linux-kernel - Re: [PATCH][RFC] getting rid of stupid loop in BUG()

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]

Message-ID: <46A786C7.9020604@zytor.com>
Date:	Wed, 25 Jul 2007 10:22:15 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Al Viro <viro@....linux.org.uk>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Miller <davem@...emloft.net>, jeremy@...p.org,
	kaos@....com.au, xyzzy@...akeasy.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH][RFC] getting rid of stupid loop in BUG()

Al Viro wrote:
> On Wed, Jul 25, 2007 at 09:56:12AM -0700, Linus Torvalds wrote:
>>
>> On Tue, 24 Jul 2007, David Miller wrote:
>>> From: Jeremy Fitzhardinge <jeremy@...p.org>
>>> Date: Tue, 24 Jul 2007 23:24:55 -0700
>>>
>>>> H. Peter Anvin wrote:
>>>>> How far back was __builtin_trap() supported?
>>>> I think its relatively recent, but it might be within our supported
>>>> compiler window.
>>> I'm pretty sure it is.
>> .. and I'm pretty sure it's immaterial.
>>
>> We don't just do the "ud2" instruction - we also do the file and line 
>> number information after it. Which means that __builtin_trap() is useless.
>>
>> So we might as well keep the loop, since both are two-byte instructions 
>> that tell gcc that it will never continue.
> 
> Umm...  Actually, we might be able to do something like
> {
> 	l: __builtin_trap();
> 	static struct ... v __attribute__((section(...))) = { &&l, n, file };
> }
> 
> except that it would need block-local labels and those are ugly (so's
> &&<label>, while we are at it)...

I thought gcc was buggy when it came to passing &&labels to assembly.

	-hpa
-
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/