linux-kernel - Re: [PATCH] MIPS: Make 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]

Date:	Sat, 22 Nov 2008 09:39:35 +0000
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	David Daney <ddaney@...iumnetworks.com>
Cc:	linux-mips <linux-mips@...ux-mips.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Make BUG() __noreturn.

On Thu, Nov 20, 2008 at 05:26:36PM -0800, David Daney wrote:
> From: David Daney <ddaney@...iumnetworks.com>
> Date: Thu, 20 Nov 2008 17:26:36 -0800
> To: linux-mips <linux-mips@...ux-mips.org>
> CC: linux-kernel@...r.kernel.org
> Subject: [PATCH] MIPS: Make BUG() __noreturn.
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> MIPS: Make BUG() __noreturn.

Please don't repeat the subject in the body of a patch email.  Git takes
the subject followed by the body upto the --- line as the log message so
this is just duplication that will need to be manually deleted again.

> Often we do things like put BUG() in the default clause of a case
> statement.  Since it was not declared __noreturn, this could sometimes
> lead to bogus compiler warnings that variables were used
> uninitialized.
>
> There is a small problem in that we have to put a magic while(1); loop to
> fool GCC into really thinking it is noreturn.  This makes the new
> BUG() function 3 instructions long instead of just 1, but I think it
> is worth it as it is now unnecessary to do extra work to silence the
> 'used uninitialized' warnings.
>
> I also re-wrote BUG_ON so that if it is given a constant condition, it
> just does BUG() instead of loading a constant value in to a register
> and testing it.

I don't like the endless loop in the BUG() macros but at this time it seems
the best solution.  Looking forward to __builtin_noreturn().

Patch applied,

  Ralf
--
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/