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linux/scripts/Makefile.vmlinux

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kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
2022-05-13 14:39:22 +03:00
# SPDX-License-Identifier: GPL-2.0-only
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated When include/linux/export-internal.h is updated, .vmlinux.export.o must be rebuilt, but it does not happen because its rule is hidden behind scripts/link-vmlinux.sh. Move it out of the shell script, so that Make can see the dependency between vmlinux and .vmlinux.export.o. Move the vmlinux rule to scripts/Makefile.vmlinux. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-09-28 09:39:41 +03:00
PHONY := __default
__default: vmlinux
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
2022-05-13 14:39:22 +03:00
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
# for c_flags
include $(srctree)/scripts/Makefile.lib
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated When include/linux/export-internal.h is updated, .vmlinux.export.o must be rebuilt, but it does not happen because its rule is hidden behind scripts/link-vmlinux.sh. Move it out of the shell script, so that Make can see the dependency between vmlinux and .vmlinux.export.o. Move the vmlinux rule to scripts/Makefile.vmlinux. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-09-28 09:39:41 +03:00
targets :=
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
2022-05-13 14:39:22 +03:00
quiet_cmd_cc_o_c = CC $@
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
%.o: %.c FORCE
$(call if_changed_dep,cc_o_c)
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated When include/linux/export-internal.h is updated, .vmlinux.export.o must be rebuilt, but it does not happen because its rule is hidden behind scripts/link-vmlinux.sh. Move it out of the shell script, so that Make can see the dependency between vmlinux and .vmlinux.export.o. Move the vmlinux rule to scripts/Makefile.vmlinux. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-09-28 09:39:41 +03:00
ifdef CONFIG_MODULES
kbuild: Fix CFI hash randomization with KASAN Clang emits a asan.module_ctor constructor to each object file when KASAN is enabled, and these functions are indirectly called in do_ctors. With CONFIG_CFI_CLANG, the compiler also emits a CFI type hash before each address-taken global function so they can pass indirect call checks. However, in commit 0c3e806ec0f9 ("x86/cfi: Add boot time hash randomization"), x86 implemented boot time hash randomization, which relies on the .cfi_sites section generated by objtool. As objtool is run against vmlinux.o instead of individual object files with X86_KERNEL_IBT (enabled by default), CFI types in object files that are not part of vmlinux.o end up not being included in .cfi_sites, and thus won't get randomized and trip CFI when called. Only .vmlinux.export.o and init/version-timestamp.o are linked into vmlinux separately from vmlinux.o. As these files don't contain any functions, disable KASAN for both of them to avoid breaking hash randomization. Link: https://github.com/ClangBuiltLinux/linux/issues/1742 Fixes: 0c3e806ec0f9 ("x86/cfi: Add boot time hash randomization") Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230112224948.1479453-2-samitolvanen@google.com
2023-01-13 01:49:48 +03:00
KASAN_SANITIZE_.vmlinux.export.o := n
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated When include/linux/export-internal.h is updated, .vmlinux.export.o must be rebuilt, but it does not happen because its rule is hidden behind scripts/link-vmlinux.sh. Move it out of the shell script, so that Make can see the dependency between vmlinux and .vmlinux.export.o. Move the vmlinux rule to scripts/Makefile.vmlinux. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-09-28 09:39:41 +03:00
targets += .vmlinux.export.o
vmlinux: .vmlinux.export.o
endif
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
# Final link of vmlinux with optional arch pass after final link
cmd_link_vmlinux = \
$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
targets += vmlinux
vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
+$(call if_changed_dep,link_vmlinux)
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS include/{linux,asm-generic}/export.h defines a weak symbol, __crc_* as a placeholder. Genksyms writes the version CRCs into the linker script, which will be used for filling the __crc_* symbols. The linker script format depends on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset to the reference of CRC. It is time to get rid of this complexity. Now that modpost parses text files (.*.cmd) to collect all the CRCs, it can generate C code that will be linked to the vmlinux or modules. Generate a new C file, .vmlinux.export.c, which contains the CRCs of symbols exported by vmlinux. It is compiled and linked to vmlinux in scripts/link-vmlinux.sh. Put the CRCs of symbols exported by modules into the existing *.mod.c files. No additional build step is needed for modules. As before, *.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal. No linker magic is used here. The new C implementation works in the same way, whether CONFIG_RELOCATABLE is enabled or not. CONFIG_MODULE_REL_CRCS is no longer needed. Previously, Kbuild invoked additional $(LD) to update the CRCs in objects, but this step is unneeded too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
2022-05-13 14:39:22 +03:00
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
PHONY += FORCE
FORCE:
# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.
existing-targets := $(wildcard $(sort $(targets)))
-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
.PHONY: $(PHONY)
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