linux-kernel - Re: [PATCH] pseries/le: Fix endiannes issue in RTAS call from xmon

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Date:	Thu, 15 Jan 2015 15:25:50 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Laurent Dufour <ldufour@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	benh@...nel.crashing.org, paulus@...ba.org
Subject: Re: [PATCH] pseries/le: Fix endiannes issue in RTAS call from xmon

On Mon, 2014-11-24 at 15:07 +0100, Laurent Dufour wrote:
> On pseries system (LPAR) xmon failed to enter when running in LE mode, system
> is hunging. Inititating xmon will lead to such an output on the console:
> 
> SysRq : Entering xmon
> cpu 0x15: Vector: 0  at [c0000003f39ffb10]
>     pc: c00000000007ed7c: sysrq_handle_xmon+0x5c/0x70
>     lr: c00000000007ed7c: sysrq_handle_xmon+0x5c/0x70
>     sp: c0000003f39ffc70
>    msr: 8000000000009033
>   current = 0xc0000003fafa7180
>   paca    = 0xc000000007d75e80	 softe: 0	 irq_happened: 0x01
>     pid   = 14617, comm = bash
> Bad kernel stack pointer fafb4b0 at eca7cc4
> cpu 0x15: Vector: 300 (Data Access) at [c000000007f07d40]
>     pc: 000000000eca7cc4
>     lr: 000000000eca7c44
>     sp: fafb4b0
>    msr: 8000000000001000
>    dar: 10000000
>  dsisr: 42000000
>   current = 0xc0000003fafa7180
>   paca    = 0xc000000007d75e80	 softe: 0	 irq_happened: 0x01
>     pid   = 14617, comm = bash
> cpu 0x15: Exception 300 (Data Access) in xmon, returning to main loop
> xmon: WARNING: bad recursive fault on cpu 0x15
> 
> The root cause is that xmon is calling RTAS to turn off the surveillance
> when entering xmon, and RTAS is requiring big endian parameters.
> 
> This patch is byte swapping the RTAS arguments when running in LE mode.
> 
> Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/xmon/xmon.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index b988b5addf86..c8efbb37d6e0 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -293,10 +293,10 @@ static inline void disable_surveillance(void)
>  	args.token = rtas_token("set-indicator");
>  	if (args.token == RTAS_UNKNOWN_SERVICE)
>  		return;

I just noticed we're not handling the token correctly here. It is be32 also.

cheers


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