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

[Brad Figg]

On Mon, Dec 8, 2014 at 8:53 AM, Chris J Arges <chris.j.arges at canonical.com>
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>
> ---
>  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 516d67c..4b65a7f 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -292,10 +292,10 @@ static inline void disable_surveillance(void)
>         args.token = rtas_token("set-indicator");
>         if (args.token == RTAS_UNKNOWN_SERVICE)
>                 return;
> -       args.nargs = 3;
> -       args.nret = 1;
> +       args.nargs = cpu_to_be32(3);
> +       args.nret = cpu_to_be32(1);
>         args.rets = &args.args[3];
> -       args.args[0] = SURVEILLANCE_TOKEN;
> +       args.args[0] = cpu_to_be32(SURVEILLANCE_TOKEN);
>         args.args[1] = 0;
>         args.args[2] = 0;
>         enter_rtas(__pa(&args));
> --
> 1.9.1
>
>
> --
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>
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