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kbuild: factor out the common objtool arguments
JIRA: https://issues.redhat.com/browse/RHEL-2773 Conflicts: scripts/Makefile.build scripts/Makefile.lib scripts/link-vmlinux.sh - Undo previous RHEL-only conflict workarounds in these files from cs-9 commits that avoided this backport: - 69cd8c6 ("x86: Add prefix symbols for function padding") - 2354000 ("objtool: Add entry UNRET validation") - 73afd5e ("objtool: Add --hacks=skylake") - 21de65c ("x86/ibt: Implement FineIBT") - af8931b ("kbuild: Fixup the IBT kbuild changes") - eeb9f34 ("x86/srso: Fix unret validation dependencies") scripts/Makefile.vmlinux_o - cs-9 is doesn't have 9ec6ab6 ("kbuild: use objtool-args-y to clean up objtool arguments"), add CONFIG_CPU_SRSO check to objtool_args and not vmlinux-objtool-args commit b42d230 Author: Masahiro Yamada <masahiroy@kernel.org> Date: Sun May 29 00:47:04 2022 +0900 kbuild: factor out the common objtool arguments scripts/Makefile.build and scripts/link-vmlinux.sh have similar setups for the objtool arguments. It was difficult to factor out them because all the vmlinux build rules were written in a shell script. It is somewhat tedious to touch the two files every time a new objtool option is supported. To reduce the code duplication, move the objtool for vmlinux.o into scripts/Makefile.vmlinux_o. Then, move the common macros to Makefile.lib so they are shared between Makefile.build and Makefile.vmlinux_o. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
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‎scripts/Makefile.build‎

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Original file line numberDiff line numberDiff line change
@@ -229,34 +229,6 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
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$(sub_cmd_record_mcount))
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endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
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232-
ifdef CONFIG_OBJTOOL
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objtool := $(objtree)/tools/objtool/objtool
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objtool_args = \
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$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
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$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
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$(if $(CONFIG_CALL_DEPTH_TRACKING), --hacks=skylake) \
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$(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
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$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
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$(if $(CONFIG_UNWINDER_ORC), --orc) \
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$(if $(CONFIG_RETPOLINE), --retpoline) \
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$(if $(CONFIG_RETHUNK), --rethunk) \
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$(if $(CONFIG_SLS), --sls) \
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$(if $(CONFIG_STACK_VALIDATION), --stackval) \
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$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
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$(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess) \
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$(if $(linked-object), --link) \
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$(if $(part-of-module), --module) \
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$(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
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$(if $(CONFIG_PREFIX_SYMBOLS), --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)) \
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$(if $(CONFIG_FINEIBT), --cfi)
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cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
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cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
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endif # CONFIG_OBJTOOL
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ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
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# Skip objtool for LLVM bitcode

‎scripts/Makefile.lib‎

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Original file line numberDiff line numberDiff line change
@@ -246,6 +246,34 @@ ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
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mod-prelink-ext := .prelink
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endif
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249+
ifdef CONFIG_OBJTOOL
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objtool := $(objtree)/tools/objtool/objtool
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objtool_args = \
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$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
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$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
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$(if $(CONFIG_CALL_DEPTH_TRACKING), --hacks=skylake) \
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$(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
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$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
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$(if $(CONFIG_UNWINDER_ORC), --orc) \
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$(if $(CONFIG_RETPOLINE), --retpoline) \
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$(if $(CONFIG_RETHUNK), --rethunk) \
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$(if $(CONFIG_SLS), --sls) \
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$(if $(CONFIG_STACK_VALIDATION), --stackval) \
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$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
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$(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess) \
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$(if $(linked-object), --link) \
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$(if $(part-of-module), --module) \
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$(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
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$(if $(CONFIG_PREFIX_SYMBOLS), --prefix=$(CONFIG_FUNCTION_PADDING_BYTES)) \
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$(if $(CONFIG_FINEIBT), --cfi)
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cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
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cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
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endif # CONFIG_OBJTOOL
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# Useful for describing the dependency of composite objects
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# Usage:
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# $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)

‎scripts/Makefile.vmlinux_o‎

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Original file line numberDiff line numberDiff line change
@@ -6,6 +6,9 @@ __default: vmlinux.o
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for objtool
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include $(srctree)/scripts/Makefile.lib
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# Generate a linker script to ensure correct ordering of initcalls for Clang LTO
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# ---------------------------------------------------------------------------
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@@ -24,6 +27,27 @@ ifdef CONFIG_LTO_CLANG
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initcalls-lds := .tmp_initcalls.lds
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endif
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# objtool for vmlinux.o
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# ---------------------------------------------------------------------------
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#
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# For LTO and IBT, objtool doesn't run on individual translation units.
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# Run everything on vmlinux instead.
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objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
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# Reuse objtool_args defined in scripts/Makefile.lib if LTO or IBT is enabled.
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#
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# Add some more flags as needed.
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# --no-unreachable and --link might be added twice, but it is fine.
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#
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# Expand objtool_args to a simple variable to avoid circular reference.
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objtool_args := \
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$(if $(delay-objtool),$(objtool_args)) \
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$(if $(CONFIG_NOINSTR_VALIDATION), --noinstr $(if $(or $(CONFIG_CPU_UNRET_ENTRY),$(CONFIG_CPU_SRSO)), --unret)) \
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$(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
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--link
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# Link of vmlinux.o used for section mismatch analysis
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# ---------------------------------------------------------------------------
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@@ -33,9 +57,11 @@ quiet_cmd_ld_vmlinux.o = LD $@
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$(addprefix -T , $(initcalls-lds)) \
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--whole-archive $(KBUILD_VMLINUX_OBJS) --no-whole-archive \
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--start-group $(KBUILD_VMLINUX_LIBS) --end-group \
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$(cmd_objtool)
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define rule_ld_vmlinux.o
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$(call cmd_and_savecmd,ld_vmlinux.o)
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$(call cmd,gen_objtooldep)
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endef
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vmlinux.o: $(initcalls-lds) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS) FORCE

‎scripts/link-vmlinux.sh‎

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Original file line numberDiff line numberDiff line change
@@ -52,106 +52,6 @@ info()
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printf " %-7s %s\n" "${1}" "${2}"
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}
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objtool_link()
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{
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local objtoolcmd;
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local objtoolopt;
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if ! is_enabled CONFIG_OBJTOOL; then
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return;
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fi
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# RHEL-only workaround for missing upstream b42d23065024
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# ("kbuild: factor out the common objtool arguments"), objtool
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# is only enabled for vmlinux.o under the following conditions:
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#
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# scripts/Makefile.lib
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# delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
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#
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# scripts/Makefile.vmlinux_o
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# objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
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if ! (is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT || is_enabled CONFIG_NOINSTR_VALIDATION); then
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return
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fi
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if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
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# For LTO and IBT, objtool doesn't run on individual
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# translation units. Run everything on vmlinux instead.
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if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then
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objtoolopt="${objtoolopt} --hacks=jump_label"
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fi
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if is_enabled CONFIG_HAVE_NOINSTR_HACK; then
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objtoolopt="${objtoolopt} --hacks=noinstr"
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fi
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if is_enabled CONFIG_CALL_DEPTH_TRACKING; then
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objtoolopt="${objtoolopt} --hacks=skylake"
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fi
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if is_enabled CONFIG_X86_KERNEL_IBT; then
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objtoolopt="${objtoolopt} --ibt"
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fi
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if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
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objtoolopt="${objtoolopt} --mcount"
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fi
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if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
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objtoolopt="${objtoolopt} --mnop"
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fi
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if is_enabled CONFIG_UNWINDER_ORC; then
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objtoolopt="${objtoolopt} --orc"
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fi
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if is_enabled CONFIG_RETPOLINE; then
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objtoolopt="${objtoolopt} --retpoline"
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fi
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if is_enabled CONFIG_SLS; then
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objtoolopt="${objtoolopt} --sls"
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fi
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if is_enabled CONFIG_STACK_VALIDATION; then
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objtoolopt="${objtoolopt} --stackval"
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fi
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if is_enabled CONFIG_HAVE_STATIC_CALL_INLINE; then
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objtoolopt="${objtoolopt} --static-call"
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fi
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if is_enabled CONFIG_HAVE_UACCESS_VALIDATION; then
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objtoolopt="${objtoolopt} --uaccess"
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fi
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fi
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if is_enabled CONFIG_NOINSTR_VALIDATION; then
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objtoolopt="${objtoolopt} --noinstr"
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if is_enabled CONFIG_CPU_UNRET_ENTRY || is_enabled CONFIG_CPU_SRSO; then
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objtoolopt="${objtoolopt} --unret"
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fi
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fi
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if is_enabled CONFIG_PREFIX_SYMBOLS; then
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objtoolopt="${objtoolopt} --prefix=$(config_value "CONFIG_FUNCTION_PADDING_BYTES")"
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fi
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if [ -n "${objtoolopt}" ]; then
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if is_enabled CONFIG_GCOV_KERNEL; then
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objtoolopt="${objtoolopt} --no-unreachable"
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fi
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objtoolopt="${objtoolopt} --link"
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info OBJTOOL ${1}
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tools/objtool/objtool ${objtoolopt} ${1}
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fi
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}
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# Link of vmlinux
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# ${1} - output file
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# ${2}, ${3}, ... - optional extra .o files
@@ -342,7 +242,6 @@ ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
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343243
#link vmlinux.o
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${MAKE} -f "${srctree}/scripts/Makefile.vmlinux_o"
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objtool_link vmlinux.o
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347246
# modpost vmlinux.o to check for section mismatches
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${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1

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