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author | Masahiro Yamada <masahiroy@kernel.org> | 2022-05-05 10:22:35 +0300 |
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committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-05-11 15:46:39 +0300 |
commit | 78e9e56af3858bf2c52c065daa6c8bee0d72048c (patch) | |
tree | 77732a7f52cdd495fae4ef92a1fce5efd326b913 /scripts/Makefile.build | |
parent | e493f472752000968f5b30aac10391288cfbf5b1 (diff) | |
download | linux-78e9e56af3858bf2c52c065daa6c8bee0d72048c.tar.xz |
kbuild: record symbol versions in *.cmd files
When CONFIG_MODVERSIONS=y, the output from genksyms is saved in
separate *.symversions files, and will be used much later when
CONFIG_LTO_CLANG=y because it is impossible to update LLVM bit code
here.
This approach is not robust because:
- *.symversions may or may not exist. If *.symversions does not
exist, we never know if it is missing for legitimate reason
(i.e. no EXPORT_SYMBOL) or something bad has happened (for
example, the user accidentally deleted it). Once it occurs,
it is not self-healing because *.symversions is generated
as a side effect.
- stale (i.e. invalid) *.symversions might be picked up if an
object is generated in a non-ordinary way, and corresponding
*.symversions (, which was generated by old builds) just happen
to exist.
A more robust approach is to save symbol versions in *.cmd files
because:
- *.cmd always exists (if the object is generated by if_changed
rule or friends). Even if the user accidentally deletes it,
it will be regenerated in the next build.
- *.cmd is always re-generated when the object is updated. This
avoid stale version information being picked up.
I will remove *.symversions later.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r-- | scripts/Makefile.build | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f6a506318795..a1023868775f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -171,10 +171,17 @@ ifdef CONFIG_MODVERSIONS # Generate .o.symversions files for each .o with exported symbols, and link these # to the kernel and/or modules at the end. + +genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).* +genksyms_format_normal := __crc_\(.*\) = \(.*\); +genksyms_format := $(if $(CONFIG_MODULE_REL_CRCS),$(genksyms_format_rel_crc),$(genksyms_format_normal)) + gen_symversions = \ if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \ $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ > $@.symversions; \ + sed -n 's/$(genksyms_format)/$(pound)SYMVER \1 \2/p' $@.symversions \ + >> $(dot-target).cmd; \ else \ rm -f $@.symversions; \ fi |