[U-Boot] [PATCH v7 07/17] ARM: Put target PC for PSCI CPU_ON on per-CPU stack

[Jan Kiszka]

On 2015-05-13 09:21, Wang Dongsheng wrote:
> 
> 
>> -----Original Message-----
>> From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Jan Kiszka
>> Sent: Tuesday, April 21, 2015 1:19 PM
>> To: U-Boot Mailing List; Tom Rini
>> Cc: Marc Zyngier; Tom Warren; Paul Walmsley; Ian Campbell; Thierry Reding
>> Subject: [U-Boot] [PATCH v7 07/17] ARM: Put target PC for PSCI CPU_ON on per-CPU
>> stack
>>
>> Use a per-CPU variable for saving the target PC during CPU_ON operations. This
>> allows us to run this service independently on targets that have more than 2
>> cores and also core-local power control.
>>
>> CC: Marc Zyngier <marc.zyngier at arm.com>
>> Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
>> Reviewed-by: Tom Rini <trini at konsulko.com>
>> Reviewed-by: Thierry Reding <treding at nvidia.com>
>> Tested-by: Thierry Reding <treding at nvidia.com>
>> Tested-by: Ian Campbell <ijc at hellion.org.uk>
>> ---
>>  arch/arm/cpu/armv7/psci.S       | 11 +++++------
>>  arch/arm/cpu/armv7/sunxi/psci.S |  9 ++++++---
>>  2 files changed, 11 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S index
>> 18d85c4..87c0c0b 100644
>> --- a/arch/arm/cpu/armv7/psci.S
>> +++ b/arch/arm/cpu/armv7/psci.S
>> @@ -17,6 +17,7 @@
>>
>>  #include <config.h>
>>  #include <linux/linkage.h>
>> +#include <asm/macro.h>
>>  #include <asm/psci.h>
>>
>>  	.pushsection ._secure.text, "ax"
>> @@ -202,6 +203,7 @@ ENTRY(psci_get_cpu_stack_top)
>>  	add	r5, r5, #0x2000			@ Skip two pages
>>  	lsr	r5, r5, #12			@ Align to start of page
>>  	lsl	r5, r5, #12
>> +	sub	r5, r5, #4			@ reserve 1 word for target PC
>>  	sub	r0, r5, r0			@ here's our stack!
>>
>>  	bx	lr
>> @@ -212,13 +214,10 @@ ENTRY(psci_cpu_entry)
>>
>>  	bl	_nonsec_init
>>
>> -	adr	r0, _psci_target_pc
>> -	ldr	r0, [r0]
>> +	bl	psci_get_cpu_id			@ CPU ID => r0
>> +	bl	psci_get_cpu_stack_top		@ stack top => r0
>> +	ldr	r0, [r0]			@ target PC at stack top
>>  	b	_do_nonsec_entry
>>  ENDPROC(psci_cpu_entry)
>>
>> -.globl _psci_target_pc
>> -_psci_target_pc:
>> -	.word	0
>> -
>>  	.popsection
>> diff --git a/arch/arm/cpu/armv7/sunxi/psci.S b/arch/arm/cpu/armv7/sunxi/psci.S
>> index dd583b2..7ec0500 100644
>> --- a/arch/arm/cpu/armv7/sunxi/psci.S
>> +++ b/arch/arm/cpu/armv7/sunxi/psci.S
>> @@ -139,8 +139,11 @@ out:	mcr	p15, 0, r7, c1, c1, 0
>>  	@ r2 = target PC
>>  .globl	psci_cpu_on
>>  psci_cpu_on:
>> -	ldr	r0, =_psci_target_pc
>> -	str	r2, [r0]
>> +	push	{lr}
>> +
>> +	mov	r0, r1
>> +	bl	psci_get_cpu_stack_top	@ get stack top of target CPU
>> +	str	r2, [r0]		@ store target PC at stack top
> 
> Base on target PC will be saved in stack. The cpu(r1) should be mask firstly.
> Because r1 value is 0xf0x, and it is not what we expected cpu value(0x1 or ...).
> If not, the stack address is incorrect.
> 
> When I develop LS1021a PSCI code, I found this issue. So I think sunxi also has this
> issue.

IIRC, sunxi has no clusters != 0 so far, but you are right conceptually.
We already mask elsewhere in that function, so the instruction should
simply be moved up here.

Jan

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