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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=41BE0A75.3070206@didntduck.org \
--to=bgerst@didntduck.org \
--cc=ak@suse.de \
--cc=discuss@x86-64.org \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@mellanox.co.il \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.