| Message ID | 20200603053313.3863761-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | efi/libstub: refactor Makefile to not use lib-y syntax | expand |
On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > Documentation/kbuild/makefiles.rst says: > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > I want to disallow lib-y outside of them. > Why? > Add a custom rule to build lib.a, which is linked to the decompressor > for ARCH=x86, ARCH=arm. > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > way. > The code works perfectly fine as is, and I don't see what is fundamentally wrong with using static libraries outside of lib/ and arch/*/lib. Also, I would like this code to still be incorporated as a static library into arm64 as well, so that only pieces that are actually needed are incorporated into the final image. > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- > > arch/arm64/Makefile | 1 - > drivers/firmware/efi/Makefile | 2 +- > drivers/firmware/efi/libstub/Makefile | 51 +++++++++++++++------------ > 3 files changed, 30 insertions(+), 24 deletions(-) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 650e1185c190..ab79b20efc8d 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -145,7 +145,6 @@ export TEXT_OFFSET > > core-y += arch/arm64/ > libs-y := arch/arm64/lib/ $(libs-y) > -core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > > # Default target when executing plain make > boot := arch/arm64/boot > diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile > index 7a216984552b..317a05cd388b 100644 > --- a/drivers/firmware/efi/Makefile > +++ b/drivers/firmware/efi/Makefile > @@ -20,7 +20,7 @@ obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o > obj-$(CONFIG_UEFI_CPER) += cper.o > obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o > obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o > -subdir-$(CONFIG_EFI_STUB) += libstub > +obj-$(CONFIG_EFI_STUB) += libstub/ > obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_map.o > obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o > obj-$(CONFIG_EFI_TEST) += test/ > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index cce4a7436052..e4e9b17fa3b2 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -44,7 +44,7 @@ OBJECT_FILES_NON_STANDARD := y > # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. > KCOV_INSTRUMENT := n > > -lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ > +stub-obj-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ > file.o mem.o random.o randomalloc.o pci.o \ > skip_spaces.o lib-cmdline.o lib-ctype.o \ > alignedmem.o relocate.o vsprintf.o > @@ -55,15 +55,19 @@ efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c > $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE > $(call if_changed_rule,cc_o_c) > > -lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ > +stub-obj-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ > $(patsubst %.c,lib-%.o,$(efi-deps-y)) > > -lib-$(CONFIG_ARM) += arm32-stub.o > -lib-$(CONFIG_ARM64) += arm64-stub.o > -lib-$(CONFIG_X86) += x86-stub.o > +stub-obj-$(CONFIG_ARM) += arm32-stub.o > +stub-obj-$(CONFIG_ARM64) += arm64-stub.o > +stub-obj-$(CONFIG_X86) += x86-stub.o > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > +targets += $(stub-obj-y) > +stub-obj-y := $(patsubst %.o,%.stub.o, $(stub-obj-y)) > +targets += $(stub-obj-y) > + > # > # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the > # .bss section, so the .bss section of the EFI stub needs to be included in the > @@ -83,23 +87,6 @@ STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ > --rename-section .bss=.bss.efistub,load,alloc > STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS > > -# > -# arm64 puts the stub in the kernel proper, which will unnecessarily retain all > -# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. > -# So let's apply the __init annotations at the section level, by prefixing > -# the section names directly. This will ensure that even all the inline string > -# literals are covered. > -# The fact that the stub and the kernel proper are essentially the same binary > -# also means that we need to be extra careful to make sure that the stub does > -# not rely on any absolute symbol references, considering that the virtual > -# kernel mapping that the linker uses is not active yet when the stub is > -# executing. So build all C dependencies of the EFI stub into libstub, and do > -# a verification pass to see if any absolute relocations exist in any of the > -# object files. > -# > -extra-y := $(lib-y) > -lib-y := $(patsubst %.o,%.stub.o,$(lib-y)) > - > STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ > --prefix-symbols=__efistub_ > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS > @@ -121,3 +108,23 @@ quiet_cmd_stubcopy = STUBCPY $@ > /bin/false; \ > fi; \ > $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ > + > +# arm64 puts the stub in the kernel proper, which will unnecessarily retain all > +# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. > +# So let's apply the __init annotations at the section level, by prefixing > +# the section names directly. This will ensure that even all the inline string > +# literals are covered. > +# The fact that the stub and the kernel proper are essentially the same binary > +# also means that we need to be extra careful to make sure that the stub does > +# not rely on any absolute symbol references, considering that the virtual > +# kernel mapping that the linker uses is not active yet when the stub is > +# executing. So build all C dependencies of the EFI stub into libstub, and do > +# a verification pass to see if any absolute relocations exist in any of the > +# object files. > +# > +obj-$(CONFIG_ARM64) += $(stub-obj-y) > +extra-$(CONFIG_ARM) += lib.a > +extra-$(CONFIG_X86) += lib.a > + > +$(obj)/lib.a: $(addprefix $(obj)/, $(stub-obj-y)) FORCE > + $(call if_changed,ar) > -- > 2.25.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > Documentation/kbuild/makefiles.rst says: > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > I want to disallow lib-y outside of them. > > > > Why? Because I plan to remove lib-y entirely at some point. lib-y is not so useful to shrink the image size because: - An object in lib.a can be omitted only when no symbol in that object is referenced. This rarely happens. - lib-y objects are often exported by nature because lib-y is a collection of utility functions. Even if no in-tree user, we always need to keep them because EXPORT_SYMBOL() is the interface to modules. When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, I made some research. The benefit of lib-y is just 362 byte for x86_64_defconfig. ( Before: 26578002, After: 26578364) My hope is lib-y will be replaced by dead-code elimination or ultimately by LTO. drivers/firmware/efi/libstub/Makefile is the only Makefile that breaks the rule: "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > Add a custom rule to build lib.a, which is linked to the decompressor > > for ARCH=x86, ARCH=arm. > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > way. > > > > The code works perfectly fine as is, and I don't see what is > fundamentally wrong with using static libraries outside of lib/ and > arch/*/lib. The intended usage of lib-y is to hook lib.a to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. This Makefile is just what you found to work. > > Also, I would like this code to still be incorporated as a static > library into arm64 as well, so that only pieces that are actually > needed are incorporated into the final image. No. It is not working like that because you set lib.a to core-y. All objects in core-y are always linked to vmlinux. Thanks. > > > > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > > --- > > > > arch/arm64/Makefile | 1 - > > drivers/firmware/efi/Makefile | 2 +- > > drivers/firmware/efi/libstub/Makefile | 51 +++++++++++++++------------ > > 3 files changed, 30 insertions(+), 24 deletions(-) > > > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > > index 650e1185c190..ab79b20efc8d 100644 > > --- a/arch/arm64/Makefile > > +++ b/arch/arm64/Makefile > > @@ -145,7 +145,6 @@ export TEXT_OFFSET > > > > core-y += arch/arm64/ > > libs-y := arch/arm64/lib/ $(libs-y) > > -core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > > > > # Default target when executing plain make > > boot := arch/arm64/boot > > diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile > > index 7a216984552b..317a05cd388b 100644 > > --- a/drivers/firmware/efi/Makefile > > +++ b/drivers/firmware/efi/Makefile > > @@ -20,7 +20,7 @@ obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o > > obj-$(CONFIG_UEFI_CPER) += cper.o > > obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o > > obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o > > -subdir-$(CONFIG_EFI_STUB) += libstub > > +obj-$(CONFIG_EFI_STUB) += libstub/ > > obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_map.o > > obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o > > obj-$(CONFIG_EFI_TEST) += test/ > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > > index cce4a7436052..e4e9b17fa3b2 100644 > > --- a/drivers/firmware/efi/libstub/Makefile > > +++ b/drivers/firmware/efi/libstub/Makefile > > @@ -44,7 +44,7 @@ OBJECT_FILES_NON_STANDARD := y > > # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. > > KCOV_INSTRUMENT := n > > > > -lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ > > +stub-obj-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ > > file.o mem.o random.o randomalloc.o pci.o \ > > skip_spaces.o lib-cmdline.o lib-ctype.o \ > > alignedmem.o relocate.o vsprintf.o > > @@ -55,15 +55,19 @@ efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c > > $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE > > $(call if_changed_rule,cc_o_c) > > > > -lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ > > +stub-obj-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ > > $(patsubst %.c,lib-%.o,$(efi-deps-y)) > > > > -lib-$(CONFIG_ARM) += arm32-stub.o > > -lib-$(CONFIG_ARM64) += arm64-stub.o > > -lib-$(CONFIG_X86) += x86-stub.o > > +stub-obj-$(CONFIG_ARM) += arm32-stub.o > > +stub-obj-$(CONFIG_ARM64) += arm64-stub.o > > +stub-obj-$(CONFIG_X86) += x86-stub.o > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > +targets += $(stub-obj-y) > > +stub-obj-y := $(patsubst %.o,%.stub.o, $(stub-obj-y)) > > +targets += $(stub-obj-y) > > + > > # > > # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the > > # .bss section, so the .bss section of the EFI stub needs to be included in the > > @@ -83,23 +87,6 @@ STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ > > --rename-section .bss=.bss.efistub,load,alloc > > STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS > > > > -# > > -# arm64 puts the stub in the kernel proper, which will unnecessarily retain all > > -# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. > > -# So let's apply the __init annotations at the section level, by prefixing > > -# the section names directly. This will ensure that even all the inline string > > -# literals are covered. > > -# The fact that the stub and the kernel proper are essentially the same binary > > -# also means that we need to be extra careful to make sure that the stub does > > -# not rely on any absolute symbol references, considering that the virtual > > -# kernel mapping that the linker uses is not active yet when the stub is > > -# executing. So build all C dependencies of the EFI stub into libstub, and do > > -# a verification pass to see if any absolute relocations exist in any of the > > -# object files. > > -# > > -extra-y := $(lib-y) > > -lib-y := $(patsubst %.o,%.stub.o,$(lib-y)) > > - > > STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ > > --prefix-symbols=__efistub_ > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS > > @@ -121,3 +108,23 @@ quiet_cmd_stubcopy = STUBCPY $@ > > /bin/false; \ > > fi; \ > > $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ > > + > > +# arm64 puts the stub in the kernel proper, which will unnecessarily retain all > > +# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. > > +# So let's apply the __init annotations at the section level, by prefixing > > +# the section names directly. This will ensure that even all the inline string > > +# literals are covered. > > +# The fact that the stub and the kernel proper are essentially the same binary > > +# also means that we need to be extra careful to make sure that the stub does > > +# not rely on any absolute symbol references, considering that the virtual > > +# kernel mapping that the linker uses is not active yet when the stub is > > +# executing. So build all C dependencies of the EFI stub into libstub, and do > > +# a verification pass to see if any absolute relocations exist in any of the > > +# object files. > > +# > > +obj-$(CONFIG_ARM64) += $(stub-obj-y) > > +extra-$(CONFIG_ARM) += lib.a > > +extra-$(CONFIG_X86) += lib.a > > + > > +$(obj)/lib.a: $(addprefix $(obj)/, $(stub-obj-y)) FORCE > > + $(call if_changed,ar) > > -- > > 2.25.1 > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > I want to disallow lib-y outside of them. > > > > > > > Why? > > > Because I plan to remove lib-y entirely at some point. > > lib-y is not so useful to shrink the image size because: > > - An object in lib.a can be omitted only when no symbol > in that object is referenced. This rarely happens. > > - lib-y objects are often exported by nature > because lib-y is a collection of utility functions. > Even if no in-tree user, we always need to keep them > because EXPORT_SYMBOL() is the interface to modules. > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > I made some research. > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > ( Before: 26578002, After: 26578364) > > My hope is lib-y will be replaced by dead-code elimination or > ultimately by LTO. > > drivers/firmware/efi/libstub/Makefile > is the only Makefile that breaks the rule: > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > for ARCH=x86, ARCH=arm. > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > way. > > > > > > > The code works perfectly fine as is, and I don't see what is > > fundamentally wrong with using static libraries outside of lib/ and > > arch/*/lib. > > The intended usage of lib-y is to hook lib.a > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > This Makefile is just what you found to work. > > > > > > Also, I would like this code to still be incorporated as a static > > library into arm64 as well, so that only pieces that are actually > > needed are incorporated into the final image. > > No. > It is not working like that because you set > lib.a to core-y. > > All objects in core-y are always linked to vmlinux. > The lib.a file is passed to the linker as a static library, so it will only grab what it needs. For instance, if you build arm64 from mainline today, the efi_relocate_kernel will not be in the final image, even though it is built as part of libstub
On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > Why? > > > > > > Because I plan to remove lib-y entirely at some point. > > > > lib-y is not so useful to shrink the image size because: > > > > - An object in lib.a can be omitted only when no symbol > > in that object is referenced. This rarely happens. > > > > - lib-y objects are often exported by nature > > because lib-y is a collection of utility functions. > > Even if no in-tree user, we always need to keep them > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > I made some research. > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > ( Before: 26578002, After: 26578364) > > > > My hope is lib-y will be replaced by dead-code elimination or > > ultimately by LTO. > > > > drivers/firmware/efi/libstub/Makefile > > is the only Makefile that breaks the rule: > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > for ARCH=x86, ARCH=arm. > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > way. > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > fundamentally wrong with using static libraries outside of lib/ and > > > arch/*/lib. > > > > The intended usage of lib-y is to hook lib.a > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > This Makefile is just what you found to work. > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > library into arm64 as well, so that only pieces that are actually > > > needed are incorporated into the final image. > > > > No. > > It is not working like that because you set > > lib.a to core-y. > > > > All objects in core-y are always linked to vmlinux. > > > > The lib.a file is passed to the linker as a static library, so it will > only grab what it needs. > > For instance, if you build arm64 from mainline today, the > efi_relocate_kernel will not be in the final image, even though it is > built as part of libstub I built today's mainline kernel (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). I see it in vmlinux. $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 ... $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel ffff8000114afb90 t __efistub_efi_relocate_kernel
On Wed, 3 Jun 2020 at 10:59, Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > > > > Why? > > > > > > > > > Because I plan to remove lib-y entirely at some point. > > > > > > lib-y is not so useful to shrink the image size because: > > > > > > - An object in lib.a can be omitted only when no symbol > > > in that object is referenced. This rarely happens. > > > > > > - lib-y objects are often exported by nature > > > because lib-y is a collection of utility functions. > > > Even if no in-tree user, we always need to keep them > > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > > I made some research. > > > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > > ( Before: 26578002, After: 26578364) > > > > > > My hope is lib-y will be replaced by dead-code elimination or > > > ultimately by LTO. > > > > > > drivers/firmware/efi/libstub/Makefile > > > is the only Makefile that breaks the rule: > > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > > for ARCH=x86, ARCH=arm. > > > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > > way. > > > > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > > fundamentally wrong with using static libraries outside of lib/ and > > > > arch/*/lib. > > > > > > The intended usage of lib-y is to hook lib.a > > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > > > This Makefile is just what you found to work. > > > > > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > > library into arm64 as well, so that only pieces that are actually > > > > needed are incorporated into the final image. > > > > > > No. > > > It is not working like that because you set > > > lib.a to core-y. > > > > > > All objects in core-y are always linked to vmlinux. > > > > > > > The lib.a file is passed to the linker as a static library, so it will > > only grab what it needs. > > > > For instance, if you build arm64 from mainline today, the > > efi_relocate_kernel will not be in the final image, even though it is > > built as part of libstub > > > I built today's mainline kernel > (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). > > > I see it in vmlinux. > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 > ... > $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel > ffff8000114afb90 t __efistub_efi_relocate_kernel > That is strange. I tested this before, and it worked. Did anything change recently in the way the linker is invoked?
On Wed, Jun 3, 2020 at 6:02 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > On Wed, 3 Jun 2020 at 10:59, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > > > > > > > Why? > > > > > > > > > > > > Because I plan to remove lib-y entirely at some point. > > > > > > > > lib-y is not so useful to shrink the image size because: > > > > > > > > - An object in lib.a can be omitted only when no symbol > > > > in that object is referenced. This rarely happens. > > > > > > > > - lib-y objects are often exported by nature > > > > because lib-y is a collection of utility functions. > > > > Even if no in-tree user, we always need to keep them > > > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > > > I made some research. > > > > > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > > > ( Before: 26578002, After: 26578364) > > > > > > > > My hope is lib-y will be replaced by dead-code elimination or > > > > ultimately by LTO. > > > > > > > > drivers/firmware/efi/libstub/Makefile > > > > is the only Makefile that breaks the rule: > > > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > > > for ARCH=x86, ARCH=arm. > > > > > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > > > way. > > > > > > > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > > > fundamentally wrong with using static libraries outside of lib/ and > > > > > arch/*/lib. > > > > > > > > The intended usage of lib-y is to hook lib.a > > > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > > > > > This Makefile is just what you found to work. > > > > > > > > > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > > > library into arm64 as well, so that only pieces that are actually > > > > > needed are incorporated into the final image. > > > > > > > > No. > > > > It is not working like that because you set > > > > lib.a to core-y. > > > > > > > > All objects in core-y are always linked to vmlinux. > > > > > > > > > > The lib.a file is passed to the linker as a static library, so it will > > > only grab what it needs. > > > > > > For instance, if you build arm64 from mainline today, the > > > efi_relocate_kernel will not be in the final image, even though it is > > > built as part of libstub > > > > > > I built today's mainline kernel > > (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). > > > > > > I see it in vmlinux. > > > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 > > ... > > $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel > > ffff8000114afb90 t __efistub_efi_relocate_kernel > > > > That is strange. I tested this before, and it worked. > > Did anything change recently in the way the linker is invoked? Nothing recently. This is obvious result because drivers/firmware/efi/libstub/lib.a is passed after ----whole-archive flag. I guess the following commit is it, but it is already 3 years ago. commit 799c43415442414b1032580c47684cb709dfed6d (HEAD) Author: Nicholas Piggin <npiggin@gmail.com> Date: Fri Jun 9 15:24:17 2017 +1000 kbuild: thin archives make default for all archs Make thin archives build the default, but keep the config option to allow exemptions if any breakage can't be quickly solved. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
On Wed, 3 Jun 2020 at 11:15, Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Wed, Jun 3, 2020 at 6:02 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > On Wed, 3 Jun 2020 at 10:59, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > > > > > > > > > > Why? > > > > > > > > > > > > > > > Because I plan to remove lib-y entirely at some point. > > > > > > > > > > lib-y is not so useful to shrink the image size because: > > > > > > > > > > - An object in lib.a can be omitted only when no symbol > > > > > in that object is referenced. This rarely happens. > > > > > > > > > > - lib-y objects are often exported by nature > > > > > because lib-y is a collection of utility functions. > > > > > Even if no in-tree user, we always need to keep them > > > > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > > > > > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > > > > I made some research. > > > > > > > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > > > > ( Before: 26578002, After: 26578364) > > > > > > > > > > My hope is lib-y will be replaced by dead-code elimination or > > > > > ultimately by LTO. > > > > > > > > > > drivers/firmware/efi/libstub/Makefile > > > > > is the only Makefile that breaks the rule: > > > > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > > > > for ARCH=x86, ARCH=arm. > > > > > > > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > > > > way. > > > > > > > > > > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > > > > fundamentally wrong with using static libraries outside of lib/ and > > > > > > arch/*/lib. > > > > > > > > > > The intended usage of lib-y is to hook lib.a > > > > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > > > > > > > This Makefile is just what you found to work. > > > > > > > > > > > > > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > > > > library into arm64 as well, so that only pieces that are actually > > > > > > needed are incorporated into the final image. > > > > > > > > > > No. > > > > > It is not working like that because you set > > > > > lib.a to core-y. > > > > > > > > > > All objects in core-y are always linked to vmlinux. > > > > > > > > > > > > > The lib.a file is passed to the linker as a static library, so it will > > > > only grab what it needs. > > > > > > > > For instance, if you build arm64 from mainline today, the > > > > efi_relocate_kernel will not be in the final image, even though it is > > > > built as part of libstub > > > > > > > > > I built today's mainline kernel > > > (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). > > > > > > > > > I see it in vmlinux. > > > > > > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 > > > ... > > > $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel > > > ffff8000114afb90 t __efistub_efi_relocate_kernel > > > > > > > That is strange. I tested this before, and it worked. > > > > Did anything change recently in the way the linker is invoked? > > > Nothing recently. > > This is obvious result because > drivers/firmware/efi/libstub/lib.a > is passed after ----whole-archive flag. > > > I guess the following commit is it, > but it is already 3 years ago. > Right. So that means there is no point at all in using static libraries, no? Or does --whole-archive still allow duplicate definitions like static libraries do usually?
On Wed, Jun 3, 2020 at 6:16 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > On Wed, 3 Jun 2020 at 11:15, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > On Wed, Jun 3, 2020 at 6:02 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > On Wed, 3 Jun 2020 at 10:59, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > > > > > > > > > > > > > Why? > > > > > > > > > > > > > > > > > > Because I plan to remove lib-y entirely at some point. > > > > > > > > > > > > lib-y is not so useful to shrink the image size because: > > > > > > > > > > > > - An object in lib.a can be omitted only when no symbol > > > > > > in that object is referenced. This rarely happens. > > > > > > > > > > > > - lib-y objects are often exported by nature > > > > > > because lib-y is a collection of utility functions. > > > > > > Even if no in-tree user, we always need to keep them > > > > > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > > > > > > > > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > > > > > I made some research. > > > > > > > > > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > > > > > ( Before: 26578002, After: 26578364) > > > > > > > > > > > > My hope is lib-y will be replaced by dead-code elimination or > > > > > > ultimately by LTO. > > > > > > > > > > > > drivers/firmware/efi/libstub/Makefile > > > > > > is the only Makefile that breaks the rule: > > > > > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > > > > > for ARCH=x86, ARCH=arm. > > > > > > > > > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > > > > > way. > > > > > > > > > > > > > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > > > > > fundamentally wrong with using static libraries outside of lib/ and > > > > > > > arch/*/lib. > > > > > > > > > > > > The intended usage of lib-y is to hook lib.a > > > > > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > > > > > > > > > This Makefile is just what you found to work. > > > > > > > > > > > > > > > > > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > > > > > library into arm64 as well, so that only pieces that are actually > > > > > > > needed are incorporated into the final image. > > > > > > > > > > > > No. > > > > > > It is not working like that because you set > > > > > > lib.a to core-y. > > > > > > > > > > > > All objects in core-y are always linked to vmlinux. > > > > > > > > > > > > > > > > The lib.a file is passed to the linker as a static library, so it will > > > > > only grab what it needs. > > > > > > > > > > For instance, if you build arm64 from mainline today, the > > > > > efi_relocate_kernel will not be in the final image, even though it is > > > > > built as part of libstub > > > > > > > > > > > > I built today's mainline kernel > > > > (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). > > > > > > > > > > > > I see it in vmlinux. > > > > > > > > > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 > > > > ... > > > > $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel > > > > ffff8000114afb90 t __efistub_efi_relocate_kernel > > > > > > > > > > That is strange. I tested this before, and it worked. > > > > > > Did anything change recently in the way the linker is invoked? > > > > > > Nothing recently. > > > > This is obvious result because > > drivers/firmware/efi/libstub/lib.a > > is passed after ----whole-archive flag. > > > > > > I guess the following commit is it, > > but it is already 3 years ago. > > > > Right. > > So that means there is no point at all in using static libraries, no? > Or does --whole-archive still allow duplicate definitions like static > libraries do usually? --whole-archive literally links the whole of the archive. If there are duplicate definitions, the linking fails due to multiple definition. So, --whole-archive is similar to linking .o files in this regard. There is a point for arm and x86 because the decompressor link does not use --whole-archive. As for arm64, there is no point, but you can pass lib.a after --no-whole-archive by the following patch. diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 650e1185c190..48a6afa774fc 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -145,7 +145,7 @@ export TEXT_OFFSET core-y += arch/arm64/ libs-y := arch/arm64/lib/ $(libs-y) -core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a +libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a # Default target when executing plain make boot := arch/arm64/boot Then, _efistub_efi_low_alloc_above and __efistub_efi_relocate_kernel will be dropped. If you like the static library do you want me to send v2?
On Wed, 3 Jun 2020 at 13:23, Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Wed, Jun 3, 2020 at 6:16 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > On Wed, 3 Jun 2020 at 11:15, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > On Wed, Jun 3, 2020 at 6:02 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > On Wed, 3 Jun 2020 at 10:59, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > On Wed, Jun 3, 2020 at 5:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > > > On Wed, 3 Jun 2020 at 10:36, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > > > On Wed, Jun 3, 2020 at 3:45 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > > > > > > > > > > > > > > On Wed, 3 Jun 2020 at 07:34, Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > > > > > > > > > > > > > > > Documentation/kbuild/makefiles.rst says: > > > > > > > > > > > > > > > > > > Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. > > > > > > > > > > > > > > > > > > I want to disallow lib-y outside of them. > > > > > > > > > > > > > > > > > > > > > > > > > Why? > > > > > > > > > > > > > > > > > > > > > Because I plan to remove lib-y entirely at some point. > > > > > > > > > > > > > > lib-y is not so useful to shrink the image size because: > > > > > > > > > > > > > > - An object in lib.a can be omitted only when no symbol > > > > > > > in that object is referenced. This rarely happens. > > > > > > > > > > > > > > - lib-y objects are often exported by nature > > > > > > > because lib-y is a collection of utility functions. > > > > > > > Even if no in-tree user, we always need to keep them > > > > > > > because EXPORT_SYMBOL() is the interface to modules. > > > > > > > > > > > > > > > > > > > > > When I worked on commit 7273ad2b08f8ac9563579d16a3cf528857b26f49, > > > > > > > I made some research. > > > > > > > > > > > > > > The benefit of lib-y is just 362 byte for x86_64_defconfig. > > > > > > > ( Before: 26578002, After: 26578364) > > > > > > > > > > > > > > My hope is lib-y will be replaced by dead-code elimination or > > > > > > > ultimately by LTO. > > > > > > > > > > > > > > drivers/firmware/efi/libstub/Makefile > > > > > > > is the only Makefile that breaks the rule: > > > > > > > "Use of lib-y is normally restricted to `lib/` and `arch/*/lib`" > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Add a custom rule to build lib.a, which is linked to the decompressor > > > > > > > > > for ARCH=x86, ARCH=arm. > > > > > > > > > > > > > > > > > > For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary > > > > > > > > > way. > > > > > > > > > > > > > > > > > > > > > > > > > The code works perfectly fine as is, and I don't see what is > > > > > > > > fundamentally wrong with using static libraries outside of lib/ and > > > > > > > > arch/*/lib. > > > > > > > > > > > > > > The intended usage of lib-y is to hook lib.a > > > > > > > to scripts/vmlinux.sh via KBUILD_VMLINUX_LIBS. > > > > > > > > > > > > > > This Makefile is just what you found to work. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Also, I would like this code to still be incorporated as a static > > > > > > > > library into arm64 as well, so that only pieces that are actually > > > > > > > > needed are incorporated into the final image. > > > > > > > > > > > > > > No. > > > > > > > It is not working like that because you set > > > > > > > lib.a to core-y. > > > > > > > > > > > > > > All objects in core-y are always linked to vmlinux. > > > > > > > > > > > > > > > > > > > The lib.a file is passed to the linker as a static library, so it will > > > > > > only grab what it needs. > > > > > > > > > > > > For instance, if you build arm64 from mainline today, the > > > > > > efi_relocate_kernel will not be in the final image, even though it is > > > > > > built as part of libstub > > > > > > > > > > > > > > > I built today's mainline kernel > > > > > (d6f9469a03d832dcd17041ed67774ffb5f3e73b3). > > > > > > > > > > > > > > > I see it in vmlinux. > > > > > > > > > > > > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig > > > > > $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j24 > > > > > ... > > > > > $ aarch64-linux-gnu-nm -n vmlinux | grep efi_relocate_kernel > > > > > ffff8000114afb90 t __efistub_efi_relocate_kernel > > > > > > > > > > > > > That is strange. I tested this before, and it worked. > > > > > > > > Did anything change recently in the way the linker is invoked? > > > > > > > > > Nothing recently. > > > > > > This is obvious result because > > > drivers/firmware/efi/libstub/lib.a > > > is passed after ----whole-archive flag. > > > > > > > > > I guess the following commit is it, > > > but it is already 3 years ago. > > > > > > > Right. > > > > So that means there is no point at all in using static libraries, no? > > Or does --whole-archive still allow duplicate definitions like static > > libraries do usually? > > > --whole-archive literally links the whole of the archive. > If there are duplicate definitions, the linking fails > due to multiple definition. > So, --whole-archive is similar to linking .o files > in this regard. > > > There is a point for arm and x86 because > the decompressor link does not use --whole-archive. > > As for arm64, there is no point, > but you can pass lib.a after --no-whole-archive > by the following patch. > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 650e1185c190..48a6afa774fc 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -145,7 +145,7 @@ export TEXT_OFFSET > > core-y += arch/arm64/ > libs-y := arch/arm64/lib/ $(libs-y) > -core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > +libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > > # Default target when executing plain make > boot := arch/arm64/boot > > > > Then, _efistub_efi_low_alloc_above > and __efistub_efi_relocate_kernel will be dropped. > > > If you like the static library > do you want me to send v2? > Yes please
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 650e1185c190..ab79b20efc8d 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -145,7 +145,6 @@ export TEXT_OFFSET core-y += arch/arm64/ libs-y := arch/arm64/lib/ $(libs-y) -core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a # Default target when executing plain make boot := arch/arm64/boot diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index 7a216984552b..317a05cd388b 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -20,7 +20,7 @@ obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o obj-$(CONFIG_UEFI_CPER) += cper.o obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o -subdir-$(CONFIG_EFI_STUB) += libstub +obj-$(CONFIG_EFI_STUB) += libstub/ obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_map.o obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o obj-$(CONFIG_EFI_TEST) += test/ diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index cce4a7436052..e4e9b17fa3b2 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -44,7 +44,7 @@ OBJECT_FILES_NON_STANDARD := y # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. KCOV_INSTRUMENT := n -lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ +stub-obj-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ file.o mem.o random.o randomalloc.o pci.o \ skip_spaces.o lib-cmdline.o lib-ctype.o \ alignedmem.o relocate.o vsprintf.o @@ -55,15 +55,19 @@ efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE $(call if_changed_rule,cc_o_c) -lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ +stub-obj-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o fdt.o string.o \ $(patsubst %.c,lib-%.o,$(efi-deps-y)) -lib-$(CONFIG_ARM) += arm32-stub.o -lib-$(CONFIG_ARM64) += arm64-stub.o -lib-$(CONFIG_X86) += x86-stub.o +stub-obj-$(CONFIG_ARM) += arm32-stub.o +stub-obj-$(CONFIG_ARM64) += arm64-stub.o +stub-obj-$(CONFIG_X86) += x86-stub.o CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) +targets += $(stub-obj-y) +stub-obj-y := $(patsubst %.o,%.stub.o, $(stub-obj-y)) +targets += $(stub-obj-y) + # # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the # .bss section, so the .bss section of the EFI stub needs to be included in the @@ -83,23 +87,6 @@ STUBCOPY_FLAGS-$(CONFIG_ARM) += --rename-section .data=.data.efistub \ --rename-section .bss=.bss.efistub,load,alloc STUBCOPY_RELOC-$(CONFIG_ARM) := R_ARM_ABS -# -# arm64 puts the stub in the kernel proper, which will unnecessarily retain all -# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. -# So let's apply the __init annotations at the section level, by prefixing -# the section names directly. This will ensure that even all the inline string -# literals are covered. -# The fact that the stub and the kernel proper are essentially the same binary -# also means that we need to be extra careful to make sure that the stub does -# not rely on any absolute symbol references, considering that the virtual -# kernel mapping that the linker uses is not active yet when the stub is -# executing. So build all C dependencies of the EFI stub into libstub, and do -# a verification pass to see if any absolute relocations exist in any of the -# object files. -# -extra-y := $(lib-y) -lib-y := $(patsubst %.o,%.stub.o,$(lib-y)) - STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ --prefix-symbols=__efistub_ STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS @@ -121,3 +108,23 @@ quiet_cmd_stubcopy = STUBCPY $@ /bin/false; \ fi; \ $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@ + +# arm64 puts the stub in the kernel proper, which will unnecessarily retain all +# code indefinitely unless it is annotated as __init/__initdata/__initconst etc. +# So let's apply the __init annotations at the section level, by prefixing +# the section names directly. This will ensure that even all the inline string +# literals are covered. +# The fact that the stub and the kernel proper are essentially the same binary +# also means that we need to be extra careful to make sure that the stub does +# not rely on any absolute symbol references, considering that the virtual +# kernel mapping that the linker uses is not active yet when the stub is +# executing. So build all C dependencies of the EFI stub into libstub, and do +# a verification pass to see if any absolute relocations exist in any of the +# object files. +# +obj-$(CONFIG_ARM64) += $(stub-obj-y) +extra-$(CONFIG_ARM) += lib.a +extra-$(CONFIG_X86) += lib.a + +$(obj)/lib.a: $(addprefix $(obj)/, $(stub-obj-y)) FORCE + $(call if_changed,ar)
Documentation/kbuild/makefiles.rst says: Use of lib-y is normally restricted to `lib/` and `arch/*/lib`. I want to disallow lib-y outside of them. Add a custom rule to build lib.a, which is linked to the decompressor for ARCH=x86, ARCH=arm. For ARCH=arm64, use obj-y to link objects to vmlinux in the ordinary way. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- arch/arm64/Makefile | 1 - drivers/firmware/efi/Makefile | 2 +- drivers/firmware/efi/libstub/Makefile | 51 +++++++++++++++------------ 3 files changed, 30 insertions(+), 24 deletions(-)