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>

5 files changed, 14 insertions, 20 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 0e6221889ca9..3b1dd29d9f91 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1129,18 +1129,11 @@ _GLOBAL(_mcount)
         stw     r5, 8(r1)
 
         LOAD_REG_ADDR(r5, ftrace_trace_function)
-#if 0
-        mtctr   r3
-        mr      r1, r5
-        bctrl
-#endif
         lwz     r5,0(r5)
-#if 1
+
         mtctr   r5
         bctrl
-#else
-        bl      ftrace_stub
-#endif
+
         nop
 
         lwz     r6, 8(r1)
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
diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index cf6b5a7d8b3f..4300db52662a 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -43,6 +43,7 @@
 #include <asm/div64.h>
 #include <asm/signal.h>
 #include <asm/dcr.h>
+#include <asm/ftrace.h>
 
 #ifdef CONFIG_PPC32
 extern void transfer_to_handler(void);
@@ -68,6 +69,10 @@ EXPORT_SYMBOL(single_step_exception);
 EXPORT_SYMBOL(sys_sigreturn);
 #endif
 
+#ifdef CONFIG_FTRACE
+EXPORT_SYMBOL(_mcount);
+#endif
+
 EXPORT_SYMBOL(strcpy);
 EXPORT_SYMBOL(strncpy);
 EXPORT_SYMBOL(strcat);
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 22f8e2bacd32..19e8fcb9cea8 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -47,11 +47,6 @@
 #include <asm/kgdb.h>
 #endif
 
-#ifdef CONFIG_FTRACE
-extern void _mcount(void);
-EXPORT_SYMBOL(_mcount);
-#endif
-
 extern void bootx_init(unsigned long r4, unsigned long phys);
 
 int boot_cpuid;
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 277bf18cbbcc..098fd96a394a 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -85,11 +85,6 @@ struct ppc64_caches ppc64_caches = {
 };
 EXPORT_SYMBOL_GPL(ppc64_caches);
 
-#ifdef CONFIG_FTRACE
-extern void _mcount(void);
-EXPORT_SYMBOL(_mcount);
-#endif
-
 /*
  * These are used in binfmt_elf.c to put aux entries on the stack
  * for each elf executable being started.