On Tue, Aug 31, 2021 at 04:39:58PM +0900, Masahiro Yamada wrote: > Merge all *.o.symversions in scripts/link-vmlinux.sh instead of > incrementally merging them in the unit of built-in.a or lib.a. > > This is a preparation for further code cleanups. > > The initial patch version was implemented in a shell script, but it > was slow due to the slowness of the 'cat' command [1]. This version > was implemented in Perl. > > [1]: https://lore.kernel.org/lkml/CAK7LNATyNAu6sa-TT9JXy=BXr5d2Q5K-sp-mVXXtJDuJyi6_bA@xxxxxxxxxxxxxx/ > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> My earlier questions about speed here were actually with regard to non-LTO builds. But it sounds like it's not a problem there either. Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > > scripts/Makefile.build | 10 ++------ > scripts/link-vmlinux.sh | 9 ++----- > scripts/merge-symvers.pl | 52 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 56 insertions(+), 15 deletions(-) > create mode 100644 scripts/merge-symvers.pl > > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index afc906cd7256..3ad1b1227371 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -434,11 +434,8 @@ endif > quiet_cmd_ar_builtin = AR $@ > cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs) > > -quiet_cmd_ar_and_symver = AR $@ > - cmd_ar_and_symver = $(cmd_update_lto_symversions); $(cmd_ar_builtin) > - > $(obj)/built-in.a: $(real-obj-y) FORCE > - $(call if_changed,ar_and_symver) > + $(call if_changed,ar_builtin) > > # > # Rule to create modules.order file > @@ -458,11 +455,8 @@ $(obj)/modules.order: $(obj-m) FORCE > # > # Rule to compile a set of .o files into one .a file (with symbol table) > # > -quiet_cmd_ar_lib = AR $@ > - cmd_ar_lib = $(cmd_update_lto_symversions); $(cmd_ar) > - > $(obj)/lib.a: $(lib-y) FORCE > - $(call if_changed,ar_lib) > + $(call if_changed,ar) > > # NOTE: > # Do not replace $(filter %.o,^) with $(real-prereqs). When a single object > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index d74cee5c4326..0cc6a03f2cb1 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -57,13 +57,8 @@ gen_initcalls() > gen_symversions() > { > info GEN .tmp_symversions.lds > - rm -f .tmp_symversions.lds > - > - for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do > - if [ -f ${o}.symversions ]; then > - cat ${o}.symversions >> .tmp_symversions.lds > - fi > - done > + ${PERL} scripts/merge-symvers.pl -a ${AR} -o .tmp_symversions.lds \ > + ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} > } > > # Link of vmlinux.o used for section mismatch analysis > diff --git a/scripts/merge-symvers.pl b/scripts/merge-symvers.pl > new file mode 100644 > index 000000000000..0bd092d24eff > --- /dev/null > +++ b/scripts/merge-symvers.pl > @@ -0,0 +1,52 @@ > +#!/usr/bin/env perl > +# SPDX-License-Identifier: GPL-2.0-only > + > +use autodie; > +use strict; > +use warnings; > +use Getopt::Long 'GetOptions'; > + > +my $ar; > +my $output; > + > +GetOptions( > + 'a|ar=s' => \$ar, > + 'o|output=s' => \$output, > +); > + > +# Collect all objects > +my @objects; > + > +foreach (@ARGV) { > + if (/\.o$/) { > + # Some objects (head-y) are linked to vmlinux directly. > + push(@objects, $_); > + } elsif (/\.a$/) { > + # Most of built-in objects are contained in built-in.a or lib.a. > + # Use 'ar -t' to get the list of the contained objects. > + $_ = `$ar -t $_`; > + push(@objects, split(/\n/)); > + } else { > + die "$_: unknown file type\n"; > + } > +} > + > +open(my $out_fh, '>', "$output"); > + > +foreach (@objects) { > + # The symbol CRCs for foo/bar/baz.o is output to foo/bar/baz.o.symversions > + s/(.*)/$1.symversions/; > + > + if (! -e $_) { > + # .symversions does not exist if the object does not contain > + # EXPORT_SYMBOL at all. Skip it. > + next; > + } > + > + open(my $in_fh, '<', "$_"); > + # Concatenate all the existing *.symversions files. > + print $out_fh do { local $/; <$in_fh> }; > + close $in_fh; > +} > + > +close $out_fh; > -- > 2.30.2 > -- Kees Cook
