2014-11-24 14:08:13

by Laurent Dufour

Subject: [PATCH] pseries/le: Fix endiannes issue in RTAS call from xmon

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 <[email protected]>
---
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;
- 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

2014-11-26 03:31:40

by Michael Ellerman

Subject: Re: pseries/le: Fix endiannes issue in RTAS call from xmon

On Mon, 2014-24-11 at 14:07:53 UTC, 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:

OK. You say "LPAR", by which you mean "under phyp" I think. I haven't seen this
under KVM, and it looks like KVM doesn't implement "set-indicator" so that
would explain that.

I'll take this as a bug fix and CC it to stable.

cheers

2014-11-26 08:19:53

by Laurent Dufour

Subject: Re: pseries/le: Fix endiannes issue in RTAS call from xmon

On 26/11/2014 04:31, Michael Ellerman wrote:
> OK. You say "LPAR", by which you mean "under phyp" I think. I haven't seen this
> under KVM, and it looks like KVM doesn't implement "set-indicator" so that
> would explain that.

Yes LPAR implies phyp, and KVM don't implement "set-indicator" so this
doesn't happen in that case.

> I'll take this as a bug fix and CC it to stable.

That's a good point.

Thanks,
Laurent.