[PATCH v5 2/5] perf tools: Show warnings for unsupported cross-platform unwind

[He Kuang]

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.

Common functions which will be used by both local unwind and remote
unwind are separated into new file 'unwind-libunwind_common.c'.

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
 tools/perf/arch/common.c                  |  2 +-
 tools/perf/arch/common.h                  |  1 +
 tools/perf/config/Makefile                |  5 +++++
 tools/perf/util/Build                     |  1 +
 tools/perf/util/thread.c                  |  2 ++
 tools/perf/util/unwind-libunwind_common.c | 34 +++++++++++++++++++++++++++++++
 tools/perf/util/unwind.h                  |  5 +++++
 7 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/util/unwind-libunwind_common.c

diff --git a/tools/perf/arch/common.c b/tools/perf/arch/common.c
index e83c8ce..fa090a9 100644
--- a/tools/perf/arch/common.c
+++ b/tools/perf/arch/common.c
@@ -102,7 +102,7 @@ static int lookup_triplets(const char *const *triplets, const char *name)
  * Return architecture name in a normalized form.
  * The conversion logic comes from the Makefile.
  */
-static const char *normalize_arch(char *arch)
+const char *normalize_arch(char *arch)
 {
 	if (!strcmp(arch, "x86_64"))
 		return "x86";
diff --git a/tools/perf/arch/common.h b/tools/perf/arch/common.h
index 7529cfb..6b01c73 100644
--- a/tools/perf/arch/common.h
+++ b/tools/perf/arch/common.h
@@ -6,5 +6,6 @@
 extern const char *objdump_path;
 
 int perf_env__lookup_objdump(struct perf_env *env);
+const char *normalize_arch(char *arch);
 
 #endif /* ARCH_PERF_COMMON_H */
diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index 6f9f566..c9e1625 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -354,6 +354,11 @@ ifeq ($(ARCH),powerpc)
 endif
 
 ifndef NO_LIBUNWIND
+  ifeq ($(feature-libunwind-x86), 1)
+    $(call detected,CONFIG_LIBUNWIND_X86)
+    CFLAGS += -DHAVE_LIBUNWIND_X86_SUPPORT
+  endif
+
   ifneq ($(feature-libunwind), 1)
     msg := $(warning No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR);
     NO_LIBUNWIND := 1
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 8c6c8a0..25c31fb 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -100,6 +100,7 @@ libperf-$(CONFIG_DWARF) += dwarf-aux.o
 
 libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
 libperf-$(CONFIG_LIBUNWIND)          += unwind-libunwind.o
+libperf-$(CONFIG_LIBUNWIND)          += unwind-libunwind_common.o
 
 libperf-$(CONFIG_LIBBABELTRACE) += data-convert-bt.o
 
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 45fcb71..3043113 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -205,6 +205,8 @@ 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__get_arch(thread, map);
 }
 
 static int thread__clone_map_groups(struct thread *thread,
diff --git a/tools/perf/util/unwind-libunwind_common.c b/tools/perf/util/unwind-libunwind_common.c
new file mode 100644
index 0000000..3946c99
--- /dev/null
+++ b/tools/perf/util/unwind-libunwind_common.c
@@ -0,0 +1,34 @@
+#include "thread.h"
+#include "session.h"
+#include "unwind.h"
+#include "symbol.h"
+#include "debug.h"
+#include "arch/common.h"
+
+void unwind__get_arch(struct thread *thread, struct map *map)
+{
+	const char *arch;
+	enum dso_type dso_type;
+
+	if (!thread->mg->machine->env)
+		return;
+
+	dso_type = dso__type(map->dso, thread->mg->machine);
+	if (dso_type == DSO__TYPE_UNKNOWN)
+		return;
+
+	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
+	}
+}
diff --git a/tools/perf/util/unwind.h b/tools/perf/util/unwind.h
index 12790cf..889d630 100644
--- a/tools/perf/util/unwind.h
+++ b/tools/perf/util/unwind.h
@@ -24,6 +24,7 @@ int libunwind__arch_reg_id(int regnum);
 int unwind__prepare_access(struct thread *thread);
 void unwind__flush_access(struct thread *thread);
 void unwind__finish_access(struct thread *thread);
+void unwind__get_arch(struct thread *thread, struct map *map);
 #else
 static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
 {
@@ -32,6 +33,8 @@ static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
 
 static inline void unwind__flush_access(struct thread *thread __maybe_unused) {}
 static inline void unwind__finish_access(struct thread *thread __maybe_unused) {}
+static inline void unwind__get_arch(struct thread *thread __maybe_unused,
+				    struct map *map __maybe_unused) {}
 #endif
 #else
 static inline int
@@ -51,5 +54,7 @@ static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
 
 static inline void unwind__flush_access(struct thread *thread __maybe_unused) {}
 static inline void unwind__finish_access(struct thread *thread __maybe_unused) {}
+static inline void unwind__get_arch(struct thread *thread __maybe_unused,
+				    struct map *map __maybe_unused) {}
 #endif /* HAVE_DWARF_UNWIND_SUPPORT */
 #endif /* __UNWIND_H */
-- 
1.8.5.2