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Date: Wed, 13 Apr 2016 11:35:26 +0900
From: Masahiro Yamada <yamada.masahiro@...ionext.com>
To: Emese Revfy <re.emese@...il.com>
Cc: Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        pageexec@...email.hu, spender@...ecurity.net,
        kernel-hardening@...ts.openwall.com, Michal Marek <mmarek@...e.com>,
        Kees Cook <keescook@...omium.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>, fengguang.wu@...el.com,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        David Brown <david.brown@...aro.org>
Subject: Re: [PATCH v6 2/6] GCC plugin infrastructure

Hi Emese,


2016-04-08 6:13 GMT+09:00 Emese Revfy <re.emese@...il.com>:

> diff --git a/Makefile b/Makefile
> index 173437d..3af7b9e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -418,6 +418,8 @@ export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
>  export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
>  export KBUILD_ARFLAGS
>
> +export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
> +
>  # When compiling out-of-tree modules, put MODVERDIR in the module
>  # tree rather than in the kernel tree. The kernel tree might
>  # even be read-only.
> @@ -548,7 +550,7 @@ ifeq ($(KBUILD_EXTMOD),)
>  # in parallel
>  PHONY += scripts
>  scripts: scripts_basic include/config/auto.conf include/config/tristate.conf \
> -        asm-generic
> +        asm-generic gcc-plugins
>         $(Q)$(MAKE) $(build)=$(@)
>
>  # Objects we will link into vmlinux / subdirs we need to visit
> @@ -623,6 +625,15 @@ endif
>  # Tell gcc to never replace conditional load with a non-conditional one
>  KBUILD_CFLAGS  += $(call cc-option,--param=allow-store-data-races=0)
>
> +PHONY += gcc-plugins
> +gcc-plugins: scripts_basic
> +ifdef CONFIG_GCC_PLUGINS
> +       $(Q)$(MAKE) $(build)=scripts/gcc-plugins
> +endif
> +       @:
> +
> +include scripts/Makefile.gcc-plugins
> +
>  ifdef CONFIG_READABLE_ASM
>  # Disable optimizations that make assembler listings hard to read.
>  # reorder blocks reorders the control in the function
> @@ -949,6 +960,8 @@ endif
>
>  # The actual objects are generated when descending,
>  # make sure no implicit rule kicks in
> +$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;

I do not get your intention here.

It looks like you are trying to omit plugin flags for init/ directory.
(Actually this code is not working, though)

Then, you add plug the following lines to init/Makefile

+ccflags-y := $(GCC_PLUGINS_CFLAGS)
+asflags-y := $(GCC_PLUGINS_AFLAGS)






>  # Handle descending into subdirectories listed in $(vmlinux-dirs)
> @@ -1001,10 +1014,13 @@ prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
>
>  archprepare: archheaders archscripts prepare1 scripts_basic
>
> -prepare0: archprepare FORCE
> +prepare0: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +prepare0: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
> +prepare0: archprepare gcc-plugins FORCE
>         $(Q)$(MAKE) $(build)=.
>
>  # All the preparing..
> +prepare: KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
>  prepare: prepare0 prepare-objtool
>
>  ifdef CONFIG_STACK_VALIDATION
> @@ -1137,6 +1153,8 @@ all: modules
>  # using awk while concatenating to the final file.
>
>  PHONY += modules
> +modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
>         $(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
>         @$(kecho) '  Building modules, stage 2.';
> @@ -1257,7 +1275,7 @@ distclean: mrproper
>         @find $(srctree) $(RCS_FIND_IGNORE) \
>                 \( -name '*.orig' -o -name '*.rej' -o -name '*~' \
>                 -o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
> -               -o -name '.*.rej' -o -name '*%'  -o -name 'core' \) \
> +               -o -name '.*.rej' -o -name '*.so' -o -name '*%' -o -name 'core' \) \
>                 -type f -print | xargs rm -f
>
>
> @@ -1426,6 +1444,8 @@ PHONY += $(module-dirs) modules
>  $(module-dirs): crmodverdir $(objtree)/Module.symvers
>         $(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)
>
> +modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  modules: $(module-dirs)
>         @$(kecho) '  Building modules, stage 2.';
>         $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
> @@ -1567,10 +1587,14 @@ else
>          target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
>  endif
>
> +%.s: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +%.s: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  %.s: %.c prepare scripts FORCE
>         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
>  %.i: %.c prepare scripts FORCE
>         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
> +%.o: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +%.o: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  %.o: %.c prepare scripts FORCE
>         $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
>  %.lst: %.c prepare scripts FORCE
> @@ -1589,10 +1613,14 @@ endif
>         $(build)=$(build-dir)
>  # Make sure the latest headers are built for Documentation
>  Documentation/: headers_install
> +%/: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +%/: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  %/: prepare scripts FORCE
>         $(cmd_crmodverdir)
>         $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
>         $(build)=$(build-dir)
> +%.ko: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
> +%.ko: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
>  %.ko: prepare scripts FORCE
>         $(cmd_crmodverdir)
>         $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \


Why do you need to sprinkle "KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)"
here and there?


Unless I am missing something, I think the following should work.



diff --git a/Makefile b/Makefile
index 5d65f4b..f85420b 100644
--- a/Makefile
+++ b/Makefile
@@ -962,8 +962,6 @@ endif

 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
-$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-$(filter-out $(init-y),$(vmlinux-deps)): KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 $(sort $(vmlinux-deps)): $(vmlinux-dirs) ;

 # Handle descending into subdirectories listed in $(vmlinux-dirs)
@@ -1016,13 +1014,10 @@ prepare1: prepare2 $(version_h)
include/generated/utsrelease.h

 archprepare: archheaders archscripts prepare1 scripts_basic

-prepare0: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-prepare0: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 prepare0: archprepare gcc-plugins FORCE
        $(Q)$(MAKE) $(build)=.

 # All the preparing..
-prepare: KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 prepare: prepare0 prepare-objtool

 ifdef CONFIG_STACK_VALIDATION
@@ -1155,8 +1150,6 @@ all: modules
 # using awk while concatenating to the final file.

 PHONY += modules
-modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
        $(Q)$(AWK) '!x[$$0]++'
$(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtre
        @$(kecho) '  Building modules, stage 2.';
@@ -1446,8 +1439,6 @@ PHONY += $(module-dirs) modules
 $(module-dirs): crmodverdir $(objtree)/Module.symvers
        $(Q)$(MAKE) $(build)=$(patsubst _module_%,%,$@)

-modules: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-modules: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 modules: $(module-dirs)
        @$(kecho) '  Building modules, stage 2.';
        $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
@@ -1589,14 +1580,10 @@ else
         target-dir = $(if $(KBUILD_EXTMOD),$(dir $<),$(dir $@))
 endif

-%.s: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-%.s: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 %.s: %.c prepare scripts FORCE
        $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.i: %.c prepare scripts FORCE
        $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
-%.o: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-%.o: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 %.o: %.c prepare scripts FORCE
        $(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
 %.lst: %.c prepare scripts FORCE
@@ -1615,14 +1602,10 @@ endif
        $(build)=$(build-dir)
 # Make sure the latest headers are built for Documentation
 Documentation/: headers_install
-%/: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-%/: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 %/: prepare scripts FORCE
        $(cmd_crmodverdir)
        $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
        $(build)=$(build-dir)
-%.ko: KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
-%.ko: KBUILD_AFLAGS += $(GCC_PLUGINS_AFLAGS)
 %.ko: prepare scripts FORCE
        $(cmd_crmodverdir)
        $(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1)   \
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 25a70fb..34d6224 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -26,4 +26,6 @@ ifdef CONFIG_GCC_PLUGINS
     endif
   endif

+  KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS)
+
 endif






-- 
Best Regards
Masahiro Yamada

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