ftrace: powerpc clean ups

This patch cleans up the ftrace code in PowerPC based on the comments from
Michael Ellerman.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: proski@gnu.org
Cc: a.p.zijlstra@chello.nl
Cc: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: linuxppc-dev@ozlabs.org
Cc: Soeren Sandmann Pedersen <sandmann@redhat.com>
Cc: paulus@samba.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 5a4993fefa45..69ed41223468 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -51,10 +51,16 @@ notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
         static unsigned int op;
 
+        /*
+         * It would be nice to just use create_function_call, but that will
+         * update the code itself. Here we need to just return the
+         * instruction that is going to be modified, without modifying the
+         * code.
+         */
         addr = GET_ADDR(addr);
 
         /* Set to "bl addr" */
-        op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffe);
+        op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
 
         /*
          * No locking needed, this must be called via kstop_machine