powerpc/powernv: Fix opal_exit tracepoint opcode

commit a7e0fb6c2029a780444d09560f739e020d54fe4d upstream.

Currently the opal_exit tracepoint usually shows the opcode as 0:

  <idle>-0     [047] d.h.   635.654292: opal_entry: opcode=63
  <idle>-0     [047] d.h.   635.654296: opal_exit: opcode=0 retval=0
  kopald-1209  [019] d...   636.420943: opal_entry: opcode=10
  kopald-1209  [019] d...   636.420959: opal_exit: opcode=0 retval=0

This is because we incorrectly load the opcode into r0 before calling
__trace_opal_exit(), whereas it expects the opcode in r3 (first function
parameter). In fact we are leaving the retval in r3, so opcode and
retval will always show the same value.

Instead load the opcode into r3, resulting in:

  <idle>-0     [040] d.h.   636.618625: opal_entry: opcode=63
  <idle>-0     [040] d.h.   636.618627: opal_exit: opcode=63 retval=0

Fixes: c49f63530bb6 ("powernv: Add OPAL tracepoints")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index b67ea67eb71b32d0b6e15b00948edb08a806ec55..4350b7bc94f57e67a3541cd20adc2ff452b38f3f 100644 (file)
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -148,7 +148,7 @@ opal_tracepoint_entry:
 opal_tracepoint_return:
        std     r3,STK_REG(R31)(r1)
        mr      r4,r3
-       ld      r0,STK_REG(R23)(r1)
+       ld      r3,STK_REG(R23)(r1)
        bl      __trace_opal_exit
        ld      r3,STK_REG(R31)(r1)
        addi    r1,r1,STACKFRAMESIZE