[PATCH 15/16] perf tools: Setup default dwarf post unwinder

[Jiri Olsa <jolsa@redhat.com>]

Factor NO_LIBDW_DWARF_UNWIND makefile variable and code
that selects default DWARf post unwinder based on detected
features (libdw and libunwind support)

If both are detected the libunwind is selected as default.
Simple 'make' will try to add:
  - libunwind unwinder if present
  - libdw unwinder if present
  - disable dwarf unwind if non of libunwind and libdw
    libraries are present

Examples:
  - compile in libdw unwinder if present:
    $ make NO_LIBUNWIND=1

  - compile in libdw (with libdw installation directory) unwinder if present:
    $ make LIBDW_DIR=/opt/elfutils/ NO_LIBUNWIND=1

  - disable post dwarf unwind completely:
    $ make NO_LIBUNWIND=1 NO_LIBDW_DWARF_UNWIND=1

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jean Pihet <jean.pihet@linaro.org>
---
 tools/perf/Makefile.perf     |  5 +---
 tools/perf/arch/x86/Makefile |  6 +++--
 tools/perf/config/Makefile   | 59 ++++++++++++++++++++++++++++++++------------
 3 files changed, 48 insertions(+), 22 deletions(-)

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 9b9f9d2..d76c1f1 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -59,9 +59,6 @@ include config/utilities.mak
 # Define NO_LIBDW_DWARF_UNWIND if you do not want libdw support
 # for dwarf backtrace post unwind.
 
-# temporarily disabled
-NO_LIBDW_DWARF_UNWIND := 1
-
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(shell pwd)))
 srctree := $(patsubst %/,%,$(dir $(srctree)))
@@ -413,7 +410,7 @@ endif
 LIB_OBJS += $(OUTPUT)tests/code-reading.o
 LIB_OBJS += $(OUTPUT)tests/sample-parsing.o
 LIB_OBJS += $(OUTPUT)tests/parse-no-sample-id-all.o
-ifndef NO_LIBUNWIND
+ifndef NO_DWARF_UNWIND
 ifeq ($(ARCH),x86)
 LIB_OBJS += $(OUTPUT)tests/dwarf-unwind.o
 endif
diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile
index 37c4652..1641542 100644
--- a/tools/perf/arch/x86/Makefile
+++ b/tools/perf/arch/x86/Makefile
@@ -4,12 +4,14 @@ LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
 endif
 ifndef NO_LIBUNWIND
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/unwind-libunwind.o
-LIB_OBJS += $(OUTPUT)arch/$(ARCH)/tests/regs_load.o
-LIB_OBJS += $(OUTPUT)arch/$(ARCH)/tests/dwarf-unwind.o
 endif
 ifndef NO_LIBDW_DWARF_UNWIND
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/unwind-libdw.o
 endif
+ifndef NO_DWARF_UNWIND
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/tests/regs_load.o
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/tests/dwarf-unwind.o
+endif
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o
 LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/tsc.o
 LIB_H += arch/$(ARCH)/util/tsc.h
diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
index bd6096a..8bcf143 100644
--- a/tools/perf/config/Makefile
+++ b/tools/perf/config/Makefile
@@ -295,6 +295,12 @@ else
       msg := $(error No gnu/libc-version.h found, please install glibc-dev[el]/glibc-static);
     endif
   else
+    ifndef NO_LIBDW_DWARF_UNWIND
+      ifneq ($(feature-libdw-dwarf-unwind),1)
+        NO_LIBDW_DWARF_UNWIND := 1
+        msg := $(warning No libdw dwarf unwind found, Please install elfutils-devel/libdw-dev >= 0.158.);
+      endif
+    endif
     ifneq ($(feature-dwarf), 1)
       msg := $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.138, disables dwarf support. Please install new elfutils-devel/libdw-dev);
       NO_DWARF := 1
@@ -330,25 +336,46 @@ endif # NO_LIBELF
 
 ifndef NO_LIBUNWIND
   ifneq ($(feature-libunwind), 1)
-    msg := $(warning No libunwind found, disabling post unwind support. Please install libunwind-dev[el] >= 1.1);
+    msg := $(warning No libunwind found. Please install libunwind-dev[el] >= 1.1);
     NO_LIBUNWIND := 1
-  else
-    ifeq ($(ARCH),arm)
-      $(call feature_check,libunwind-debug-frame)
-      ifneq ($(feature-libunwind-debug-frame), 1)
-        msg := $(warning No debug_frame support found in libunwind);
-        CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
-      endif
-    else
-      # non-ARM has no dwarf_find_debug_frame() function:
+  endif
+endif
+
+dwarf-post-unwind := 1
+# setup DWARF post unwinder
+ifdef NO_LIBUNWIND
+  ifdef NO_LIBDW_DWARF_UNWIND
+    msg := $(warning Disabling post unwind, no support found.);
+    dwarf-post-unwind := 0
+  endif
+else
+  # Enable libunwind support by default.
+  ifndef NO_LIBDW_DWARF_UNWIND
+    NO_LIBDW_DWARF_UNWIND := 1
+  endif
+endif
+
+ifeq ($(dwarf-post-unwind),1)
+  CFLAGS += -DHAVE_DWARF_UNWIND_SUPPORT
+else
+  NO_DWARF_UNWIND := 1
+endif
+
+ifndef NO_LIBUNWIND
+  ifeq ($(ARCH),arm)
+    $(call feature_check,libunwind-debug-frame)
+    ifneq ($(feature-libunwind-debug-frame), 1)
+      msg := $(warning No debug_frame support found in libunwind);
       CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
     endif
-
-    CFLAGS += -DHAVE_DWARF_UNWIND_SUPPORT -DHAVE_LIBUNWIND_SUPPORT
-    EXTLIBS += $(LIBUNWIND_LIBS)
-    CFLAGS += $(LIBUNWIND_CFLAGS)
-    LDFLAGS += $(LIBUNWIND_LDFLAGS)
-  endif # ifneq ($(feature-libunwind), 1)
+  else
+    # non-ARM has no dwarf_find_debug_frame() function:
+    CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
+  endif
+  CFLAGS  += -DHAVE_LIBUNWIND_SUPPORT
+  EXTLIBS += $(LIBUNWIND_LIBS)
+  CFLAGS  += $(LIBUNWIND_CFLAGS)
+  LDFLAGS += $(LIBUNWIND_LDFLAGS)
 endif
 
 ifndef NO_LIBAUDIT
-- 
1.8.3.1