Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754123Ab2BDSBH (ORCPT ); Sat, 4 Feb 2012 13:01:07 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:52641 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753914Ab2BDSBF (ORCPT ); Sat, 4 Feb 2012 13:01:05 -0500 Date: Sat, 4 Feb 2012 18:00:16 +0000 From: Catalin Marinas To: Stephen Boyd Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Nicolas Pitre Subject: Re: [PATCH] ARM: cache-v7: Disable preemption when reading CCSIDR Message-ID: <20120204180016.GB30910@arm.com> References: <1328234629-32735-1-git-send-email-sboyd@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1328234629-32735-1-git-send-email-sboyd@codeaurora.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1606 Lines: 35 On Fri, Feb 03, 2012 at 02:03:49AM +0000, Stephen Boyd wrote: > armv7's flush_cache_all() flushes caches via set/way. To > determine the cache attributes (line size, number of sets, > etc.) the assembly first writes the CSSELR register to select a > cache level and then reads the CCSIDR register. The CSSELR register > is banked per-cpu and is used to determine which cache level CCSIDR > reads. If the task is migrated between when the CSSELR is written and > the CCSIDR is read the CCSIDR value may be for an unexpected cache > level (for example L1 instead of L2) and incorrect cache flushing > could occur. > > Disable interrupts across the write and read so that the correct > cache attributes are read and used for the cache flushing > routine. We disable interrupts instead of disabling preemption > because the critical section is only 3 instructions and we want > to call v7_dcache_flush_all from __v7_setup which doesn't have a > full kernel stack with a struct thread_info. > > This fixes a problem we see in scm_call() when flush_cache_all() > is called from preemptible context and sometimes the L2 cache is > not properly flushed out. > > Signed-off-by: Stephen Boyd > Cc: Catalin Marinas > Cc: Nicolas Pitre Acked-by: Catalin Marinas -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/