From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754691AbdEQOYH (ORCPT ); Wed, 17 May 2017 10:24:07 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:29714 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754505AbdEQOYC (ORCPT ); Wed, 17 May 2017 10:24:02 -0400 Subject: Re: [PATCH v2] misc: sram-exec: Use aligned fncpy instead of memcpy To: Tony Lindgren , Russell King - ARM Linux References: <20170410145247.6023-1-d-gerlach@ti.com> <20170503185533.GS23750@n2100.armlinux.org.uk> <20170516160127.GH31418@atomide.com> <20170517091317.GA17902@kroah.com> <20170517114307.GU23750@n2100.armlinux.org.uk> <20170517134734.GA10818@atomide.com> CC: Greg Kroah-Hartman , Arnd Bergmann , , , , Shawn Guo , Alexandre Belloni , Keerthy J From: Dave Gerlach Message-ID: Date: Wed, 17 May 2017 09:23:17 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20170517134734.GA10818@atomide.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [128.247.59.203] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/17/2017 08:47 AM, Tony Lindgren wrote: > * Russell King - ARM Linux [170517 04:46]: >> On Wed, May 17, 2017 at 11:13:17AM +0200, Greg Kroah-Hartman wrote: >>> On Tue, May 16, 2017 at 09:01:27AM -0700, Tony Lindgren wrote: >>>> * Russell King - ARM Linux [170503 11:58]: >>>>> On Mon, Apr 10, 2017 at 09:52:47AM -0500, Dave Gerlach wrote: >>>>>> Currently the sram-exec functionality, which allows allocation of >>>>>> executable memory and provides an API to move code to it, is only >>>>>> selected in configs for the ARM architecture. Based on commit >>>>>> 5756e9dd0de6 ("ARM: 6640/1: Thumb-2: Symbol manipulation macros for >>>>>> function body copying") simply copying a C function pointer address >>>>>> using memcpy without consideration of alignment and Thumb is unsafe on >>>>>> ARM platforms. >>>>>> >>>>>> The aforementioned patch introduces the fncpy macro which is a safe way >>>>>> to copy executable code on ARM platforms, so let's make use of that here >>>>>> rather than the unsafe plain memcpy that was previously used by >>>>>> sram_exec_copy. Now sram_exec_copy will move the code to "dst" and >>>>>> return an address that is guaranteed to be safely callable. >>>>>> >>>>>> In the future, architectures hoping to make use of the sram-exec >>>>>> functionality must define an fncpy macro just as ARM has done to >>>>>> guarantee or check for safe copying to executable memory before allowing >>>>>> the arch to select CONFIG_SRAM_EXEC. >>>>>> >>>>>> Signed-off-by: Dave Gerlach >>>>> >>>>> Looks a lot saner, thanks. It's just a bit sad that we lose the type >>>>> checking. >>>>> >>>>> Acked-by: Russell King >>>> >>>> Looks like this is still pending so I'll add it into >>>> omap-for-v4.12/fixes so we can get this out of the way. >>> >>> It's a "fix"? Looked to be a 4.13 issue, sorry for the delay, otherwise >>> I would have queued it up earlier. >> >> Technically, it is a fix, but my greps for "sram_exec_copy" indicate >> that the code does not yet have any in-tree users. So I don't think >> there's any urgency to picking this up, and I think no need to back >> port to stable trees. > > OK fine, I'll drop it today from my fixes (and for-next) no problem. > I did add a fixes tag to it which would then create confusion later > on too with stable trees. > > Dave, probably best to resend the patch to Greg in few days with acks > added and rebased against v4.12-rc1 because it won't apply without a > merge because of the header changes. Yes, there are no users yet. Was planning on resending this anyway, so I'll do that before I send my patches that make use of this. Regards, Dave > > Regards, > > Tony > > > > > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Gerlach Subject: Re: [PATCH v2] misc: sram-exec: Use aligned fncpy instead of memcpy Date: Wed, 17 May 2017 09:23:17 -0500 Message-ID: References: <20170410145247.6023-1-d-gerlach@ti.com> <20170503185533.GS23750@n2100.armlinux.org.uk> <20170516160127.GH31418@atomide.com> <20170517091317.GA17902@kroah.com> <20170517114307.GU23750@n2100.armlinux.org.uk> <20170517134734.GA10818@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170517134734.GA10818@atomide.com> Sender: linux-kernel-owner@vger.kernel.org To: Tony Lindgren , Russell King - ARM Linux Cc: Greg Kroah-Hartman , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Shawn Guo , Alexandre Belloni , Keerthy J List-Id: linux-omap@vger.kernel.org On 05/17/2017 08:47 AM, Tony Lindgren wrote: > * Russell King - ARM Linux [170517 04:46]: >> On Wed, May 17, 2017 at 11:13:17AM +0200, Greg Kroah-Hartman wrote: >>> On Tue, May 16, 2017 at 09:01:27AM -0700, Tony Lindgren wrote: >>>> * Russell King - ARM Linux [170503 11:58]: >>>>> On Mon, Apr 10, 2017 at 09:52:47AM -0500, Dave Gerlach wrote: >>>>>> Currently the sram-exec functionality, which allows allocation of >>>>>> executable memory and provides an API to move code to it, is only >>>>>> selected in configs for the ARM architecture. Based on commit >>>>>> 5756e9dd0de6 ("ARM: 6640/1: Thumb-2: Symbol manipulation macros for >>>>>> function body copying") simply copying a C function pointer address >>>>>> using memcpy without consideration of alignment and Thumb is unsafe on >>>>>> ARM platforms. >>>>>> >>>>>> The aforementioned patch introduces the fncpy macro which is a safe way >>>>>> to copy executable code on ARM platforms, so let's make use of that here >>>>>> rather than the unsafe plain memcpy that was previously used by >>>>>> sram_exec_copy. Now sram_exec_copy will move the code to "dst" and >>>>>> return an address that is guaranteed to be safely callable. >>>>>> >>>>>> In the future, architectures hoping to make use of the sram-exec >>>>>> functionality must define an fncpy macro just as ARM has done to >>>>>> guarantee or check for safe copying to executable memory before allowing >>>>>> the arch to select CONFIG_SRAM_EXEC. >>>>>> >>>>>> Signed-off-by: Dave Gerlach >>>>> >>>>> Looks a lot saner, thanks. It's just a bit sad that we lose the type >>>>> checking. >>>>> >>>>> Acked-by: Russell King >>>> >>>> Looks like this is still pending so I'll add it into >>>> omap-for-v4.12/fixes so we can get this out of the way. >>> >>> It's a "fix"? Looked to be a 4.13 issue, sorry for the delay, otherwise >>> I would have queued it up earlier. >> >> Technically, it is a fix, but my greps for "sram_exec_copy" indicate >> that the code does not yet have any in-tree users. So I don't think >> there's any urgency to picking this up, and I think no need to back >> port to stable trees. > > OK fine, I'll drop it today from my fixes (and for-next) no problem. > I did add a fixes tag to it which would then create confusion later > on too with stable trees. > > Dave, probably best to resend the patch to Greg in few days with acks > added and rebased against v4.12-rc1 because it won't apply without a > merge because of the header changes. Yes, there are no users yet. Was planning on resending this anyway, so I'll do that before I send my patches that make use of this. Regards, Dave > > Regards, > > Tony > > > > > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: d-gerlach@ti.com (Dave Gerlach) Date: Wed, 17 May 2017 09:23:17 -0500 Subject: [PATCH v2] misc: sram-exec: Use aligned fncpy instead of memcpy In-Reply-To: <20170517134734.GA10818@atomide.com> References: <20170410145247.6023-1-d-gerlach@ti.com> <20170503185533.GS23750@n2100.armlinux.org.uk> <20170516160127.GH31418@atomide.com> <20170517091317.GA17902@kroah.com> <20170517114307.GU23750@n2100.armlinux.org.uk> <20170517134734.GA10818@atomide.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/17/2017 08:47 AM, Tony Lindgren wrote: > * Russell King - ARM Linux [170517 04:46]: >> On Wed, May 17, 2017 at 11:13:17AM +0200, Greg Kroah-Hartman wrote: >>> On Tue, May 16, 2017 at 09:01:27AM -0700, Tony Lindgren wrote: >>>> * Russell King - ARM Linux [170503 11:58]: >>>>> On Mon, Apr 10, 2017 at 09:52:47AM -0500, Dave Gerlach wrote: >>>>>> Currently the sram-exec functionality, which allows allocation of >>>>>> executable memory and provides an API to move code to it, is only >>>>>> selected in configs for the ARM architecture. Based on commit >>>>>> 5756e9dd0de6 ("ARM: 6640/1: Thumb-2: Symbol manipulation macros for >>>>>> function body copying") simply copying a C function pointer address >>>>>> using memcpy without consideration of alignment and Thumb is unsafe on >>>>>> ARM platforms. >>>>>> >>>>>> The aforementioned patch introduces the fncpy macro which is a safe way >>>>>> to copy executable code on ARM platforms, so let's make use of that here >>>>>> rather than the unsafe plain memcpy that was previously used by >>>>>> sram_exec_copy. Now sram_exec_copy will move the code to "dst" and >>>>>> return an address that is guaranteed to be safely callable. >>>>>> >>>>>> In the future, architectures hoping to make use of the sram-exec >>>>>> functionality must define an fncpy macro just as ARM has done to >>>>>> guarantee or check for safe copying to executable memory before allowing >>>>>> the arch to select CONFIG_SRAM_EXEC. >>>>>> >>>>>> Signed-off-by: Dave Gerlach >>>>> >>>>> Looks a lot saner, thanks. It's just a bit sad that we lose the type >>>>> checking. >>>>> >>>>> Acked-by: Russell King >>>> >>>> Looks like this is still pending so I'll add it into >>>> omap-for-v4.12/fixes so we can get this out of the way. >>> >>> It's a "fix"? Looked to be a 4.13 issue, sorry for the delay, otherwise >>> I would have queued it up earlier. >> >> Technically, it is a fix, but my greps for "sram_exec_copy" indicate >> that the code does not yet have any in-tree users. So I don't think >> there's any urgency to picking this up, and I think no need to back >> port to stable trees. > > OK fine, I'll drop it today from my fixes (and for-next) no problem. > I did add a fixes tag to it which would then create confusion later > on too with stable trees. > > Dave, probably best to resend the patch to Greg in few days with acks > added and rebased against v4.12-rc1 because it won't apply without a > merge because of the header changes. Yes, there are no users yet. Was planning on resending this anyway, so I'll do that before I send my patches that make use of this. Regards, Dave > > Regards, > > Tony > > > > > >