linux-kernel - Re: [PATCH 13/14] x86/ticketlock: add slowpath logic

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:	Wed, 17 Nov 2010 00:52:24 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Jan Beulich <JBeulich@...ell.com>
CC:	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	Eric Dumazet <dada1@...mosbay.com>, xiyou.wangcong@...il.com,
	Peter Zijlstra <peterz@...radead.org>,
	Nick Piggin <npiggin@...nel.dk>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Linux Virtualization <virtualization@...ts.linux-foundation.org>,
	Xen-devel <xen-devel@...ts.xensource.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	Avi Kivity <avi@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 13/14] x86/ticketlock: add slowpath logic

On 11/17/2010 12:31 AM, Jan Beulich wrote:
>>>> On 16.11.10 at 22:08, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
>> +static inline void __ticket_enter_slowpath(struct arch_spinlock *lock)
>> +{
>> +	if (sizeof(lock->tickets.tail) == sizeof(u8))
>> +		asm (LOCK_PREFIX "orb %1, %0"
>> +		     : "+m" (lock->tickets.tail)
>> +		     : "i" (TICKET_SLOWPATH_FLAG) : "memory");
>> +	else
>> +		asm (LOCK_PREFIX "orw %1, %0"
>> +		     : "+m" (lock->tickets.tail)
>> +		     : "i" (TICKET_SLOWPATH_FLAG) : "memory");
>> +}
> Came only now to mind: Here and elsewhere, did you try using
> %z0 to have gcc produce the opcode suffix character, rather
> than having these somewhat ugly if()-s?

Actually in this case I'm pretty sure there's already a "set bit"
function which will do the job.  set_bit(), I guess, though it takes a
bit number rather than a mask...

But, yes, %z0 sounds interesting.  Is it documented anywhere?  I think
I've tried to use it in the past and run into gcc bugs.

Thanks,
    J
--
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/