[PATCH] scripts/recordmcount.pl: Remove check_objcopy() and $can_use_local

[Nathan Chancellor]

When building ARCH=riscv allmodconfig with llvm-objcopy, the objcopy
version warning from this script appears:

WARNING: could not find objcopy version or version is less than 2.17.
Local function references are disabled.

The check_objcopy() function in scripts/recordmcount.pl is set up to
parse GNU objcopy's version string, not llvm-objcopy's, which triggers
the warning.

Commit 799c43415442 ("kbuild: thin archives make default for all archs")
made binutils 2.20 mandatory and commit ba64beb17493 ("kbuild: check the
minimum assembler version in Kconfig") enforces this at configuration
time so just remove check_objcopy() and $can_use_local instead, assuming
--globalize-symbol is always available.

llvm-objcopy has supported --globalize-symbol since LLVM 7.0.0 in 2018
and the minimum version for building the kernel with LLVM is 10.0.1 so
there is no issue introduced:

https://github.com/llvm/llvm-project/commit/ee5be798dae30d5f9414b01f76ff807edbc881aa

Signed-off-by: Nathan Chancellor <nat...@kernel.org>
---
Makefile | 1 -
scripts/recordmcount.pl | 40 ----------------------------------------
2 files changed, 41 deletions(-)

diff --git a/Makefile b/Makefile
index 27a072cffcb9..b6ee64dd435e 100644
--- a/Makefile
+++ b/Makefile
@@ -546,7 +546,6 @@ export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
PHONY += scripts_basic
scripts_basic:
$(Q)$(MAKE) $(build)=scripts/basic
- $(Q)rm -f .tmp_quiet_recordmcount

PHONY += outputmakefile
ifdef building_out_of_srctree
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index c17e48020ec3..8f6b13ae46bf 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -173,39 +173,6 @@ my $mcount_regex; # Find the call site to mcount (return offset)
my $mcount_adjust; # Address adjustment to mcount offset
my $alignment; # The .align value to use for $mcount_section
my $section_type; # Section header plus possible alignment command
-my $can_use_local = 0; # If we can use local function references
-
-# Shut up recordmcount if user has older objcopy
-my $quiet_recordmcount = ".tmp_quiet_recordmcount";
-my $print_warning = 1;
-$print_warning = 0 if ( -f $quiet_recordmcount);
-
-##
-# check_objcopy - whether objcopy supports --globalize-symbols
-#
-# --globalize-symbols came out in 2.17, we must test the version
-# of objcopy, and if it is less than 2.17, then we can not
-# record local functions.
-sub check_objcopy
-{
- open (IN, "$objcopy --version |") or die "error running $objcopy";
- while (<IN>) {
- if (/objcopy.*\s(\d+)\.(\d+)/) {
- $can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17));
- last;
- }
- }
- close (IN);
-
- if (!$can_use_local && $print_warning) {
- print STDERR "WARNING: could not find objcopy version or version " .
- "is less than 2.17.\n" .
- "\tLocal function references are disabled.\n";
- open (QUIET, ">$quiet_recordmcount");
- printf QUIET "Disables the warning from recordmcount.pl\n";
- close QUIET;
- }
-}

if ($arch =~ /(x86(_64)?)|(i386)/) {
if ($bits == 64) {
@@ -434,8 +401,6 @@ if ($filename =~ m,^(.*)(\.\S),) {
my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";

-check_objcopy();
-
#
# Step 1: find all the local (static functions) and weak symbols.
# 't' is local, 'w/W' is weak
@@ -473,11 +438,6 @@ sub update_funcs

# is this function static? If so, note this fact.
if (defined $locals{$ref_func}) {
-
- # only use locals if objcopy supports globalize-symbols
- if (!$can_use_local) {
- return;
- }
$convert{$ref_func} = 1;
}


base-commit: c500bee1c5b2f1d59b1081ac879d73268ab0ff17
--
2.32.0.264.g75ae10bc75

[Nick Desaulniers]

On Mon, Aug 2, 2021 at 2:05 PM Nathan Chancellor <nat...@kernel.org> wrote:
>
> When building ARCH=riscv allmodconfig with llvm-objcopy, the objcopy
> version warning from this script appears:
>
> WARNING: could not find objcopy version or version is less than 2.17.
> Local function references are disabled.
>
> The check_objcopy() function in scripts/recordmcount.pl is set up to
> parse GNU objcopy's version string, not llvm-objcopy's, which triggers
> the warning.
>
> Commit 799c43415442 ("kbuild: thin archives make default for all archs")
> made binutils 2.20 mandatory and commit ba64beb17493 ("kbuild: check the
> minimum assembler version in Kconfig") enforces this at configuration
> time so just remove check_objcopy() and $can_use_local instead, assuming
> --globalize-symbol is always available.
>
> llvm-objcopy has supported --globalize-symbol since LLVM 7.0.0 in 2018
> and the minimum version for building the kernel with LLVM is 10.0.1 so
> there is no issue introduced:
>
> https://github.com/llvm/llvm-project/commit/ee5be798dae30d5f9414b01f76ff807edbc881aa

^ should this be a Link: tag?

Reviewed-by: Nick Desaulniers <ndesau...@google.com>

--
Thanks,
~Nick Desaulniers