[3.13.y-ckt stable] Patch "powerpc/pseries: Fix endiannes issue in RTAS call from xmon" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    powerpc/pseries: Fix endiannes issue in RTAS call from xmon

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt13.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 53481f7f04500d50a49fed0fe9944ee88dbd6398 Mon Sep 17 00:00:00 2001
From: Laurent Dufour <ldufour at linux.vnet.ibm.com>
Date: Mon, 24 Nov 2014 15:07:53 +0100
Subject: powerpc/pseries: Fix endiannes issue in RTAS call from xmon

commit 3b8a3c01096925a824ed3272601082289d9c23a5 upstream.

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 at linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Kamal Mostafa <kamal 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 af9d346..4898203 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -288,10 +288,10 @@ 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