ACK: [Utopic/Trusty][SRU][PATCH] powerpc/pseries: Fix endiannes issue in RTAS call from xmon

[Seth Forshee]

On Mon, Dec 08, 2014 at 10:53:50AM -0600, Chris J Arges wrote:
> From: Laurent Dufour <ldufour at linux.vnet.ibm.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1396235
> 
> 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.
> 
> Cc: stable at vger.kernel.org
> Signed-off-by: Laurent Dufour <ldufour at linux.vnet.ibm.com>
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> (cherry picked from commit 3b8a3c01096925a824ed3272601082289d9c23a5)
> Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>

Straightforward and an upstrem cherry pick, and no regression potential
for any other arches.

Acked-by: Seth Forshee <seth.forshee at canonical.com>