[PATCH] perf: Fix build break on powerpc due to sample_reg_masks

[Sukadev Bhattiprolu]

>From d1171a4c34c6100ec8b663ddb803dd69ef3fb7ce Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
Date: Thu, 24 Sep 2015 17:53:49 -0400
Subject: [PATCH] perf: Fix build break on powerpc due to sample_reg_masks

perf_regs.c does not get built on Powerpc as CONFIG_PERF_REGS is false.
So the weak definition for 'sample_regs_masks' doesn't get picked up.

Adding perf_regs.o to util/Build unconditionally, exposes a redefinition
error for 'perf_reg_value()' function (due to the static inline version
in util/perf_regs.h). So use #ifdef HAVE_PERF_REGS_SUPPORT' around that
function.

Signed-off-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
---
 tools/perf/util/Build       | 2 +-
 tools/perf/util/perf_regs.c | 2 ++
 tools/perf/util/perf_regs.h | 4 ++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 349bc96..e5f18a2 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -17,6 +17,7 @@ libperf-y += levenshtein.o
 libperf-y += llvm-utils.o
 libperf-y += parse-options.o
 libperf-y += parse-events.o
+libperf-y += perf_regs.o
 libperf-y += path.o
 libperf-y += rbtree.o
 libperf-y += bitmap.o
@@ -103,7 +104,6 @@ libperf-$(CONFIG_LIBBABELTRACE) += data-convert-bt.o
 
 libperf-y += scripting-engines/
 
-libperf-$(CONFIG_PERF_REGS) += perf_regs.o
 libperf-$(CONFIG_ZLIB) += zlib.o
 libperf-$(CONFIG_LZMA) += lzma.o
 
diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c
index 885e8ac..6b8eb13 100644
--- a/tools/perf/util/perf_regs.c
+++ b/tools/perf/util/perf_regs.c
@@ -6,6 +6,7 @@ const struct sample_reg __weak sample_reg_masks[] = {
 	SMPL_REG_END
 };
 
+#ifdef HAVE_PERF_REGS_SUPPORT
 int perf_reg_value(u64 *valp, struct regs_dump *regs, int id)
 {
 	int i, idx = 0;
@@ -29,3 +30,4 @@ out:
 	*valp = regs->cache_regs[id];
 	return 0;
 }
+#endif
diff --git a/tools/perf/util/perf_regs.h b/tools/perf/util/perf_regs.h
index 2984dcc..8dbdfeb 100644
--- a/tools/perf/util/perf_regs.h
+++ b/tools/perf/util/perf_regs.h
@@ -3,6 +3,10 @@
 
 #include <linux/types.h>
 
+#ifndef __maybe_unused
+#define __maybe_unused __attribute__((unused))
+#endif
+
 struct regs_dump;
 
 struct sample_reg {
-- 
1.8.3.1