selftests/bpf: Support dynamically linking LLVM if static is not avai…

…lable Since 67ab80a ("selftests/bpf: Prefer static linking for LLVM libraries"), only statically linking test_progs is supported. However, some distros only provide a dynamically linkable LLVM. This commit adds a fallback for dynamically linking LLVM if static linking is not available. If both options are available, static linking is chosen. Signed-off-by: Daniel Xu <[email protected]> Signed-off-by: Andrii Nakryiko <[email protected]> Tested-by: Eduard Zingerman <[email protected]> Acked-by: Yonghong Song <[email protected]> Link: https://lore.kernel.org/bpf/872b64e93de9a6cd6a7a10e6a5c5e7893704f743.1738276344.git.dxu@dxuuu.xyz
kernel-patches · Feb 6, 2025 · 2a9d30f · 2a9d30f
1 parent 12befeb
commit 2a9d30f
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
@@ -184,9 +184,14 @@ ifeq ($(feature-llvm),1)
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
   # both llvm-config and lib.mk add -D_GNU_SOURCE, which ends up as conflict
   LLVM_CFLAGS  += $(filter-out -D_GNU_SOURCE,$(shell $(LLVM_CONFIG) --cflags))
-  LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --libs $(LLVM_CONFIG_LIB_COMPONENTS))
-  LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
-  LLVM_LDLIBS  += -lstdc++
+  # Prefer linking statically if it's available, otherwise fallback to shared
+  ifeq ($(shell $(LLVM_CONFIG) --link-static --libs &> /dev/null && echo static),static)
+    LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+    LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-static --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
+    LLVM_LDLIBS  += -lstdc++
+  else
+    LLVM_LDLIBS  += $(shell $(LLVM_CONFIG) --link-shared --libs $(LLVM_CONFIG_LIB_COMPONENTS))
+  endif
   LLVM_LDFLAGS += $(shell $(LLVM_CONFIG) --ldflags)
 endif