kbuild: move host .so build rules to scripts/gcc-plugins/Makefile

The host shared library rules are currently implemented in
scripts/Makefile.host, but actually GCC-plugin is the only user of
them. (The VDSO .so files are built for the target by different
build rules) Hence, they do not need to be treewide available.

Move all the relevant build rules to scripts/gcc-plugins/Makefile.

I also optimized the build steps so *.so is directly built from .c
because every upstream plugin is compiled from a single source file.

I am still keeping the multi-file plugin support, which Kees Cook
mentioned might be needed by out-of-tree plugins.
(https://lkml.org/lkml/2019/1/11/1107)

If the plugin, foo.so, is compiled from two files foo.c and foo2.c,
then you can do like follows:

  foo-objs := foo.o foo2.o

Single-file plugins do not need the *-objs notation.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 246426fa12824b8ec7fa39a8247feba83ce54805..d54adf0dcf39d67b76368b9f7027c6c0fc7da08f 100644 (file)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -45,8 +45,8 @@ include $(kbuild-file)
 
 include scripts/Makefile.lib
 
-# Do not include host rules unless needed
-ifneq ($(hostprogs)$(hostcxxlibs-y)$(hostcxxlibs-m),)
+# Do not include hostprogs rules unless needed
+ifneq ($(hostprogs),)
 include scripts/Makefile.host
 endif
 

diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index e2c76122319d75d37a7980fda543455249cc4db3..3cdf31218198b1c278c84f6765105391be4bb67e 100644 (file)
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -29,8 +29,7 @@ subdir-ymn    := $(addprefix $(obj)/,$(subdir-ymn))
 
 __clean-files  := $(extra-y) $(extra-m) $(extra-)       \
                   $(always) $(always-y) $(always-m) $(always-) $(targets) $(clean-files)   \
-                  $(hostprogs) $(hostprogs-y) $(hostprogs-m) $(hostprogs-) $(userprogs) \
-                  $(hostcxxlibs-y) $(hostcxxlibs-m)
+                  $(hostprogs) $(hostprogs-y) $(hostprogs-m) $(hostprogs-) $(userprogs)
 
 __clean-files   := $(filter-out $(no-clean-files), $(__clean-files))
 

diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index c8a4a033dc3e9b2cd5fa71c62862c45d8ed8830f..687ca3f309e9b9762e7f3baca0ffe4369a265767 100644 (file)
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -39,7 +39,6 @@ $(obj)/%.tab.c $(obj)/%.tab.h: $(src)/%.y FORCE
 # They are linked as C++ code to the executable qconf
 
 __hostprogs := $(sort $(hostprogs))
-host-cxxshlib := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
 
 # C code
 # Executables compiled from a single .c file
@@ -61,16 +60,11 @@ host-cxxmulti       := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
 # C++ Object (.o) files compiled from .cc files
 host-cxxobjs   := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
 
-# Object (.o) files used by the shared libaries
-host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
-
 host-csingle   := $(addprefix $(obj)/,$(host-csingle))
 host-cmulti    := $(addprefix $(obj)/,$(host-cmulti))
 host-cobjs     := $(addprefix $(obj)/,$(host-cobjs))
 host-cxxmulti  := $(addprefix $(obj)/,$(host-cxxmulti))
 host-cxxobjs   := $(addprefix $(obj)/,$(host-cxxobjs))
-host-cxxshlib  := $(addprefix $(obj)/,$(host-cxxshlib))
-host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs))
 
 #####
 # Handle options to gcc. Support building with separate output directory
@@ -136,25 +130,5 @@ quiet_cmd_host-cxxobjs     = HOSTCXX $@
 $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
        $(call if_changed_dep,host-cxxobjs)
 
-# Compile .c file, create position independent .o file
-# Note that plugin capable gcc versions can be either C or C++ based
-# therefore plugin source files have to be compilable in both C and C++ mode.
-# This is why a C++ compiler is invoked on a .c file.
-# host-cxxshobjs -> .o
-quiet_cmd_host-cxxshobjs       = HOSTCXX -fPIC $@
-      cmd_host-cxxshobjs       = $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $<
-$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
-       $(call if_changed_dep,host-cxxshobjs)
-
-# Link a shared library, based on position independent .o files
-# *.o -> .so shared library (host-cxxshlib)
-quiet_cmd_host-cxxshlib        = HOSTLLD -shared $@
-      cmd_host-cxxshlib        = $(HOSTCXX) $(KBUILD_HOSTLDFLAGS) -shared -o $@ \
-                         $(addprefix $(obj)/, $($(target-stem)-objs)) \
-                         $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
-$(host-cxxshlib): FORCE
-       $(call if_changed,host-cxxshlib)
-$(call multi_depend, $(host-cxxshlib), .so, -objs)
-
-targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
-          $(host-cxxmulti) $(host-cxxobjs) $(host-cxxshlib) $(host-cxxshobjs)
+targets += $(host-csingle) $(host-cmulti) $(host-cobjs) \
+          $(host-cxxmulti) $(host-cxxobjs)

diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile
index 4014ba7e2fbd2e4f1254bea21312c1294f5ab6d3..d66949bfeba45cbfa285264e4a842acd7ab06907 100644 (file)
--- a/scripts/gcc-plugins/Makefile
+++ b/scripts/gcc-plugins/Makefile
@@ -1,22 +1,61 @@
 # SPDX-License-Identifier: GPL-2.0
-GCC_PLUGINS_DIR := $(shell $(CC) -print-file-name=plugin)
 
-HOST_EXTRACXXFLAGS += -I$(GCC_PLUGINS_DIR)/include -I$(src) -std=gnu++98 -fno-rtti
-HOST_EXTRACXXFLAGS += -fno-exceptions -fasynchronous-unwind-tables -ggdb
-HOST_EXTRACXXFLAGS += -Wno-narrowing -Wno-unused-variable -Wno-c++11-compat
-HOST_EXTRACXXFLAGS += -Wno-format-diag
-
-$(obj)/randomize_layout_plugin.o: $(objtree)/$(obj)/randomize_layout_seed.h
+$(obj)/randomize_layout_plugin.so: $(objtree)/$(obj)/randomize_layout_seed.h
 quiet_cmd_create_randomize_layout_seed = GENSEED $@
 cmd_create_randomize_layout_seed = \
   $(CONFIG_SHELL) $(srctree)/$(src)/gen-random-seed.sh $@ $(objtree)/include/generated/randomize_layout_hash.h
 $(objtree)/$(obj)/randomize_layout_seed.h: FORCE
        $(call if_changed,create_randomize_layout_seed)
-targets = randomize_layout_seed.h randomize_layout_hash.h
+targets += randomize_layout_seed.h randomize_layout_hash.h
+
+# Build rules for plugins
+#
+# No extra code is needed for single-file plugins.
+# For multi-file plugins, use *-objs syntax to list the objects.
+#
+# If the plugin foo.so is compiled from foo.c and foo2.c, you can do:
+#
+# foo-objs := foo.o foo2.o
+
+always-y += $(GCC_PLUGIN)
 
-hostcxxlibs-y := $(GCC_PLUGIN)
-always-y := $(hostcxxlibs-y)
+GCC_PLUGINS_DIR = $(shell $(CC) -print-file-name=plugin)
 
-$(foreach p,$(hostcxxlibs-y:%.so=%),$(eval $(p)-objs := $(p).o))
+plugin_cxxflags        = -Wp,-MMD,$(depfile) $(KBUILD_HOSTCXXFLAGS) -fPIC \
+                  -I $(GCC_PLUGINS_DIR)/include -I $(obj) -std=gnu++98 \
+                  -fno-rtti -fno-exceptions -fasynchronous-unwind-tables \
+                  -ggdb -Wno-narrowing -Wno-unused-variable -Wno-c++11-compat \
+                  -Wno-format-diag
 
+plugin_ldflags = -shared
+
+plugin-single  := $(foreach m, $(GCC_PLUGIN), $(if $($(m:%.so=%-objs)),,$(m)))
+plugin-multi   := $(filter-out $(plugin-single), $(GCC_PLUGIN))
+plugin-objs    := $(sort $(foreach m, $(plugin-multi), $($(m:%.so=%-objs))))
+
+targets += $(plugin-single) $(plugin-multi) $(plugin-objs)
 clean-files += *.so
+
+plugin-single  := $(addprefix $(obj)/, $(plugin-single))
+plugin-multi   := $(addprefix $(obj)/, $(plugin-multi))
+plugin-objs    := $(addprefix $(obj)/, $(plugin-objs))
+
+quiet_cmd_plugin_cxx_so_c = HOSTCXX $@
+      cmd_plugin_cxx_so_c = $(HOSTCXX) $(plugin_cxxflags) $(plugin_ldflags) -o $@ $<
+
+$(plugin-single): $(obj)/%.so: $(src)/%.c FORCE
+       $(call if_changed_dep,plugin_cxx_so_c)
+
+quiet_cmd_plugin_ld_so_o = HOSTLD  $@
+      cmd_plugin_ld_so_o = $(HOSTCXX) $(plugin_ldflags) -o $@ \
+                          $(addprefix $(obj)/, $($(target-stem)-objs))
+
+$(plugin-multi): FORCE
+       $(call if_changed,plugin_ld_so_o)
+$(foreach m, $(notdir $(plugin-multi)), $(eval $(obj)/$m: $(addprefix $(obj)/, $($(m:%.so=%-objs)))))
+
+quiet_cmd_plugin_cxx_o_c = HOSTCXX $@
+      cmd_plugin_cxx_o_c = $(HOSTCXX) $(plugin_cxxflags) -c -o $@ $<
+
+$(plugin-objs): $(obj)/%.o: $(src)/%.c FORCE
+       $(call if_changed_dep,plugin_cxx_o_c)