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From: Masahiro Yamada <masahiroy@kernel.org>
To: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH v2 19/26] kbuild: embed symbol versions at final link of vmlinux or modules
Date: Tue, 3 May 2022 11:55:11 +0900	[thread overview]
Message-ID: <CAK7LNASzBse=oPA2u4dMJoF9VSJ492K+s=d5Yyn4Aw0dJgu03A@mail.gmail.com> (raw)
In-Reply-To: <20220501084032.1025918-20-masahiroy@kernel.org>

On Sun, May 1, 2022 at 5:42 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Do not update objects with version CRCs while the directory descending.
>
> Do it at the final link stage.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>


As 0-day bot reported, this does not work for CONFIG_MODULE_REL_CRCS.

I will send v3.


> ---
>
> (no changes since v1)
>
>  scripts/Makefile.build    | 22 +++-------------------
>  scripts/Makefile.modfinal |  3 ++-
>  scripts/link-vmlinux.sh   |  4 +++-
>  3 files changed, 8 insertions(+), 21 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index a1023868775f..cec17b28de42 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -162,15 +162,9 @@ ifdef CONFIG_MODVERSIONS
>  # o if <file>.o doesn't contain a __ksymtab version, i.e. does
>  #   not export symbols, it's done.
>  # o otherwise, we calculate symbol versions using the good old
> -#   genksyms on the preprocessed source and postprocess them in a way
> -#   that they are usable as a linker script
> -# o generate .tmp_<file>.o from <file>.o using the linker to
> -#   replace the unresolved symbols __crc_exported_symbol with
> -#   the actual value of the checksum generated by genksyms
> -# o remove .tmp_<file>.o to <file>.o
> -
> -# Generate .o.symversions files for each .o with exported symbols, and link these
> -# to the kernel and/or modules at the end.
> +#   genksyms on the preprocessed source and dump them into the .cmd file.
> +# o modpost will extract versions from the .cmd file and create linker
> +#   scripts used to link the kernel and/or modules.
>
>  genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).*
>  genksyms_format_normal := __crc_\(.*\) = \(.*\);
> @@ -188,12 +182,6 @@ gen_symversions =                                                          \
>
>  cmd_gen_symversions_c =        $(call gen_symversions,c)
>
> -cmd_modversions =                                                              \
> -       if [ -r $@.symversions ]; then                                          \
> -               $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
> -                       -T $@.symversions;                                      \
> -               mv -f $(@D)/.tmp_$(@F) $@;                                      \
> -       fi
>  endif
>
>  ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
> @@ -273,7 +261,6 @@ define rule_cc_o_c
>         $(call cmd,checkdoc)
>         $(call cmd,gen_objtooldep)
>         $(call cmd,gen_symversions_c)
> -       $(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
>         $(call cmd,record_mcount)
>  endef
>
> @@ -282,7 +269,6 @@ define rule_as_o_S
>         $(call cmd,gen_ksymdeps)
>         $(call cmd,gen_objtooldep)
>         $(call cmd,gen_symversions_S)
> -       $(call cmd,modversions)
>  endef
>
>  # Built-in and composite module parts
> @@ -296,8 +282,6 @@ ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
>  quiet_cmd_cc_prelink_modules = LD [M]  $@
>        cmd_cc_prelink_modules =                                         \
>         $(LD) $(ld_flags) -r -o $@                                      \
> -               $(shell [ -s $(@:.prelink.o=.o.symversions) ] &&                \
> -                       echo -T $(@:.prelink.o=.o.symversions))         \
>                 --whole-archive $(filter-out FORCE,$^)                  \
>                 $(cmd_objtool)
>
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index 7f39599e9fae..d429e3f9ae1d 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -34,6 +34,7 @@ quiet_cmd_ld_ko_o = LD [M]  $@
>        cmd_ld_ko_o +=                                                   \
>         $(LD) -r $(KBUILD_LDFLAGS)                                      \
>                 $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE)              \
> +               $(addprefix -T, $(filter %.symver.lds, $(real-prereqs)))\
>                 -T scripts/module.lds -o $@ $(filter %.o, $^);          \
>         $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
>
> @@ -56,7 +57,7 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check),      \
>
>
>  # Re-generate module BTFs if either module's .ko or vmlinux changed
> -$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE
> +$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o $(if $(CONFIG_MODVERSIONS), %.symver.lds) scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE
>         +$(call if_changed_except,ld_ko_o,vmlinux)
>  ifdef CONFIG_DEBUG_INFO_BTF_MODULES
>         +$(if $(newer-prereqs),$(call cmd,btf_ko))
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index eceb3ee7ec06..8da5c0182665 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -90,7 +90,6 @@ modpost_link()
>
>                 if is_enabled CONFIG_MODVERSIONS; then
>                         gen_symversions
> -                       lds="${lds} -T .tmp_symversions.lds"
>                 fi
>
>                 # This might take a while, so indicate that we're doing
> @@ -196,6 +195,9 @@ vmlinux_link()
>         fi
>
>         ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
> +       if is_enabled CONFIG_MODVERSIONS; then
> +               ldflags="${ldflags} ${wl}--script=vmlinux.symver.lds"
> +       fi
>
>         # The kallsyms linking does not need debug symbols included.
>         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> --
> 2.32.0
>


-- 
Best Regards
Masahiro Yamada

  reply	other threads:[~2022-05-03  2:56 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-01  8:40 [PATCH v2 00/26] kbuild: yet another series of cleanups (modpost and LTO) Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 01/26] modpost: use bool type where appropriate Masahiro Yamada
2022-05-03 21:43   ` Nick Desaulniers
2022-05-04  5:47     ` Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 02/26] modpost: change mod->gpl_compatible to bool type Masahiro Yamada
2022-05-03 21:45   ` Nick Desaulniers
2022-05-01  8:40 ` [PATCH v2 03/26] modpost: import include/linux/list.h Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 04/26] modpost: traverse modules in order Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 05/26] modpost: add sym_add_unresolved() helper Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 06/26] modpost: traverse unresolved symbols in order Masahiro Yamada
2022-05-03 21:49   ` Nick Desaulniers
2022-05-01  8:40 ` [PATCH v2 07/26] modpost: use doubly linked list for dump_lists Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 08/26] modpost: traverse the namespace_list in order Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 09/26] modpost: dump Module.symvers in the same order of modules.order Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 10/26] modpost: move static EXPORT_SYMBOL check to check_exports() Masahiro Yamada
2022-05-03 21:54   ` Nick Desaulniers
2022-05-01  8:40 ` [PATCH v2 11/26] modpost: make multiple export error Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 12/26] modpost: make sym_add_exported() always allocate a new symbol Masahiro Yamada
2022-05-03 21:56   ` Nick Desaulniers
2022-05-01  8:40 ` [PATCH v2 13/26] modpost: split new_symbol() to symbol allocation and hash table addition Masahiro Yamada
2022-05-03 22:00   ` Nick Desaulniers
2022-05-01  8:40 ` [PATCH v2 14/26] modpost: mitigate false-negatives for static EXPORT_SYMBOL checks Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 15/26] kbuild: record symbol versions in *.cmd files Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 16/26] kbuild: generate a list of objects in vmlinux Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 17/26] modpost: extract symbol versions from *.cmd files Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 18/26] modpost: generate linker script to collect symbol versions Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 19/26] kbuild: embed symbol versions at final link of vmlinux or modules Masahiro Yamada
2022-05-03  2:55   ` Masahiro Yamada [this message]
2022-05-01  8:40 ` [PATCH v2 20/26] kbuild: stop merging *.symversions Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 21/26] genksyms: adjust the output format for .cmd files Masahiro Yamada
2022-05-04 20:22   ` Nicolas Schier
2022-05-05 13:47     ` Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 22/26] kbuild: do not create *.prelink.o for Clang LTO or IBT Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 23/26] kbuild: make built-in.a rule robust against too long argument error Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 24/26] kbuild: make *.mod " Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 25/26] modpost: simplify the ->is_static initialization Masahiro Yamada
2022-05-01  8:40 ` [PATCH v2 26/26] modpost: use hlist for hash table implementation Masahiro Yamada
2022-05-01 12:23 ` [PATCH v2 00/26] kbuild: yet another series of cleanups (modpost and LTO) Masahiro Yamada
2022-05-05  6:55 ` Masahiro Yamada

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