linux-kernel - Re: [PATCH v2] PowerPC: kernel: compiling issue, make additional room in exception vector area

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Date:	Fri, 26 Apr 2013 09:36:35 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Michael Neuling <mikey@...ling.org>
CC:	Mike Qiu <qiudayu@...ux.vnet.ibm.com>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <michael@...erman.id.au>,
	linuxppc-dev@...ts.ozlabs.org, sfr@...b.auug.org.au,
	matt@...abs.org, linux-kernel@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2] PowerPC: kernel: compiling issue, make additional
 room in exception vector area

On 2013年04月26日 09:18, Chen Gang wrote:
> On 2013年04月26日 09:06, Chen Gang wrote:
>>> CFAR is the Come From Register.  It saves the location of the last
>>>> branch and is hence overwritten by any branch.
>>>>
>> Do we process it just like others done (e.g. 0x300, 0xe00, 0xe20 ...) ?
>> 	. = 0x900
>> 	.globl decrementer_pSeries
>> decrementer_pSeries:
>>  	HMT_MEDIUM_PPR_DISCARD
>> 	SET_SCRATCH0(r13)
>> 	b decrementer_pSeries_0
>>
>> 	...
>>
>>

Oh, it seems EXCEPTION_PROLOG_1 will save the regesters which related
with CFAR, so I think need move EXCEPTION_PROLOG_1 to near 0x900.

---------------------------------diff v2 begin-----------------------------

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e789ee7..f0489c4 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -254,7 +254,15 @@ hardware_interrupt_hv:
 	STD_EXCEPTION_PSERIES(0x800, 0x800, fp_unavailable)
 	KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0x800)
 
-	MASKABLE_EXCEPTION_PSERIES(0x900, 0x900, decrementer)
+	. = 0x900
+	.globl decrementer_pSeries
+decrementer_pSeries:
+	HMT_MEDIUM_PPR_DISCARD
+	SET_SCRATCH0(r13)		/* save r13 */
+	EXCEPTION_PROLOG_0(PACA_EXGEN)
+	EXCEPTION_PROLOG_1(PACA_EXGEN, SOFTEN_TEST_PR, 0x900)
+	b	decrementer_pSeries_0
+
 	STD_EXCEPTION_HV(0x980, 0x982, hdecrementer)
 
 	MASKABLE_EXCEPTION_PSERIES(0xa00, 0xa00, doorbell_super)
@@ -536,6 +544,11 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_206)
 #endif
 
 	.align	7
+	/* moved from 0x900 */
+decrementer_pSeries_0:
+	EXCEPTION_PROLOG_PSERIES_1(decrementer_common, EXC_STD)
+
+	.align	7
 	/* moved from 0xe00 */
 	STD_EXCEPTION_HV_OOL(0xe02, h_data_storage)
 	KVM_HANDLER_SKIP(PACA_EXGEN, EXC_HV, 0xe02)


---------------------------------diff v2 end-------------------------------


> 
> Such as the fix below, is it OK (just like 0x300 or 0x200 has done) ?
> 
> Please check, thanks.
> 
> ---------------------------diff begin-------------------------------------
> 
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index e789ee7..a0a5ff2 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -254,7 +254,14 @@ hardware_interrupt_hv:
>  	STD_EXCEPTION_PSERIES(0x800, 0x800, fp_unavailable)
>  	KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0x800)
>  
> -	MASKABLE_EXCEPTION_PSERIES(0x900, 0x900, decrementer)
> +	. = 0x900
> +	.globl decrementer_pSeries
> +decrementer_pSeries:
> +	HMT_MEDIUM_PPR_DISCARD
> +	SET_SCRATCH0(r13)		/* save r13 */
> +	EXCEPTION_PROLOG_0(PACA_EXGEN)
> +	b	decrementer_pSeries_0
> +
>  	STD_EXCEPTION_HV(0x980, 0x982, hdecrementer)
>  
>  	MASKABLE_EXCEPTION_PSERIES(0xa00, 0xa00, doorbell_super)
> @@ -536,6 +543,12 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_206)
>  #endif
>  
>  	.align	7
> +	/* moved from 0x900 */
> +decrementer_pSeries_0:
> +	EXCEPTION_PROLOG_1(PACA_EXGEN, SOFTEN_TEST_PR, 0x900)
> +	EXCEPTION_PROLOG_PSERIES_1(decrementer_common, EXC_STD)
> +
> +	.align	7
>  	/* moved from 0xe00 */
>  	STD_EXCEPTION_HV_OOL(0xe02, h_data_storage)
>  	KVM_HANDLER_SKIP(PACA_EXGEN, EXC_HV, 0xe02)
> 
> ---------------------------diff end---------------------------------------
> 


-- 
Chen Gang

Asianux Corporation
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