From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@au1.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
James Hogan <james.hogan@imgtec.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"David S. Miller" <davem@davemloft.net>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC GIT PULL] softirq: Consolidation and stack overrun fix
Date: Mon, 23 Sep 2013 08:00:06 +1000 [thread overview]
Message-ID: <1379887206.24090.22.camel@pasglop> (raw)
In-Reply-To: <523F2D21.5070505@zytor.com>
On Sun, 2013-09-22 at 10:47 -0700, H. Peter Anvin wrote:
> On 09/22/2013 09:24 AM, Peter Zijlstra wrote:
> >
> > As to the problem of GCC moving r13 about, some archs have some
> > exceptions in the register allocator and leave some registers alone.
> > IIRC MIPS has this and uses one of those (istr there's 2) for the
> > per cpu base address.
> >
>
> You can force gcc to leave a register alone with the command line option
> -ffixed-r13.
Haven't tried that in a while but iirc, from the discussions I had with
the gcc folks, it didn't work the way we wanted.
Basically, it still assumes that it's not going to change at random
points, I can't have something like
register volatile unsigned long pre_cpu_offset asm("r13")
It will barf on the "volatile" and if I don't have it, it will make
assumptions that r13 doesn't change, and thus might copy its value
in another cpu accross preempt_enable/disable.
I think I need another sessions with gcc folks on that one.
Cheers,
Ben.
next prev parent reply other threads:[~2013-09-22 22:01 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-19 19:51 [RFC GIT PULL] softirq: Consolidation and stack overrun fix Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 1/3] irq: Consolidate do_softirq() arch overriden implementations Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 2/3] irq: Execute softirq on its own stack on irq exit Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 3/3] irq: Comment on the use of inline stack for ksoftirqd Frederic Weisbecker
2013-09-20 0:02 ` [RFC GIT PULL] softirq: Consolidation and stack overrun fix Linus Torvalds
2013-09-20 1:53 ` Benjamin Herrenschmidt
2013-09-20 11:03 ` Thomas Gleixner
2013-09-20 11:11 ` Peter Zijlstra
2013-09-21 0:55 ` Benjamin Herrenschmidt
2013-09-20 16:26 ` Frederic Weisbecker
2013-09-20 17:30 ` Thomas Gleixner
2013-09-20 18:37 ` Frederic Weisbecker
2013-09-20 22:14 ` Linus Torvalds
2013-09-21 7:47 ` Ingo Molnar
2013-09-21 18:58 ` Frederic Weisbecker
2013-09-21 21:45 ` Benjamin Herrenschmidt
2013-09-21 23:27 ` Frederic Weisbecker
2013-09-22 2:01 ` H. Peter Anvin
2013-09-22 4:39 ` Benjamin Herrenschmidt
2013-09-22 4:41 ` Benjamin Herrenschmidt
2013-09-22 16:24 ` Peter Zijlstra
2013-09-22 17:47 ` H. Peter Anvin
2013-09-22 22:00 ` Benjamin Herrenschmidt [this message]
2013-09-22 21:56 ` Benjamin Herrenschmidt
2013-09-22 22:22 ` Linus Torvalds
2013-09-22 22:38 ` Benjamin Herrenschmidt
2013-09-23 4:35 ` [PATCH] powerpc/irq: Run softirqs off the top of the irq stack Benjamin Herrenschmidt
2013-09-23 7:56 ` Stephen Rothwell
2013-09-23 10:13 ` Benjamin Herrenschmidt
2013-09-23 16:47 ` Linus Torvalds
2013-09-23 20:51 ` Benjamin Herrenschmidt
2013-09-24 5:42 ` [PATCH v2] " Benjamin Herrenschmidt
2013-09-23 17:59 ` [RFC GIT PULL] softirq: Consolidation and stack overrun fix Chris Metcalf
2013-09-23 20:57 ` Benjamin Herrenschmidt
2013-09-24 19:27 ` Chris Metcalf
2013-09-24 20:58 ` Benjamin Herrenschmidt
2013-09-24 0:10 ` Benjamin Herrenschmidt
2013-09-24 1:19 ` Linus Torvalds
2013-09-24 1:52 ` Benjamin Herrenschmidt
2013-09-24 8:04 ` Peter Zijlstra
2013-09-24 8:16 ` Benjamin Herrenschmidt
2013-09-24 8:21 ` Peter Zijlstra
2013-09-24 9:31 ` Benjamin Herrenschmidt
2013-09-23 4:40 ` Benjamin Herrenschmidt
2013-09-23 5:01 ` David Miller
2013-09-24 2:44 ` Frederic Weisbecker
2013-09-24 4:42 ` Benjamin Herrenschmidt
2013-09-24 13:56 ` Frederic Weisbecker
2013-09-24 20:55 ` Benjamin Herrenschmidt
2013-09-25 8:46 ` Frederic Weisbecker
2013-09-21 0:52 ` Benjamin Herrenschmidt
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