Message-ID: <1379824861.24090.12.camel@pasglop>
Subject: Re: [RFC GIT PULL] softirq: Consolidation and stack overrun fix
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: 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>,
        Peter Zijlstra <peterz@infradead.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>
Date: Sun, 22 Sep 2013 14:41:01 +1000
In-Reply-To: <1379824754.24090.11.camel@pasglop>
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On Sun, 2013-09-22 at 14:39 +1000, Benjamin Herrenschmidt wrote:
> How do you do your per-cpu on x86 ? On powerpc we struggle because we
> try to dedicate a register (r13) to this PACA (the per-cpu offset hangs
> off it), but we constantly run into issues where gcc copies r13 to
> another register and then indexes off that, even accross
> preempt_enable/disable sections, or worst such as saving/restoring from
> the stack. We can't seem to get the compiler to treat it appropriately
> as volatile.

Also, do you have a half-decent way of getting to per-cpu from asm ?

Cheers,
Ben.


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