powerpc/powernv: Fix opal_exit tracepoint opcode

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>

diff --git a/arch/powerpc/platforms/powernv/opal-wrappers.S b/arch/powerpc/platforms/powernv/opal-wrappers.S
index f7c19c9c57ed9f4bc1e0762332d79f20e4e1308e..63fe1b2b11755f7c942ece5eeeba90c15e45563c 100644 (file)
--- a/arch/powerpc/platforms/powernv/opal-wrappers.S
+++ b/arch/powerpc/platforms/powernv/opal-wrappers.S
@@ -146,7 +146,7 @@ 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