[tip:core/urgent] objtool: Query pkg-config for libelf location

[tip-bot for Rolf Eike Beer]

Commit-ID:  056d28d135bca0b1d0908990338e00e9dadaf057
Gitweb:     https://git.kernel.org/tip/056d28d135bca0b1d0908990338e00e9dadaf057
Author:     Rolf Eike Beer <eb@xxxxxxxxx>
AuthorDate: Tue, 26 Mar 2019 12:48:39 -0500
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 28 Mar 2019 13:32:01 +0100

objtool: Query pkg-config for libelf location

If it is not in the default location, compilation fails at several points.

Signed-off-by: Rolf Eike Beer <eb@xxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/91a25e992566a7968fedc89ec80e7f4c83ad0548.1553622500.git.jpoimboe@xxxxxxxxxx

---
 Makefile               | 4 +++-
 tools/objtool/Makefile | 7 +++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index c0a34064c574..eef3d3f87c3b 100644
--- a/Makefile
+++ b/Makefile
@@ -950,9 +950,11 @@ mod_sign_cmd = true
 endif
 export mod_sign_cmd
 
+HOST_LIBELF_LIBS = $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+
 ifdef CONFIG_STACK_VALIDATION
   has_libelf := $(call try-run,\
-		echo "int main() {}" | $(HOSTCC) -xc -o /dev/null -lelf -,1,0)
+		echo "int main() {}" | $(HOSTCC) -xc -o /dev/null $(HOST_LIBELF_LIBS) -,1,0)
   ifeq ($(has_libelf),1)
     objtool_target := tools/objtool FORCE
   else
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index c9d038f91af6..53f8be0f4a1f 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -25,14 +25,17 @@ LIBSUBCMD		= $(LIBSUBCMD_OUTPUT)libsubcmd.a
 OBJTOOL    := $(OUTPUT)objtool
 OBJTOOL_IN := $(OBJTOOL)-in.o
 
+LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
+LIBELF_LIBS  := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
+
 all: $(OBJTOOL)
 
 INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
 	    -I$(srctree)/tools/objtool/arch/$(ARCH)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
-CFLAGS   += -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES)
-LDFLAGS  += -lelf $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
+CFLAGS   += -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
+LDFLAGS  += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
 
 # Allow old libelf to be used:
 elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)