From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@ti.com (Santosh Shilimkar) Date: Tue, 25 Jun 2013 11:51:13 -0400 Subject: [PATCH] ARM: keystone: remove hand-coded smc instruction In-Reply-To: <20130625153929.GG2327@linaro.org> References: <201306212228.29717.arnd@arndb.de> <201306212313.16771.arnd@arndb.de> <51C4C3B4.2050508@ti.com> <201306212341.08579.arnd@arndb.de> <51C4D9B7.5010109@ti.com> <20130625141332.GC2327@linaro.org> <51C9A8BF.9040602@ti.com> <20130625143211.GE2327@linaro.org> <51C9ABF9.1010902@ti.com> <20130625153929.GG2327@linaro.org> Message-ID: <51C9BC71.1000503@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 25 June 2013 11:39 AM, Dave Martin wrote: > On Tue, Jun 25, 2013 at 10:40:57AM -0400, Santosh Shilimkar wrote: >> On Tuesday 25 June 2013 10:32 AM, Dave Martin wrote: >>> On Tue, Jun 25, 2013 at 10:27:11AM -0400, Santosh Shilimkar wrote: >>>> On Tuesday 25 June 2013 10:13 AM, Dave Martin wrote: >>>>> On Fri, Jun 21, 2013 at 06:54:47PM -0400, Santosh Shilimkar wrote: >>>>>> On Friday 21 June 2013 05:41 PM, Arnd Bergmann wrote: >>>>>>> On Friday 21 June 2013, Santosh Shilimkar wrote: >>>>>>>>> >>>>>>>> I was curious how you will fix that for a c file. >>>>>>>> Just to be clear, I was planning to do that in 3.11-rcx/3.12 >>>>>>>> time. Let me know if it needs to be done earlier than that. >>>>>>> >>>>>>> It breaks randconfig builds on arm-soc at the moment, so I'd >>>>>>> like the fix as early as possible for 3.11. >>>>>>> >>>>>> Ok, fix is at end of the email. Let me know if it makes >>>>>> to pass both the builds now. I have build and boot tested >>>>>> both ARM and THUMB2 builds on Keystone board. >>>>>> >>>>>> Regards, >>>>>> Santosh >>>>>> >>>>>> From 05d6a5b6cad624fb3791e8c1f8eb7c774f0790d9 Mon Sep 17 00:00:00 2001 >>>>>> From: Santosh Shilimkar >>>>>> Date: Fri, 21 Jun 2013 18:35:32 -0400 >>>>>> Subject: [PATCH] ARM: keystone: Move CPU bringup code to dedicated asm file >>>>>> >>>>>> Because of inline asm usage in platsmp.c, smc instruction >>>>>> creates build failure for ARM V6+V7 build where as using instruction >>>>>> encoding for smc breaks the thumb2 build. >>>>>> >>>>>> So move the code snippet to separate asm file and mark >>>>>> it with 'armv7-a$(plus_sec)' to avoid any build issues. >>>>>> >>>>>> Cc: Arnd Bergmann >>>>>> >>>>>> Signed-off-by: Santosh Shilimkar >>>>>> --- [..] >>>>> Anyway, this looks like it should work, except: >>>>> >>>>>> +ENTRY(keystone_cpu_smc) >>>>>> + stmfd sp!, {r4-r12, lr} >>>>>> + smc #0 >>>>>> + dsb >>>>> >>>>> What's this DSB for? (You didn't have it in the inline asm version) >>>>> >>>> Just to drain the write buffer before resuming on non-secure side. >>> >>> Why do you need to do that? >>> >> To commit any secure side pending writes. I don't remember exactly the >> issues but I remember facing issues in power management sequencing with >> SMC calls in between. That time a dsb did the trick. In fact I use to >> keep 1 before SMC and 1 after. > > Can we at least have a comment (as recommended in > Documentation/development-process/4.Coding)? > > We don't want other people reading this and concluding that SMC always > needs barriers -- in general, this shouldn't be necessary and could > indicate bugs lurking somewhere. > Agree. Comment should have been there to avoid confusion. Will do. Regards, Santosh