From: Arnd Bergmann <arnd@arndb.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Pedro Alves <pedro@codesourcery.com>, Avi Kivity <avi@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
"H.J. Lu" <hjl.tools@gmail.com>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Richard Kuo <rkuo@codeaurora.org>,
Mark Salter <msalter@redhat.com>, Jonas Bonn <jonas@southpole.se>,
Tobias Klauser <tklauser@distanz.ch>
Subject: Re: RFD: x32 ABI system call numbers
Date: Fri, 02 Sep 2011 10:02:38 +0200 [thread overview]
Message-ID: <3265903.Gp9iD1LkVC@wuerfel> (raw)
In-Reply-To: <4E6036A7.6090200@zytor.com>
On Thursday 01 September 2011 18:51:35 H. Peter Anvin wrote:
> On 09/01/2011 05:49 PM, Pedro Alves wrote:
> >>>
> >>> struct iovec
> >>> {
> >>> void __user *iov_base; /* BSD uses caddr_t (1003.1g requires
> >>> void *) */
> >>> __kernel_size_t iov_len; /* Must be size_t (1003.1g) */
> >>> } __attribute__((x32_abi_64));
> >>>
> >>> typedef long time_t __attribute__((x32_abi_64));
> >>>
> >>> The x32_abi_64 attribute converts pointers and longs back to 64-bit and
> >>> adjusts the alignment accordingly. If we tag all userspace visible
> >>> structures with this attribute, we can use the 64-bit ABI without changes.
> >
> > I would expect no new gcc extension to be needed for that -- there's the
> > mode attribute (you can read DI as 64-bit):
> >
> > typedef void * __kernel_ptr64 __attribute ((mode(DI)));
> >
> > struct iovec
> > {
> > __kernel_ptr64 iov_base;
> > ...
> > };
> >
>
> Does that work for *writing*, too? That might be a very useful little
> escape hatch for some particularly tight corners.
I've tried to use that extension in other contexts without much success,
mostly I believe because gcc back-end support for it needs to be there
but wasn't at the time I tried. If the x32 back-end does this correctly,
you win.
A different gcc extension that might turn out to be useful here is the
named address space extension that lets you annotate a pointer to
be different from other pointers. On the SPU architecture we use this
for the destinction between local 18 bit pointers and 64-bit pointers
into the user process address space.
Arnd
next prev parent reply other threads:[~2011-09-02 8:05 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-26 23:00 RFD: x32 ABI system call numbers H. Peter Anvin
2011-08-26 23:13 ` Linus Torvalds
2011-08-26 23:39 ` H. Peter Anvin
2011-08-27 0:36 ` Linus Torvalds
2011-08-27 0:43 ` Linus Torvalds
2011-08-27 0:53 ` H. Peter Anvin
2011-08-27 1:18 ` Linus Torvalds
2011-08-27 1:35 ` H. Peter Anvin
2011-08-27 1:45 ` Linus Torvalds
2011-08-27 1:12 ` H. Peter Anvin
2011-08-27 1:42 ` Linus Torvalds
2011-08-29 19:01 ` Geert Uytterhoeven
2011-08-29 19:03 ` H. Peter Anvin
2011-08-30 1:17 ` Ted Ts'o
2011-08-30 1:48 ` Linus Torvalds
2011-08-30 2:16 ` Kyle Moffett
2011-08-30 4:45 ` H. Peter Anvin
2011-08-30 7:06 ` Geert Uytterhoeven
2011-08-30 12:18 ` Arnd Bergmann
2011-08-30 7:09 ` Andi Kleen
2011-08-30 9:56 ` Alan Cox
2011-08-30 7:00 ` Geert Uytterhoeven
2011-09-20 18:37 ` Jan Engelhardt
2011-09-06 20:40 ` Florian Weimer
2011-08-27 0:57 ` H. Peter Anvin
2011-08-27 4:40 ` Christoph Hellwig
2011-08-29 15:04 ` Arnd Bergmann
2011-08-29 18:31 ` H. Peter Anvin
2011-08-30 12:09 ` Arnd Bergmann
2011-08-30 16:35 ` H. Peter Anvin
2011-08-31 16:14 ` Arnd Bergmann
2011-08-31 16:25 ` H. Peter Anvin
2011-08-31 16:39 ` Arnd Bergmann
2011-08-31 16:48 ` Linus Torvalds
2011-08-31 19:18 ` Arnd Bergmann
2011-08-31 19:44 ` H. Peter Anvin
2011-08-31 19:54 ` Alan Cox
2011-08-31 20:02 ` H. Peter Anvin
2011-08-31 20:55 ` Arnd Bergmann
2011-08-31 20:58 ` H. Peter Anvin
2011-08-31 19:49 ` Geert Uytterhoeven
2011-08-31 16:46 ` Linus Torvalds
2011-08-31 17:05 ` H.J. Lu
2011-09-03 2:56 ` H.J. Lu
2011-09-03 3:04 ` Linus Torvalds
2011-09-03 4:02 ` H.J. Lu
2011-09-03 4:29 ` H. Peter Anvin
2011-09-03 4:44 ` H.J. Lu
2011-09-03 5:16 ` H. Peter Anvin
2011-09-03 14:11 ` H.J. Lu
2011-09-03 5:29 ` H. Peter Anvin
2011-09-03 8:41 ` Arnd Bergmann
2011-09-03 14:04 ` Valdis.Kletnieks
2011-09-03 16:40 ` H. Peter Anvin
2011-09-03 17:16 ` Valdis.Kletnieks
2011-09-03 17:22 ` H.J. Lu
2011-09-03 17:28 ` H. Peter Anvin
2011-09-03 17:27 ` H. Peter Anvin
2011-09-04 13:51 ` Valdis.Kletnieks
2011-09-04 15:17 ` Arnd Bergmann
2011-09-04 17:08 ` Linus Torvalds
2011-09-04 18:40 ` H.J. Lu
2011-09-04 19:06 ` Arnd Bergmann
2011-09-04 19:31 ` H.J. Lu
2011-09-04 21:13 ` Arnd Bergmann
2011-09-04 21:25 ` H.J. Lu
2011-09-04 21:41 ` Arnd Bergmann
2011-09-04 22:13 ` H.J. Lu
2011-09-05 7:48 ` Arnd Bergmann
2011-09-05 15:11 ` H.J. Lu
2011-09-05 17:21 ` Arnd Bergmann
2011-09-05 19:34 ` H.J. Lu
2011-09-05 19:54 ` H.J. Lu
2011-09-05 19:59 ` H. Peter Anvin
2011-09-05 20:27 ` Arnd Bergmann
2011-09-09 21:02 ` H.J. Lu
2011-09-04 20:11 ` H. Peter Anvin
2011-09-04 19:31 ` richard -rw- weinberger
2011-09-04 19:32 ` H.J. Lu
2011-09-03 14:15 ` H.J. Lu
2011-08-31 17:09 ` H. Peter Anvin
2011-08-31 17:19 ` Linus Torvalds
2011-08-31 17:38 ` H. Peter Anvin
2011-09-01 11:35 ` Arnd Bergmann
2011-10-01 19:38 ` Jonas Bonn
2012-02-08 21:36 ` 64-bit time on 32-bit systems H. Peter Anvin
2011-09-01 13:30 ` RFD: x32 ABI system call numbers Avi Kivity
2011-09-01 14:13 ` H. Peter Anvin
2011-09-02 0:49 ` Pedro Alves
2011-09-02 1:51 ` H. Peter Anvin
2011-09-02 8:02 ` Arnd Bergmann [this message]
2011-09-02 8:42 ` Pedro Alves
2011-09-01 6:08 ` Jonas Bonn
2011-09-02 6:17 ` Andy Lutomirski
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=3265903.Gp9iD1LkVC@wuerfel \
--to=arnd@arndb.de \
--cc=avi@redhat.com \
--cc=hch@infradead.org \
--cc=hjl.tools@gmail.com \
--cc=hpa@zytor.com \
--cc=jonas@southpole.se \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=msalter@redhat.com \
--cc=pedro@codesourcery.com \
--cc=rkuo@codeaurora.org \
--cc=tglx@linutronix.de \
--cc=tklauser@distanz.ch \
--cc=torvalds@linux-foundation.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).