[PATCH 1/3] perf tools: Allow to specify libbpf install directory

[Jiri Olsa <jolsa@xxxxxxxxxx>]

Adding LIBBPF_DIR compile variable to allow linking with
libbpf installed into specific directory:

  $ make -C tools/lib/bpf/ prefix=/tmp/libbpf/ install_lib install_headers
  $ make -C tools/perf/ LIBBPF_DYNAMIC=1 LIBBPF_DIR=/tmp/libbpf/

It might be needed to clean build tree first because features
framework does not detect the change properly:

  $ make -C tools/build/feature clean
  $ make -C tools/perf/ clean

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/Makefile.config | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index c90f4146e5a2..eb9d9b70b7d3 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -22,6 +22,14 @@ include $(srctree)/tools/scripts/Makefile.arch
 
 $(call detected_var,SRCARCH)
 
+ifndef lib
+  ifeq ($(SRCARCH)$(IS_64_BIT), x861)
+    lib = lib64
+  else
+    lib = lib
+  endif
+endif # lib
+
 NO_PERF_REGS := 1
 NO_SYSCALL_TABLE := 1
 
@@ -484,11 +492,22 @@ ifndef NO_LIBELF
       CFLAGS += -DHAVE_LIBBPF_SUPPORT
       $(call detected,CONFIG_LIBBPF)
 
+      # for linking with debug library run:
+      # make DEBUG=1 LIBBPF_DIR=/opt/libbpf
+      ifdef LIBBPF_DIR
+        LIBBPF_CFLAGS  := -I$(LIBBPF_DIR)/include
+        LIBBPF_LDFLAGS := -L$(LIBBPF_DIR)/$(lib)
+        FEATURE_CHECK_CFLAGS-libbpf  := $(LIBBPF_CFLAGS)
+        FEATURE_CHECK_LDFLAGS-libbpf := $(LIBBPF_LDFLAGS)
+      endif
+
       # detecting libbpf without LIBBPF_DYNAMIC, so make VF=1 shows libbpf detection status
       $(call feature_check,libbpf)
       ifdef LIBBPF_DYNAMIC
         ifeq ($(feature-libbpf), 1)
           EXTLIBS += -lbpf
+          CFLAGS  += $(LIBBPF_CFLAGS)
+          LDFLAGS += $(LIBBPF_LDFLAGS)
         else
           dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);
         endif
@@ -1037,13 +1056,6 @@ else
 sysconfdir = $(prefix)/etc
 ETC_PERFCONFIG = etc/perfconfig
 endif
-ifndef lib
-ifeq ($(SRCARCH)$(IS_64_BIT), x861)
-lib = lib64
-else
-lib = lib
-endif
-endif # lib
 libdir = $(prefix)/$(lib)
 
 # Shell quote (do not use $(call) to accommodate ancient setups);
@@ -1108,6 +1120,7 @@ ifeq ($(VF),1)
   $(call print_var,LIBUNWIND_DIR)
   $(call print_var,LIBDW_DIR)
   $(call print_var,JDIR)
+  $(call print_var,LIBBPF_DIR)
 
   ifeq ($(dwarf-post-unwind),1)
     $(call feature_print_text,"DWARF post unwind library", $(dwarf-post-unwind-text))
-- 
2.21.0