Commit 596b0474 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: preprocess module linker script 

There was a request to preprocess the module linker script like we
do for the vmlinux one. (https://lkml.org/lkml/2020/8/21/512

)

The difference between vmlinux.lds and module.lds is that the latter
is needed for external module builds, thus must be cleaned up by
'make mrproper' instead of 'make clean'. Also, it must be created
by 'make modules_prepare'.

You cannot put it in arch/$(SRCARCH)/kernel/, which is cleaned up by
'make clean'. I moved arch/$(SRCARCH)/kernel/module.lds to
arch/$(SRCARCH)/include/asm/module.lds.h, which is included from
scripts/module.lds.S.

scripts/module.lds is fine because 'make clean' keeps all the
build artifacts under scripts/.

You can add arch-specific sections in <asm/module.lds.h>.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Tested-by: default avatarJessica Yu <jeyu@kernel.org>
Acked-by: default avatarWill Deacon <will@kernel.org>
Acked-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarJessica Yu <jeyu@kernel.org>
parent 887af6d7

Makefile

+6 −4
Original line number Diff line number Diff line
@@ -505,7 +505,6 @@ KBUILD_CFLAGS_KERNEL := 
KBUILD_AFLAGS_MODULE  := -DMODULE

KBUILD_CFLAGS_MODULE  := -DMODULE

KBUILD_LDFLAGS_MODULE :=

export KBUILD_LDS_MODULE := $(srctree)/scripts/module-common.lds

KBUILD_LDFLAGS :=

CLANG_FLAGS :=
@@ -1395,7 +1394,7 @@ endif 
# using awk while concatenating to the final file.



PHONY += modules

modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check

modules: $(if $(KBUILD_BUILTIN),vmlinux) modules_check modules_prepare

	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost



PHONY += modules_check
@@ -1412,6 +1411,7 @@ targets += modules.order 
# Target to prepare building external modules

PHONY += modules_prepare

modules_prepare: prepare

	$(Q)$(MAKE) $(build)=scripts scripts/module.lds



# Target to install modules

PHONY += modules_install
@@ -1743,7 +1743,9 @@ help: 
	@echo  '  clean           - remove generated files in module directory only'

	@echo  ''



PHONY += prepare

# no-op for external module builds

PHONY += prepare modules_prepare



endif # KBUILD_EXTMOD



# Single targets
@@ -1776,7 +1778,7 @@ MODORDER := .modules.tmp 
endif



PHONY += single_modpost

single_modpost: $(single-no-ko)

single_modpost: $(single-no-ko) modules_prepare

	$(Q){ $(foreach m, $(single-ko), echo $(extmod-prefix)$m;) } > $(MODORDER)

	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost

arch/arm/Makefile

+0 −4
Original line number Diff line number Diff line
@@ -16,10 +16,6 @@ LDFLAGS_vmlinux += --be8 
KBUILD_LDFLAGS_MODULE	+= --be8

endif



ifeq ($(CONFIG_ARM_MODULE_PLTS),y)

KBUILD_LDS_MODULE	+= $(srctree)/arch/arm/kernel/module.lds

endif



GZFLAGS		:=-9

#KBUILD_CFLAGS	+=-pipe

arch/arm/kernel/module.lds→arch/arm/include/asm/module.lds.h

+2 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifdef CONFIG_ARM_MODULE_PLTS

SECTIONS {

	.plt : { BYTE(0) }

	.init.plt : { BYTE(0) }

}

#endif

arch/arm64/Makefile

+0 −4
Original line number Diff line number Diff line
@@ -115,10 +115,6 @@ endif 


CHECKFLAGS	+= -D__aarch64__



ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)

KBUILD_LDS_MODULE	+= $(srctree)/arch/arm64/kernel/module.lds

endif



ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)

  KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY

  CC_FLAGS_FTRACE := -fpatchable-function-entry=2

arch/arm64/kernel/module.lds→arch/arm64/include/asm/module.lds.h

+2 −0
Original line number Diff line number Diff line 
#ifdef CONFIG_ARM64_MODULE_PLTS

SECTIONS {

	.plt (NOLOAD) : { BYTE(0) }

	.init.plt (NOLOAD) : { BYTE(0) }

	.text.ftrace_trampoline (NOLOAD) : { BYTE(0) }

}

#endif

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