[PATCH] perf: Fix unexported generic perf_arch_fetch_caller_regs

[Frederic Weisbecker <fweisbec@gmail.com>]

perf_arch_fetch_caller_regs() is exported for the overriden x86
version, but not for the generic weak version.
As a general rule, weak functions should have their symbol exported
in the same file they are defined.

So let's export it on trace_event_perf.c as it is used by trace
events only.

This fixes:
	ERROR: ".perf_arch_fetch_caller_regs" [fs/xfs/xfs.ko] undefined!
	ERROR: ".perf_arch_fetch_caller_regs" [arch/powerpc/platforms/cell/spufs/spufs.ko] undefined!

And also only build it if trace events are enabled.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/x86/kernel/cpu/perf_event.c |    1 -
 kernel/trace/trace_event_perf.c  |    2 ++
 2 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 7645fae..5fb490c 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1713,4 +1713,3 @@ void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int ski
 	regs->cs = __KERNEL_CS;
 	local_save_flags(regs->flags);
 }
-EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 0709e4f..7d79a10 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -12,6 +12,8 @@
 DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
 EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
 
+EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
+
 static char *perf_trace_buf;
 static char *perf_trace_buf_nmi;
 
-- 
1.6.2.3