[PATCH 3.14 31/73] powerpc/pseries: Fix endiannes issue in RTAS call from xmon

From: Greg Kroah-Hartman
Date: Fri Dec 05 2014 - 18:24:35 EST

3.14-stable review patch. If anyone has any objections, please let me know.


From: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx>

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

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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/xmon/xmon.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -288,10 +288,10 @@ static inline void disable_surveillance(
args.token = rtas_token("set-indicator");
if (args.token == RTAS_UNKNOWN_SERVICE)
- 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;

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