linux-kernel - [PATCH 2/3] perf tools: Add dedicated unwind addr

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Message-Id: <1460013073-18444-2-git-send-email-jolsa@kernel.org>
Date:	Thu,  7 Apr 2016 09:11:12 +0200
From:	Jiri Olsa <jolsa@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andreas Hollmann <hollmann@...tum.de>,
	Milian Wolff <milian.wolff@...b.com>
Subject: [PATCH 2/3] perf tools: Add dedicated unwind addr_space member into thread struct

Milian reported issue with thread::priv, which was double
booked by perf trace and DWARF unwind code. So using those
together is impossible at the moment.

Moving DWARF unwind private data into separate variable
so perf trace can keep using thread::priv.

Reported-by: Milian Wolff <milian.wolff@...b.com>
Link: http://lkml.kernel.org/n/tip-pwiici9lf2l0iuji1jv1f5kx@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/util/thread.h           |  6 ++++++
 tools/perf/util/unwind-libunwind.c | 25 +++++++++----------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index a0ac0317affb..e214207bb13a 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -9,6 +9,9 @@
 #include "symbol.h"
 #include <strlist.h>
 #include <intlist.h>
+#ifdef HAVE_LIBUNWIND_SUPPORT
+#include <libunwind.h>
+#endif
 
 struct thread_stack;
 
@@ -32,6 +35,9 @@ struct thread {
 
 	void			*priv;
 	struct thread_stack	*ts;
+#ifdef HAVE_LIBUNWIND_SUPPORT
+	unw_addr_space_t	addr_space;
+#endif
 };
 
 struct machine;
diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index ee7e372297e5..63687d3a344e 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -32,6 +32,7 @@
 #include "symbol.h"
 #include "util.h"
 #include "debug.h"
+#include "asm/bug.h"
 
 extern int
 UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
@@ -580,43 +581,33 @@ static unw_accessors_t accessors = {
 
 int unwind__prepare_access(struct thread *thread)
 {
-	unw_addr_space_t addr_space;
-
 	if (callchain_param.record_mode != CALLCHAIN_DWARF)
 		return 0;
 
-	addr_space = unw_create_addr_space(&accessors, 0);
-	if (!addr_space) {
+	thread->addr_space = unw_create_addr_space(&accessors, 0);
+	if (!thread->addr_space) {
 		pr_err("unwind: Can't create unwind address space.\n");
 		return -ENOMEM;
 	}
 
-	unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL);
-	thread__set_priv(thread, addr_space);
-
+	unw_set_caching_policy(thread->addr_space, UNW_CACHE_GLOBAL);
 	return 0;
 }
 
 void unwind__flush_access(struct thread *thread)
 {
-	unw_addr_space_t addr_space;
-
 	if (callchain_param.record_mode != CALLCHAIN_DWARF)
 		return;
 
-	addr_space = thread__priv(thread);
-	unw_flush_cache(addr_space, 0, 0);
+	unw_flush_cache(thread->addr_space, 0, 0);
 }
 
 void unwind__finish_access(struct thread *thread)
 {
-	unw_addr_space_t addr_space;
-
 	if (callchain_param.record_mode != CALLCHAIN_DWARF)
 		return;
 
-	addr_space = thread__priv(thread);
-	unw_destroy_addr_space(addr_space);
+	unw_destroy_addr_space(thread->addr_space);
 }
 
 static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
@@ -639,7 +630,9 @@ static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
 	 * unwind itself.
 	 */
 	if (max_stack - 1 > 0) {
-		addr_space = thread__priv(ui->thread);
+		WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
+		addr_space = ui->thread->addr_space;
+
 		if (addr_space == NULL)
 			return -1;
 
-- 
2.4.11