tools features: Don't check for libunwind devel files by default

Since 13e17c9ff49119aa ("perf build: Make libunwind opt-in rather than
opt-out"), so we shouldn't by default be testing for its availability at
build time in tools/build/features/test-all.c.

That test was designed to test the features we expect to be the most
common ones in most builds, so if we test build just that file, then we
assume the features there are present and will not test one by one.

Removing it from test-all.c gets rid of the first impediment for
test-all.c to build successfully:

  $ cat /tmp/build/perf-tools-next/feature/test-all.make.output
  In file included from test-all.c:62:
  test-libunwind.c:2:10: fatal error: libunwind.h: No such file or directory
      2 | #include <libunwind.h>
        |          ^~~~~~~~~~~~~
  compilation terminated.
  $

We then get to:

  $ cat /tmp/build/perf-tools-next/feature/test-all.make.output
  /usr/bin/ld: cannot find -lunwind-x86_64: No such file or directory
  /usr/bin/ld: cannot find -lunwind: No such file or directory
  collect2: error: ld returned 1 exit status
  $

So make all the logic related to setting CFLAGS, LDFLAGS, etc for
libunwind to be conditional on NO_LIBWUNWIND=1, which is now the
default, now we get a faster build:

  $ cat /tmp/build/perf-tools-next/feature/test-all.make.output
  $ ldd /tmp/build/perf-tools-next/feature/test-all.bin
  	linux-vdso.so.1 (0x00007fef04cde000)
  	libdw.so.1 => /lib64/libdw.so.1 (0x00007fef04a49000)
  	libpython3.12.so.1.0 => /lib64/libpython3.12.so.1.0 (0x00007fef04478000)
  	libm.so.6 => /lib64/libm.so.6 (0x00007fef04394000)
  	libtraceevent.so.1 => /lib64/libtraceevent.so.1 (0x00007fef0436c000)
  	libtracefs.so.1 => /lib64/libtracefs.so.1 (0x00007fef04345000)
  	libcrypto.so.3 => /lib64/libcrypto.so.3 (0x00007fef03e95000)
  	libz.so.1 => /lib64/libz.so.1 (0x00007fef03e72000)
  	libelf.so.1 => /lib64/libelf.so.1 (0x00007fef03e56000)
  	libnuma.so.1 => /lib64/libnuma.so.1 (0x00007fef03e48000)
  	libslang.so.2 => /lib64/libslang.so.2 (0x00007fef03b65000)
  	libperl.so.5.38 => /lib64/libperl.so.5.38 (0x00007fef037c6000)
  	libc.so.6 => /lib64/libc.so.6 (0x00007fef035d5000)
  	liblzma.so.5 => /lib64/liblzma.so.5 (0x00007fef035a0000)
  	libzstd.so.1 => /lib64/libzstd.so.1 (0x00007fef034e1000)
  	libbz2.so.1 => /lib64/libbz2.so.1 (0x00007fef034cd000)
  	/lib64/ld-linux-x86-64.so.2 (0x00007fef04ce0000)
  	libcrypt.so.2 => /lib64/libcrypt.so.2 (0x00007fef03495000)
  $

Fixes: 13e17c9ff49119aa ("perf build: Make libunwind opt-in rather than opt-out")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/Z09zTztD8X8qIWCX@x1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 49 insertions, 39 deletions

diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index 59ef3d7fe6a4..80ac297f8196 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -58,10 +58,6 @@
 # include "test-libelf-getshdrstrndx.c"
 #undef main
 
-#define main main_test_libunwind
-# include "test-libunwind.c"
-#undef main
-
 #define main main_test_libslang
 # include "test-libslang.c"
 #undef main
@@ -184,7 +180,6 @@ int main(int argc, char *argv[])
 	main_test_libelf_getphdrnum();
 	main_test_libelf_gelf_getnote();
 	main_test_libelf_getshdrstrndx();
-	main_test_libunwind();
 	main_test_libslang();
 	main_test_libbfd();
 	main_test_libbfd_buildid();
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 2916d59c88cd..0e4f6a860ae2 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -43,7 +43,9 @@ endif
 # Additional ARCH settings for ppc
 ifeq ($(SRCARCH),powerpc)
   CFLAGS += -I$(OUTPUT)arch/powerpc/include/generated
-  LIBUNWIND_LIBS := -lunwind -lunwind-ppc64
+  ifndef NO_LIBUNWIND
+    LIBUNWIND_LIBS := -lunwind -lunwind-ppc64
+  endif
 endif
 
 # Additional ARCH settings for x86
@@ -53,25 +55,35 @@ ifeq ($(SRCARCH),x86)
   ifeq (${IS_64_BIT}, 1)
     CFLAGS += -DHAVE_ARCH_X86_64_SUPPORT
     ARCH_INCLUDE = ../../arch/x86/lib/memcpy_64.S ../../arch/x86/lib/memset_64.S
-    LIBUNWIND_LIBS = -lunwind-x86_64 -lunwind -llzma
+    ifndef NO_LIBUNWIND
+      LIBUNWIND_LIBS = -lunwind-x86_64 -lunwind -llzma
+    endif
     $(call detected,CONFIG_X86_64)
   else
-    LIBUNWIND_LIBS = -lunwind-x86 -llzma -lunwind
+    ifndef NO_LIBUNWIND
+      LIBUNWIND_LIBS = -lunwind-x86 -llzma -lunwind
+    endif
   endif
 endif
 
 ifeq ($(SRCARCH),arm)
-  LIBUNWIND_LIBS = -lunwind -lunwind-arm
+  ifndef NO_LIBUNWIND
+    LIBUNWIND_LIBS = -lunwind -lunwind-arm
+  endif
 endif
 
 ifeq ($(SRCARCH),arm64)
   CFLAGS += -I$(OUTPUT)arch/arm64/include/generated
-  LIBUNWIND_LIBS = -lunwind -lunwind-aarch64
+  ifndef NO_LIBUNWIND
+    LIBUNWIND_LIBS = -lunwind -lunwind-aarch64
+  endif
 endif
 
 ifeq ($(SRCARCH),loongarch)
   CFLAGS += -I$(OUTPUT)arch/loongarch/include/generated
-  LIBUNWIND_LIBS = -lunwind -lunwind-loongarch64
+  ifndef NO_LIBUNWIND
+    LIBUNWIND_LIBS = -lunwind -lunwind-loongarch64
+  endif
 endif
 
 ifeq ($(ARCH),s390)
@@ -80,7 +92,9 @@ endif
 
 ifeq ($(ARCH),mips)
   CFLAGS += -I$(OUTPUT)arch/mips/include/generated
-  LIBUNWIND_LIBS = -lunwind -lunwind-mips
+  ifndef NO_LIBUNWIND
+    LIBUNWIND_LIBS = -lunwind -lunwind-mips
+  endif
 endif
 
 ifeq ($(ARCH),riscv)
@@ -121,16 +135,18 @@ ifdef LIBUNWIND_DIR
   $(foreach libunwind_arch,$(LIBUNWIND_ARCHS),$(call libunwind_arch_set_flags,$(libunwind_arch)))
 endif
 
-# Set per-feature check compilation flags
-FEATURE_CHECK_CFLAGS-libunwind = $(LIBUNWIND_CFLAGS)
-FEATURE_CHECK_LDFLAGS-libunwind = $(LIBUNWIND_LDFLAGS) $(LIBUNWIND_LIBS)
-FEATURE_CHECK_CFLAGS-libunwind-debug-frame = $(LIBUNWIND_CFLAGS)
-FEATURE_CHECK_LDFLAGS-libunwind-debug-frame = $(LIBUNWIND_LDFLAGS) $(LIBUNWIND_LIBS)
-
-FEATURE_CHECK_LDFLAGS-libunwind-arm += -lunwind -lunwind-arm
-FEATURE_CHECK_LDFLAGS-libunwind-aarch64 += -lunwind -lunwind-aarch64
-FEATURE_CHECK_LDFLAGS-libunwind-x86 += -lunwind -llzma -lunwind-x86
-FEATURE_CHECK_LDFLAGS-libunwind-x86_64 += -lunwind -llzma -lunwind-x86_64
+ifndef NO_LIBUNWIND
+  # Set per-feature check compilation flags
+  FEATURE_CHECK_CFLAGS-libunwind = $(LIBUNWIND_CFLAGS)
+  FEATURE_CHECK_LDFLAGS-libunwind = $(LIBUNWIND_LDFLAGS) $(LIBUNWIND_LIBS)
+  FEATURE_CHECK_CFLAGS-libunwind-debug-frame = $(LIBUNWIND_CFLAGS)
+  FEATURE_CHECK_LDFLAGS-libunwind-debug-frame = $(LIBUNWIND_LDFLAGS) $(LIBUNWIND_LIBS)
+  
+  FEATURE_CHECK_LDFLAGS-libunwind-arm += -lunwind -lunwind-arm
+  FEATURE_CHECK_LDFLAGS-libunwind-aarch64 += -lunwind -lunwind-aarch64
+  FEATURE_CHECK_LDFLAGS-libunwind-x86 += -lunwind -llzma -lunwind-x86
+  FEATURE_CHECK_LDFLAGS-libunwind-x86_64 += -lunwind -llzma -lunwind-x86_64
+endif
 
 FEATURE_CHECK_LDFLAGS-libcrypto = -lcrypto
 
@@ -734,26 +750,25 @@ ifeq ($(dwarf-post-unwind),1)
   $(call detected,CONFIG_DWARF_UNWIND)
 endif
 
-ifndef NO_LOCAL_LIBUNWIND
-  ifeq ($(SRCARCH),$(filter $(SRCARCH),arm arm64))
-    $(call feature_check,libunwind-debug-frame)
-    ifneq ($(feature-libunwind-debug-frame), 1)
-      $(warning No debug_frame support found in libunwind)
+ifndef NO_LIBUNWIND
+  ifndef NO_LOCAL_LIBUNWIND
+    ifeq ($(SRCARCH),$(filter $(SRCARCH),arm arm64))
+      $(call feature_check,libunwind-debug-frame)
+      ifneq ($(feature-libunwind-debug-frame), 1)
+        $(warning No debug_frame support found in libunwind)
+        CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
+      endif
+    else
+      # non-ARM has no dwarf_find_debug_frame() function:
       CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
     endif
-  else
-    # non-ARM has no dwarf_find_debug_frame() function:
-    CFLAGS += -DNO_LIBUNWIND_DEBUG_FRAME
+    EXTLIBS += $(LIBUNWIND_LIBS)
+    LDFLAGS += $(LIBUNWIND_LIBS)
+  endif
+  ifeq ($(findstring -static,${LDFLAGS}),-static)
+    # gcc -static links libgcc_eh which contans piece of libunwind
+    LIBUNWIND_LDFLAGS += -Wl,--allow-multiple-definition
   endif
-  EXTLIBS += $(LIBUNWIND_LIBS)
-  LDFLAGS += $(LIBUNWIND_LIBS)
-endif
-ifeq ($(findstring -static,${LDFLAGS}),-static)
-  # gcc -static links libgcc_eh which contans piece of libunwind
-  LIBUNWIND_LDFLAGS += -Wl,--allow-multiple-definition
-endif
-
-ifndef NO_LIBUNWIND
   CFLAGS  += -DHAVE_LIBUNWIND_SUPPORT
   CFLAGS  += $(LIBUNWIND_CFLAGS)
   LDFLAGS += $(LIBUNWIND_LDFLAGS)