[PATCH] perf tools: Fix dynamic libbpf link

[Jiri Olsa]

Justin reported broken build with LIBBPF_DYNAMIC=1.

When linking libbpf dynamically we need to use perf's
hashmap object, because it's not exported in libbpf.so
(only in libbpf.a).

Following build is now passing:

  $ make LIBBPF_DYNAMIC=1
    BUILD:   Doing 'make -j8' parallel build
    ...
  $ ldd perf | grep libbpf
        libbpf.so.0 => /lib64/libbpf.so.0 (0x00007fa7630db000)

Fixes: eee19501926d ("perf tools: Grab a copy of libbpf's hashmap")
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Reported-by: Justin M. Forbes <jforbes@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 tools/perf/Makefile.config | 1 +
 tools/perf/util/Build      | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7b195e16040e..dacd16874d3d 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -546,6 +546,7 @@ ifndef NO_LIBELF
       ifdef LIBBPF_DYNAMIC
         ifeq ($(feature-libbpf), 1)
           EXTLIBS += -lbpf
+          $(call detected,CONFIG_LIBBPF_DYNAMIC)
         else
           dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);
         endif
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index e27a551acd3a..95e15d1035ab 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -145,7 +145,14 @@ perf-$(CONFIG_LIBELF) += symbol-elf.o
 perf-$(CONFIG_LIBELF) += probe-file.o
 perf-$(CONFIG_LIBELF) += probe-event.o
 
+ifdef CONFIG_LIBBPF_DYNAMIC
+  hashmap := 1
+endif
 ifndef CONFIG_LIBBPF
+  hashmap := 1
+endif
+
+ifdef hashmap
 perf-y += hashmap.o
 endif
 
-- 
2.31.1