linux-kernel - Re: [tip:perf/uprobes] uprobes/core: Clean up, refactor and improve the code

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:	Mon, 20 Feb 2012 15:43:37 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	jkenisto@...ibm.com, a.p.zijlstra@...llo.nl, ananth@...ibm.com,
	anton@...hat.com, masami.hiramatsu.pt@...achi.com,
	acme@...radead.org, oleg@...hat.com, tglx@...utronix.de,
	Benjamin Herrenschmidt <benh@....ibm.com>,
	Josh Stone <jistone@...hat.com>,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/uprobes] uprobes/core: Clean up,  refactor and
 improve the code

* Ingo Molnar <mingo@...e.hu> [2012-02-20 08:38:23]:

> 
> * Srikar Dronamraju <srikar@...ux.vnet.ibm.com> wrote:
> 
> > The volatiles were added to arch/x86/kernel/kprobes.c because 
> > of commit 7115e3fcf45 and 315eb8a2a1b. The volatiles are 
> > required because gcc 4.6 gave a warning about the asm operand 
> > for test_bit.  So the same were added to 
> > arch/x86/kernel/uprobes.c.
> 
> Seems like a GCC bug - a bogus warning - or does it generate bad 
> code as well?

Yes it is a gcc bug and was fixed by Jakub.
As per Josh, only the first long is output if compiled on the buggy gcc.

> 
> In any case, kprobes.c did it correctly, it added the volatile 
> *and a comment*, pointing out that it's a GCC bug. No such 
> warning was added to uprobes.c, making the volatile look 
> entirely spurious.

okay. 

> 
> So feel free to re-add the volatile in a followup patch, just 
> make sure the GCC workaround nature is documented.
> 
> Thanks,
> 
> 	Ingo
> 

--
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/