objtool: Install libsubcmd in build

Including from tools/lib can create inadvertent dependencies. Install
libsubcmd in the objtool build and then include the headers from
there.
Signed-off-by: NIan Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230126190606.40739-2-irogers@google.comSigned-off-by: NJosh Poimboeuf <jpoimboe@kernel.org>

tools/objtool/.gitignore

@@ -2,3 +2,4 @@
 arch/x86/lib/inat-tables.c
 /objtool
 fixdep
+libsubcmd/

tools/objtool/Build

@@ -16,8 +16,6 @@ objtool-y += libctype.o
 objtool-y += str_error_r.o
 objtool-y += librbtree.o
 
-CFLAGS += -I$(srctree)/tools/lib
-
 $(OUTPUT)libstring.o: ../lib/string.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)

tools/objtool/Makefile

@@ -12,9 +12,13 @@ srctree := $(patsubst %/,%,$(dir $(CURDIR)))
 srctree := $(patsubst %/,%,$(dir $(srctree)))
 endif
 
-SUBCMD_SRCDIR		= $(srctree)/tools/lib/subcmd/
-LIBSUBCMD_OUTPUT	= $(or $(OUTPUT),$(CURDIR)/)
-LIBSUBCMD		= $(LIBSUBCMD_OUTPUT)libsubcmd.a
+LIBSUBCMD_DIR = $(srctree)/tools/lib/subcmd/
+ifneq ($(OUTPUT),)
+  LIBSUBCMD_OUTPUT = $(abspath $(OUTPUT))/libsubcmd
+else
+  LIBSUBCMD_OUTPUT = $(CURDIR)/libsubcmd
+endif
+LIBSUBCMD = $(LIBSUBCMD_OUTPUT)/libsubcmd.a
 
 OBJTOOL    := $(OUTPUT)objtool
 OBJTOOL_IN := $(OBJTOOL)-in.o
@@ -28,7 +32,8 @@ INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
 	    -I$(srctree)/tools/arch/$(SRCARCH)/include	\
 	    -I$(srctree)/tools/objtool/include \
-	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include
+	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
+	    -I$(LIBSUBCMD_OUTPUT)/include
 WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
 CFLAGS   := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
 LDFLAGS  += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
@@ -38,6 +43,7 @@ elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E -
 CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
 
 AWK = awk
+MKDIR = mkdir
 
 BUILD_ORC := n
 
@@ -57,13 +63,22 @@ $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
 	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
 
 
-$(LIBSUBCMD): fixdep FORCE
-	$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
+$(LIBSUBCMD_OUTPUT):
+	@$(MKDIR) -p $@
+
+$(LIBSUBCMD): fixdep $(LIBSUBCMD_OUTPUT) FORCE
+	@$(MAKE) -C $(LIBSUBCMD_DIR) O=$(LIBSUBCMD_OUTPUT) \
+		DESTDIR=$(LIBSUBCMD_OUTPUT) prefix= subdir= \
+		$@ install_headers
+
+$(LIBSUBCMD)-clean:
+	$(call QUIET_CLEAN, libsubcmd)
+	$(Q)$(RM) -r -- $(LIBSUBCMD_OUTPUT)
 
-clean:
+clean: $(LIBSUBCMD)-clean
 	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
 	$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
-	$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep $(LIBSUBCMD)
+	$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep
 
 FORCE: