From: Peter Zijlstra <peterz@infradead.org>
To: Florian Weimer <fweimer@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Russell King <linux@arm.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
linux-api <linux-api@vger.kernel.org>,
Paul Turner <pjt@google.com>, Andrew Hunter <ahh@google.com>,
Andy Lutomirski <luto@amacapital.net>,
Andi Kleen <andi@firstfloor.org>,
Dave Watson <davejwatson@fb.com>, Chris Lameter <cl@linux.com>,
Ben Maurer <bmaurer@fb.com>, rostedt <rostedt@goodmis.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Josh Triplett <josh@joshtriplett.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Boqun Feng <boqun.feng@gmail.com>
Subject: Re: [RFC PATCH v6 1/5] Thread-local ABI system call: cache CPU number of running thread
Date: Thu, 7 Apr 2016 13:19:38 +0200 [thread overview]
Message-ID: <20160407111938.GR3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <570638D9.7010108@redhat.com>
On Thu, Apr 07, 2016 at 12:39:21PM +0200, Florian Weimer wrote:
> On 04/07/2016 12:31 PM, Peter Zijlstra wrote:
> > On Thu, Apr 07, 2016 at 11:01:25AM +0200, Florian Weimer wrote:
> >>> Because ideally this structure would be part of the initial (glibc) TCB
> >>> with fixed offset etc.
> >>
> >> This is not possible because we have layering violations and code
> >> assumes it knows the precise of the glibc TCB. I think Address
> >> Sanitizer is in this category. This means we cannot adjust the TCB size
> >> based on the kernel headers used to compile glibc, and there will have
> >> to be some indirection.
> >
> > So with the proposed fixed sized object it would work, right?
>
> I didn't see a proposal for a fixed size buffer, in the sense that the
> size of struct sockaddr_in is fixed.
This thing proposed a single 64byte structure (with the possibility of
eventually adding more 64byte structures). Basically:
struct tlabi {
union {
__u8[64] __foo;
struct {
/* fields go here */
};
};
} __aligned__(64);
People objected against the fixed size scheme, but it being possible to
get a fixed TCB offset and reduce indirections is a big win IMO.
next prev parent reply other threads:[~2016-04-07 11:20 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 17:01 [RFC PATCH v6 0/5] Thread-local ABI system call (CPU number cache) Mathieu Desnoyers
2016-04-04 17:01 ` [RFC PATCH v6 1/5] Thread-local ABI system call: cache CPU number of running thread Mathieu Desnoyers
2016-04-04 17:11 ` H. Peter Anvin
2016-04-04 19:46 ` Mathieu Desnoyers
2016-04-04 20:48 ` Mathieu Desnoyers
2016-04-05 16:02 ` Florian Weimer
2016-04-05 16:47 ` Peter Zijlstra
2016-04-07 9:01 ` Florian Weimer
2016-04-07 10:31 ` Peter Zijlstra
2016-04-07 10:39 ` Florian Weimer
2016-04-07 11:19 ` Peter Zijlstra [this message]
2016-04-07 12:03 ` Florian Weimer
2016-04-07 12:25 ` Peter Zijlstra
2016-04-07 12:37 ` Florian Weimer
2016-04-07 15:59 ` Mathieu Desnoyers
2016-04-07 12:34 ` Mathieu Desnoyers
2016-04-07 16:39 ` Linus Torvalds
2016-04-07 16:46 ` Andy Lutomirski
2016-04-07 16:50 ` Florian Weimer
2016-04-07 16:59 ` Linus Torvalds
2016-04-07 16:52 ` Linus Torvalds
2016-04-07 18:43 ` Mathieu Desnoyers
2016-04-07 20:22 ` Andi Kleen
2016-04-07 20:55 ` Mathieu Desnoyers
2016-04-07 10:40 ` Florian Weimer
2016-04-04 17:01 ` [RFC PATCH v6 2/5] Thread-local ABI cpu_id: ARM resume notifier Mathieu Desnoyers
2016-04-04 17:01 ` [RFC PATCH v6 3/5] Thread-local ABI: wire up ARM system call Mathieu Desnoyers
2016-04-04 17:01 ` [RFC PATCH v6 4/5] Thread-local ABI cpu_id: x86 32/64 resume notifier Mathieu Desnoyers
2016-04-04 17:01 ` [RFC PATCH v6 5/5] Thread-local ABI: wire up x86 32/64 system call Mathieu Desnoyers
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