linux-kernel - Re: jump_label defaults (was Re: [patch 00/17] CFS Bandwidth Control v7.1)

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: <1310116832.3282.699.camel@twins>
Date:	Fri, 08 Jul 2011 11:20:32 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Jason Baron <jbaron@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>,
	linux-kernel@...r.kernel.org,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	Dhaval Giani <dhaval.giani@...il.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Hu Tao <hutao@...fujitsu.com>, Mike Galbraith <efault@....de>
Subject: Re: jump_label defaults (was Re: [patch 00/17] CFS Bandwidth
 Control v7.1)

On Thu, 2011-07-07 at 22:36 +0200, Peter Zijlstra wrote:
> Hrm,. I can't seem to make that work, damn CPP for not being
> recursive.

Ha! the wonders of sleep, ok I can make this part work.

So how do we write this static_branch_true() thing?

But then I realized that if we do something like:

static __always_inline bool arch_static_branch(struct jump_label_key *key)
{
        asm goto("1:"
                JUMP_LABEL_INITIAL_NOP
                ".pushsection __jump_table,  \"aw\" \n\t"
                _ASM_ALIGN "\n\t"
                _ASM_PTR "1b, %l[l_yes], %c0 \n\t"
                ".popsection \n\t"
                : :  "i" (key) : : l_yes);
        return false;
l_yes:
        return true;
}

Simply flipping the true and false in there isn't going to work, because
then its similar to !static_branch() and jump_label_inc() is going to
disable it.
--
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/