Subject: [PATCH] ARM: keystone: remove hand-coded smc instruction

From: [email-masked] (Santosh Shilimkar)
Date: Tue, 25 Jun 2013 10:27:11 -0400

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 <[email-masked]>
>> 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 <[email-masked]>
>>
>> Signed-off-by: Santosh Shilimkar <[email-masked]>
>> ---

[..]

>> diff --git a/arch/arm/mach-keystone/smc.S b/arch/arm/mach-keystone/smc.S
>> new file mode 100644
>> index 0000000..9b9e4f7
>> --- /dev/null
>> +++ b/arch/arm/mach-keystone/smc.S
>> @@ -0,0 +1,29 @@
>> +/*
>> + * Keystone Secure APIs
>> + *
>> + * Copyright (C) 2013 Texas Instruments, Inc.
>> + * 	Santosh Shilimkar <[email-masked]>
>> + *
>> + * This program is free software,you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/linkage.h>
>> +
>> +/**
>> + * u32 keystone_cpu_smc(u32 command, u32 cpu, u32 addr)
>> + *
>> + * Low level CPU monitor API
>> + * @command:	Monitor command.
>> + * @cpu:	CPU Number
>> + * @addr:	Kernel jump address for boot CPU
>> + *
>> + * Return: Non zero value on failure
>> + */
> 
> Oops, looks like I missed the final mail on this thread.  Ignore my
> previous mail.
> 
> I still think it would be a good idea to try to consolidate all these
> trivial SMC wrappers, but this remains debatable.
> 
> 
> 
> 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.
I actually added it while moving it to asm file.
 
>> +	ldmfd   sp!, {r4-r12, pc}
>> +ENDPROC(keystone_cpu_smc)
> 
> r12 is caller-save btw; you don't need to preserve it.
> 
Indeed. Will update it while adding some more SMC APIs.
Its not harmful as such for now.

Regards,
Santosh