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Message-ID: <CA+icZUWkOrWYSY3ixxfF=vsuq1xw3mU+p3NMqBpY0OpM02916g@mail.gmail.com>
Date: Sun, 29 May 2022 16:46:30 +0200
From: Sedat Dilek <sedat.dilek@...il.com>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: linux-kbuild@...r.kernel.org,
Nick Desaulniers <ndesaulniers@...gle.com>,
linux-kernel@...r.kernel.org, Josh Poimboeuf <jpoimboe@...hat.com>,
Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH 4/4] kbuild: factor out the common objtool arguments
On Sat, May 28, 2022 at 9:45 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> scripts/Makefile.build and scripts/link-vmlinux.sh have similar setups
> for the objtool arguments.
>
> It is difficult to factor out them because the vmlinux build rule is
> 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, implement everything about objtool in
> Makefile.
>
> Move the objtool for vmlinux.o into scripts/Makefile.vmlinux_o.
>
> Move the common macros to Makefile.lib so they are shared by
> Makefile.build and Makefile.vmlinux_o.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
With some comments (see below).
Tested-by: Sedat Dilek <sedat.dilek@...il.com> # LLVM-14 (x86-64)
-Sedat-
> ---
>
> scripts/Makefile.build | 26 --------------
> scripts/Makefile.lib | 26 ++++++++++++++
> scripts/Makefile.vmlinux_o | 26 ++++++++++++++
> scripts/link-vmlinux.sh | 71 --------------------------------------
> 4 files changed, 52 insertions(+), 97 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 4cb7145071b9..1f01ac65c0cd 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -210,38 +210,12 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
> $(sub_cmd_record_mcount))
> endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
>
> -ifdef CONFIG_OBJTOOL
> -
> -objtool := $(objtree)/tools/objtool/objtool
> -
> -objtool_args = \
> - $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
> - $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
> - $(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
> - $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
> - $(if $(CONFIG_UNWINDER_ORC), --orc) \
> - $(if $(CONFIG_RETPOLINE), --retpoline) \
> - $(if $(CONFIG_SLS), --sls) \
> - $(if $(CONFIG_STACK_VALIDATION), --stackval) \
> - $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
> - --uaccess \
> - $(if $(delay-objtool), --link) \
> - $(if $(part-of-module), --module) \
> - $(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
> -
> -cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
> -cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
> -
> -endif # CONFIG_OBJTOOL
> -
> # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
> # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
> # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
>
^^ What is with this block?
If this belongs together with objtool - shall this be moved, too?
> is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
>
> -delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
> -
> $(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y))
>
> ifdef CONFIG_TRIM_UNUSED_KSYMS
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index f75138385449..f691fb231ce5 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -225,6 +225,32 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \
> $(addprefix -I,$(DTC_INCLUDE)) \
> -undef -D__DTS__
>
> +ifdef CONFIG_OBJTOOL
> +
> +objtool := $(objtree)/tools/objtool/objtool
> +
> +objtool_args = \
> + $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
> + $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
> + $(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
> + $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
> + $(if $(CONFIG_UNWINDER_ORC), --orc) \
> + $(if $(CONFIG_RETPOLINE), --retpoline) \
> + $(if $(CONFIG_SLS), --sls) \
> + $(if $(CONFIG_STACK_VALIDATION), --stackval) \
> + $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
> + --uaccess \
> + $(if $(delay-objtool), --link) \
> + $(if $(part-of-module), --module) \
> + $(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
> +
> +delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
> +
> +cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
> +cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
> +
> +endif # CONFIG_OBJTOOL
> +
> # Useful for describing the dependency of composite objects
> # Usage:
> # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)
> diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
> index a9b375ca86d5..3c97a1564947 100644
> --- a/scripts/Makefile.vmlinux_o
> +++ b/scripts/Makefile.vmlinux_o
> @@ -6,6 +6,9 @@ __default: vmlinux.o
> include include/config/auto.conf
> include $(srctree)/scripts/Kbuild.include
>
> +# for objtool
> +include $(srctree)/scripts/Makefile.lib
> +
> # Generate a linker script to ensure correct ordering of initcalls for Clang LTO
> # ---------------------------------------------------------------------------
>
> @@ -24,6 +27,27 @@ ifdef CONFIG_LTO_CLANG
> initcalls-lds := .tmp_initcalls.lds
> endif
>
> +# objtool for vmlinux.o
> +# ---------------------------------------------------------------------------
> +#
> +# For LTO and IBT, objtool doesn't run on individual translation units.
> +# Run everything on vmlinux instead.
> +
> +objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
> +
> +# Reuse objtool_args defined in scripts/Makefile.lib if LTO or IBT is enabled.
> +#
> +# Add some more flags as needed.
> +# --no-unreachable and --link might be added twice, but it is fine.
> +#
> +# Expand objtool_args to a simple variable to avoid circular reference.
> +
> +objtool_args := \
> + $(if $(delay-objtool),$(objtool_args)) \
> + $(if $(CONFIG_NOINSTR_VALIDATION), --noinstr) \
> + $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
> + --link
> +
> # Link of vmlinux.o used for section mismatch analysis
> # ---------------------------------------------------------------------------
>
> @@ -33,9 +57,11 @@ quiet_cmd_ld_vmlinux.o = LD $@
> $(addprefix -T , $(initcalls-lds)) \
> --whole-archive $(KBUILD_VMLINUX_OBJS) --no-whole-archive \
> --start-group $(KBUILD_VMLINUX_LIBS) --end-group \
> + $(cmd_objtool)
>
> define rule_ld_vmlinux.o
> $(call cmd_and_savecmd,ld_vmlinux.o)
> + $(call cmd,gen_objtooldep)
> endef
>
> vmlinux.o: $(initcalls-lds) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS) FORCE
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 90680b6bd710..1ac4e180fa3f 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -45,76 +45,6 @@ info()
> printf " %-7s %s\n" "${1}" "${2}"
> }
>
> -objtool_link()
> -{
> - local objtoolcmd;
> - local objtoolopt;
> -
> - if ! is_enabled CONFIG_OBJTOOL; then
> - return;
> - fi
> -
> - if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
> -
> - # For LTO and IBT, objtool doesn't run on individual
> - # translation units. Run everything on vmlinux instead.
> -
> - if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then
> - objtoolopt="${objtoolopt} --hacks=jump_label"
> - fi
> -
> - if is_enabled CONFIG_HAVE_NOINSTR_HACK; then
> - objtoolopt="${objtoolopt} --hacks=noinstr"
> - fi
> -
> - if is_enabled CONFIG_X86_KERNEL_IBT; then
> - objtoolopt="${objtoolopt} --ibt"
> - fi
> -
> - if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
> - objtoolopt="${objtoolopt} --mcount"
> - fi
> -
> - if is_enabled CONFIG_UNWINDER_ORC; then
> - objtoolopt="${objtoolopt} --orc"
> - fi
> -
> - if is_enabled CONFIG_RETPOLINE; then
> - objtoolopt="${objtoolopt} --retpoline"
> - fi
> -
> - if is_enabled CONFIG_SLS; then
> - objtoolopt="${objtoolopt} --sls"
> - fi
> -
> - if is_enabled CONFIG_STACK_VALIDATION; then
> - objtoolopt="${objtoolopt} --stackval"
> - fi
> -
> - if is_enabled CONFIG_HAVE_STATIC_CALL_INLINE; then
> - objtoolopt="${objtoolopt} --static-call"
> - fi
> -
> - objtoolopt="${objtoolopt} --uaccess"
> - fi
> -
> - if is_enabled CONFIG_NOINSTR_VALIDATION; then
> - objtoolopt="${objtoolopt} --noinstr"
> - fi
> -
> - if [ -n "${objtoolopt}" ]; then
> -
> - if is_enabled CONFIG_GCOV_KERNEL; then
> - objtoolopt="${objtoolopt} --no-unreachable"
> - fi
> -
> - objtoolopt="${objtoolopt} --link"
> -
> - info OBJTOOL ${1}
> - tools/objtool/objtool ${objtoolopt} ${1}
> - fi
> -}
> -
> # Link of vmlinux
> # ${1} - output file
> # ${2}, ${3}, ... - optional extra .o files
> @@ -298,7 +228,6 @@ ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
>
> #link vmlinux.o
^^ While you are at it, change the comment to "# Link of vmlinux.o".
> ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux_o"
> -objtool_link vmlinux.o
>
> # Generate the list of objects in vmlinux
> for f in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
> --
> 2.32.0
>
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