linux-kernel - [PATCH v6 08/11] perf tools: Show warnings for unsupported cross-platform unwind

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Message-ID: <1464436800-39860-9-git-send-email-hekuang@huawei.com>
Date:	Sat, 28 May 2016 11:59:57 +0000
From:	He Kuang <hekuang@...wei.com>
To:	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
	<wangnan0@...wei.com>, <hekuang@...wei.com>, <jpoimboe@...hat.com>,
	<ak@...ux.intel.com>, <eranian@...gle.com>, <namhyung@...nel.org>,
	<adrian.hunter@...el.com>, <sukadev@...ux.vnet.ibm.com>,
	<masami.hiramatsu.pt@...achi.com>, <tumanova@...ux.vnet.ibm.com>,
	<kan.liang@...el.com>, <penberg@...nel.org>, <dsahern@...il.com>
CC:	<linux-kernel@...r.kernel.org>
Subject: [PATCH v6 08/11] perf tools: Show warnings for unsupported cross-platform unwind

Currently, perf script uses host unwind methods to parse perf.data
callchain info regardless of the target architecture. So we get wrong
result without any warnings when unwinding callchains of x86(32-bit)
on x86(64-bit) machine.

This patch shows warning messages when we do remote unwind x86(32-bit)
on other machines. Same thing for other platforms will be added in
next patches.

Signed-off-by: He Kuang <hekuang@...wei.com>
---
 tools/perf/config/Makefile         |  8 ++++++++
 tools/perf/util/thread.c           |  2 +-
 tools/perf/util/unwind-libunwind.c | 30 +++++++++++++++++++++++++++++-
 tools/perf/util/unwind.h           |  5 +++--
 4 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index 3a304a3..e156f76 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -355,6 +355,14 @@ endif
 
 ifndef NO_LIBUNWIND
   have_libunwind :=
+
+  ifeq ($(feature-libunwind-x86), 1)
+    $(call detected,CONFIG_LIBUNWIND_X86)
+    CFLAGS += -DHAVE_LIBUNWIND_X86_SUPPORT
+    LDFLAGS += -lunwind-x86
+    have_libunwind = 1
+  endif
+
   ifneq ($(feature-libunwind), 1)
     msg := $(warning No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR);
     NO_LOCAL_LIBUNWIND := 1
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 045477d..7ffee25 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -203,7 +203,7 @@ void thread__insert_map(struct thread *thread, struct map *map)
 	map_groups__fixup_overlappings(thread->mg, map, stderr);
 	map_groups__insert(thread->mg, map);
 
-	unwind__prepare_access(thread);
+	unwind__prepare_access(thread, map);
 }
 
 static int thread__clone_map_groups(struct thread *thread,
diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index 40d0453..037ee72 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -1,8 +1,36 @@
 #include "unwind.h"
 #include "thread.h"
+#include "session.h"
+#include "debug.h"
+#include "arch/common.h"
 
-int unwind__prepare_access(struct thread *thread)
+int unwind__prepare_access(struct thread *thread, struct map *map)
 {
+	const char *arch;
+	enum dso_type dso_type;
+
+	if (!thread->mg->machine->env)
+		return -1;
+
+	dso_type = dso__type(map->dso, thread->mg->machine);
+	if (dso_type == DSO__TYPE_UNKNOWN)
+		return -1;
+
+	if (thread->addr_space)
+		pr_debug("unwind: thread map already set, 64bit is %d, dso=%s\n",
+			 dso_type == DSO__TYPE_64BIT, map->dso->name);
+
+	arch = normalize_arch(thread->mg->machine->env->arch);
+
+	if (!strcmp(arch, "x86")) {
+		if (dso_type != DSO__TYPE_64BIT)
+#ifdef HAVE_LIBUNWIND_X86_SUPPORT
+			pr_err("unwind: target platform=%s is not implemented\n", arch);
+#else
+			pr_err("unwind: target platform=%s is not supported\n", arch);
+#endif
+	}
+
 	register_local_unwind_libunwind_ops(thread);
 
 	return thread->unwind_libunwind_ops->prepare_access(thread);
diff --git a/tools/perf/util/unwind.h b/tools/perf/util/unwind.h
index 0122797..4de423c 100644
--- a/tools/perf/util/unwind.h
+++ b/tools/perf/util/unwind.h
@@ -22,11 +22,12 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
 /* libunwind specific */
 #ifdef HAVE_LIBUNWIND_SUPPORT
 int libunwind__arch_reg_id(int regnum);
-int unwind__prepare_access(struct thread *thread);
+int unwind__prepare_access(struct thread *thread, struct map *map);
 void unwind__flush_access(struct thread *thread);
 void unwind__finish_access(struct thread *thread);
 #else
-static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
+static inline int unwind__prepare_access(struct thread *thread __maybe_unused,
+					 struct map *map __maybe_unused)
 {
 	return 0;
 }
-- 
1.8.5.2