[PATCH powerpc] Fix parameter restoring issue in commit 752a6422f

[Mike Qiu]

Hi Zhong,

I really need this patch :)

BTW, it seems that this bug just happens in 3.16-rc1 as I reported.

Thanks
Mike

On 06/25/2014 12:00 PM, Li Zhong wrote:
> In commit 752a6422f, new stack frame is created for parameters.
>
> However, the r1 is added back a little earlier, so r3 and r4 are
> restored from a wrong place, which could cause following error during
> boot:
>
> Querying for OPAL presence...  there !
> DEFAULT CATCH!, exception-handler=fff00700
> at   %SRR0: 0000000004223058   %SRR1: 8000000000081002
> Open Firmware exception handler entered from non-OF code
>
> Client's Fix Pt Regs:
>   00 0000000004223054 0000000004223020 0000000004fbe838 0000000000000002
>   04 0000000028002024 0000000004fbe838 000000000427e838 0000000004222f20
>   08 0000000000000000 0000000000000000 0000000004222f20 0000000000001002
>   0c a000000000000001 0000000000000000 0000000001a3fd20 00000000040eb170
>   10 00000000040eb628 00000000040eb368 fffffffffffffffd 0000000001a3fd20
>   14 0000000001b37f00 000000000f340000 0000000000cc0000 000000000f340000
>   18 00000000040ebb08 0000000003580000 00000000040eb128 0000000004285920
>   1c 0000000001a3fd60 00000000040eb100 7c0802a6f8010010 f821ff914b91ebd1
> Special Regs:
>      %IV: 00000700     %CR: 28002022    %XER: 00000000  %DSISR: 42000000
>    %SRR0: 0000000004223058   %SRR1: 8000000000081002
>      %LR: 0000000004223054    %CTR: 0000000000000000
>     %DAR: 01a3fcf00020b4ac
> Virtual PID = 0
>   ok
>
> Signed-off-by: Li Zhong <zhong at linux.vnet.ibm.com>
> ---
> diff --git a/arch/powerpc/platforms/powernv/opal-takeover.S b/arch/powerpc/platforms/powernv/opal-takeover.S
> index 11a3169..9093540 100644
> --- a/arch/powerpc/platforms/powernv/opal-takeover.S
> +++ b/arch/powerpc/platforms/powernv/opal-takeover.S
> @@ -5,6 +5,7 @@
>    *
>    * This program is free software; you can redistribute it and/or
>    * modify it under the terms of the GNU General Public License
> +B
>    * as published by the Free Software Foundation; either version
>    * 2 of the License, or (at your option) any later version.
>    */
> @@ -27,11 +28,11 @@ _GLOBAL(opal_query_takeover)
>   	li	r3,H_HAL_TAKEOVER
>   	li	r4,H_HAL_TAKEOVER_QUERY_MAGIC
>   	HVSC
> -	addi	r1,r1,STACKFRAMESIZE
>   	ld	r10,STK_PARAM(R3)(r1)
>   	std	r4,0(r10)
>   	ld	r10,STK_PARAM(R4)(r1)
>   	std	r5,0(r10)
> +	addi	r1,r1,STACKFRAMESIZE
>   	lwz	r0,8(r1)
>   	mtcrf	0xff,r0
>   	blr
>
>
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