linux-kernel - Re: Kernel broken on processors without performance counters

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: <CALCETrXvgxdQTAgxsnR5kGk=orHQ0PZWDjhM-qhQSYY+EssUSg@mail.gmail.com>
Date:	Thu, 23 Jul 2015 10:35:36 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"hillf. zj" <hillf.zj@...baba-inc.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Jason Baron <jasonbaron0@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Kees Cook <keescook@...omium.org>,
	Vince Weaver <vince@...ter.net>,
	Borislav Petkov <bp@...en8.de>,
	Valdis Kletnieks <Valdis.Kletnieks@...edu>,
	Steven Rostedt <rostedt@...dmis.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>
Subject: Re: Kernel broken on processors without performance counters

On Jul 23, 2015 10:08 AM, "Peter Zijlstra" <peterz@...radead.org> wrote:
>
> On Thu, Jul 23, 2015 at 11:34:50AM -0400, Steven Rostedt wrote:
> > On Thu, 23 Jul 2015 12:42:15 +0200
> > Peter Zijlstra <peterz@...radead.org> wrote:
> >
> > > static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
> > > {
> > >     if (!inv) {
> > >             asm_volatile_goto("1:"
> > >                     "jmp %l[l_yes]\n\t"
> >
> > And what happens when this gets converted to a two byte jump?
> >
>
> That would be bad, how can we force it to emit 5 bytes?

jmp.d32 on newer toolchains IIRC.

--Andy
--
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/