From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v2 1/3] ARM: catch pending imprecise abort on unmask Date: Thu, 15 Oct 2015 09:23:07 -0700 Message-ID: <20151015162307.GP10113@atomide.com> References: <1444905142-21500-1-git-send-email-l.stach@pengutronix.de> <1444905142-21500-2-git-send-email-l.stach@pengutronix.de> <20151015153246.GH32536@n2100.arm.linux.org.uk> <20151015153915.GO10113@atomide.com> <20151015160631.GI32536@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20151015160631.GI32536@n2100.arm.linux.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Russell King - ARM Linux Cc: Hauke Mehrtens , linux-omap@vger.kernel.org, patchwork-lst@pengutronix.de, linux-arm-kernel@lists.infradead.org, Lucas Stach List-Id: linux-omap@vger.kernel.org * Russell King - ARM Linux [151015 09:11]: > On Thu, Oct 15, 2015 at 08:39:15AM -0700, Tony Lindgren wrote: > > * Russell King - ARM Linux [151015 08:37]: > > > On Thu, Oct 15, 2015 at 12:32:20PM +0200, Lucas Stach wrote: > > > > Install a non-faulting handler just before unmasking imprecise aborts > > > > and switch back to the regular one after unmasking is done. > > > > > > > > This catches any pending imprecise abort that the firmware/bootloader > > > > may have left behind that would normally crash the kernel at that point. > > > > As there are apparently a lot of bootlaoders out there that do such a > > > > thing it makes sense to handle it in the common startup code. > > > > > > > > Signed-off-by: Lucas Stach > > > > > > Much better. Please feel free to add it to the patch system, thanks. > > > > > > I think, given that the original seems to be breaking platforms, this > > > patch needs to go into -rc kernels, right? > > > > Hmm do we still see a trace where the issue happened though with this > > one? > > That's not the intention of this specific patch. > > This is solely to detect the bootloader induced imprecise exception, > nothing more. A backtrace for that won't be useful in any shape or > form - in fact, the backtrace will be well known (it'll be from the > site where the imprecise exceptions are unmasked.) > > Any imprecise exception which happens after this will be handled in > the normal way: it'll raise a kernel oops, and that will have all the > details that a kernel oops normally has. OK makes sense. > The difference is, rather than the boot loader provoking the kernel to > oops at this point, we're able to report the event and continue on. OK Tony From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Thu, 15 Oct 2015 09:23:07 -0700 Subject: [PATCH v2 1/3] ARM: catch pending imprecise abort on unmask In-Reply-To: <20151015160631.GI32536@n2100.arm.linux.org.uk> References: <1444905142-21500-1-git-send-email-l.stach@pengutronix.de> <1444905142-21500-2-git-send-email-l.stach@pengutronix.de> <20151015153246.GH32536@n2100.arm.linux.org.uk> <20151015153915.GO10113@atomide.com> <20151015160631.GI32536@n2100.arm.linux.org.uk> Message-ID: <20151015162307.GP10113@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Russell King - ARM Linux [151015 09:11]: > On Thu, Oct 15, 2015 at 08:39:15AM -0700, Tony Lindgren wrote: > > * Russell King - ARM Linux [151015 08:37]: > > > On Thu, Oct 15, 2015 at 12:32:20PM +0200, Lucas Stach wrote: > > > > Install a non-faulting handler just before unmasking imprecise aborts > > > > and switch back to the regular one after unmasking is done. > > > > > > > > This catches any pending imprecise abort that the firmware/bootloader > > > > may have left behind that would normally crash the kernel at that point. > > > > As there are apparently a lot of bootlaoders out there that do such a > > > > thing it makes sense to handle it in the common startup code. > > > > > > > > Signed-off-by: Lucas Stach > > > > > > Much better. Please feel free to add it to the patch system, thanks. > > > > > > I think, given that the original seems to be breaking platforms, this > > > patch needs to go into -rc kernels, right? > > > > Hmm do we still see a trace where the issue happened though with this > > one? > > That's not the intention of this specific patch. > > This is solely to detect the bootloader induced imprecise exception, > nothing more. A backtrace for that won't be useful in any shape or > form - in fact, the backtrace will be well known (it'll be from the > site where the imprecise exceptions are unmasked.) > > Any imprecise exception which happens after this will be handled in > the normal way: it'll raise a kernel oops, and that will have all the > details that a kernel oops normally has. OK makes sense. > The difference is, rather than the boot loader provoking the kernel to > oops at this point, we're able to report the event and continue on. OK Tony