From: Florian Weimer <fweimer@redhat.com>
To: Rich Felker <dalias@libc.org>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>,
GNU C Library <libc-alpha@sourceware.org>,
nd@arm.com, Jeff Law <law@redhat.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>,
Wilco Dijkstra <Wilco.Dijkstra@arm.com>,
James Greenhalgh <James.Greenhalgh@arm.com>
Subject: Re: [RFC] nptl: change default stack guard size of threads
Date: Wed, 29 Nov 2017 21:02:00 -0000 [thread overview]
Message-ID: <00c123b5-dd46-6777-2c24-d80eae8d35df@redhat.com> (raw)
In-Reply-To: <20171129205148.GG1627@brightrain.aerifal.cx>
On 11/29/2017 09:51 PM, Rich Felker wrote:
> I'm not sure I follow, but from the standpoint of virtual address
> space and what is an acceptable cost in wasted address space, any
> ILP32-on-64 ABIs should be considered the same as 32-bit archs. As
> such, I think GCC really needs to do the stack probe every 4k, not
> 64k, and the default (and certainly minimum-supported) guard size
> should be kept at 4k, not 64k or anything larger.
Yes, and I expect that we will keep using 4 KiB probing on i386 (and
s390/s390x). That's what Jeff gave me for testing. I do hope the final
upstream version isn't going to be different in this regard.
But in the end, this is up to the machine maintainers (for gcc and glibc).
>> We can throw new code at this problem and solve it for 64-bit. For
>> 32-bit, we simply do not have a universally applicable solution. My
>> understanding was that everywhere except on ARM, GCC was compatible
>> with the pioneering glibc/Linux work in this area (the guard page we
>> added to thread stacks, and the guard page added by the kernel). If
>> this isn't the case, then I'm really disappointed in the disregard
>> of existing practice on the GCC side.
>
> Hm? What are you thinking of that GCC might have gotten wrong?
Use 64 KiB probe intervals (almost) everywhere as an optimization. I
assumed the original RFC patch was motivated by that.
I knew that ARM would be broken because that's what the gcc ARM
maintainers want. I assumed that it was restricted to that, but now I'm
worried that it's not.
Thanks,
Florian
next prev parent reply other threads:[~2017-11-29 21:02 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-29 14:59 Szabolcs Nagy
2017-11-29 15:18 ` Florian Weimer
2017-11-29 18:17 ` Carlos O'Donell
2017-11-29 18:29 ` Rich Felker
2017-11-29 20:33 ` Florian Weimer
2017-11-29 18:40 ` Szabolcs Nagy
2017-11-29 20:44 ` Florian Weimer
2017-11-29 20:52 ` Rich Felker
2017-11-29 21:02 ` Florian Weimer [this message]
2017-11-29 23:13 ` Szabolcs Nagy
2017-12-05 10:55 ` James Greenhalgh
2017-12-06 12:51 ` Florian Weimer
2017-12-11 23:49 ` Jeff Law
2017-12-12 11:43 ` Szabolcs Nagy
2017-12-12 16:36 ` Rich Felker
2017-12-12 18:07 ` Szabolcs Nagy
2017-12-12 19:30 ` Florian Weimer
2017-12-13 11:58 ` Szabolcs Nagy
2017-12-19 12:35 ` James Greenhalgh
2017-12-19 13:06 ` Florian Weimer
2017-12-19 18:21 ` Szabolcs Nagy
2017-12-19 20:34 ` Rich Felker
2017-12-20 4:42 ` Jeff Law
2017-12-20 4:49 ` Rich Felker
2017-12-27 13:08 ` Wilco Dijkstra
2017-12-20 4:45 ` Jeff Law
2017-11-29 22:28 ` Wilco Dijkstra
2017-11-29 22:38 ` Carlos O'Donell
2017-12-06 12:53 ` Florian Weimer
2017-12-06 13:10 ` Wilco Dijkstra
2017-12-06 13:13 ` Florian Weimer
2017-11-29 23:02 ` Rich Felker
2017-12-06 13:16 ` Florian Weimer
2017-12-06 13:40 ` Joseph Myers
2017-12-06 13:51 ` Florian Weimer
2017-12-06 14:44 ` Jeff Law
2017-12-06 14:27 ` Wilco Dijkstra
2017-12-06 20:41 ` Szabolcs Nagy
2017-12-06 21:24 ` Adhemerval Zanella
2017-12-06 22:08 ` Rich Felker
2017-12-08 18:28 ` Szabolcs Nagy
2017-11-29 22:45 ` Szabolcs Nagy
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=00c123b5-dd46-6777-2c24-d80eae8d35df@redhat.com \
--to=fweimer@redhat.com \
--cc=James.Greenhalgh@arm.com \
--cc=Richard.Earnshaw@arm.com \
--cc=Wilco.Dijkstra@arm.com \
--cc=dalias@libc.org \
--cc=law@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=nd@arm.com \
--cc=szabolcs.nagy@arm.com \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).