004-12-13 21:01 ` Jan Engelhardt
2004-12-13 21:32 ` Brian Gerst [this message]
2004-12-13 21:37 ` Michael S. Tsirkin
2004-12-12 22:37 ` Willy Tarreau
2004-12-12 23:30 ` Bongani Hlope
2004-12-14 7:28 ` Andi Kleen
2004-09-20 14:49 ` [patch] speed up ioctls in linux kernel Michael S. Tsirkin
[not found] <fa.fjvgjkq.i3u4a0@ifi.uio.no>
[not found] ` <fa.hdf3d0t.iik609@ifi.uio.no>
2004-12-16 13:00 ` how to detect a 32 bit process on 64 bit kernel Bodo Eggert
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