kbuild: check the minimum linker version in Kconfig

Unify the two scripts/ld-version.sh and scripts/lld-version.sh, and
check the minimum linker version like scripts/cc-version.sh did.

I tested this script for some corner cases reported in the past:

 - GNU ld version 2.25-15.fc23
   as reported by commit 8083013fc320 ("ld-version: Fix it on Fedora")

 - GNU ld (GNU Binutils) 2.20.1.20100303
   as reported by commit 0d61ed17dd30 ("ld-version: Drop the 4th and
   5th version components")

This script show an error message if the linker is too old:

  $ make LD=ld.lld-9
    SYNC    include/config/auto.conf
  ***
  *** Linker is too old.
  ***   Your LLD version:    9.0.1
  ***   Minimum LLD version: 10.0.1
  ***
  scripts/Kconfig.include:50: Sorry, this linker is not supported.
  make[2]: *** [scripts/kconfig/Makefile:71: syncconfig] Error 1
  make[1]: *** [Makefile:600: syncconfig] Error 2
  make: *** [Makefile:708: include/config/auto.conf] Error 2

I also moved the check for gold to this script, so gold is still rejected:

  $ make LD=gold
    SYNC    include/config/auto.conf
  gold linker is not supported as it is not capable of linking the kernel proper.
  scripts/Kconfig.include:50: Sorry, this linker is not supported.
  make[2]: *** [scripts/kconfig/Makefile:71: syncconfig] Error 1
  make[1]: *** [Makefile:600: syncconfig] Error 2
  make: *** [Makefile:708: include/config/auto.conf] Error 2

Thanks to David Laight for suggesting shell script improvements.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>

1 files changed, 72 insertions, 10 deletions

diff --git a/scripts/ld-version.sh b/scripts/ld-version.sh
index 0f8a2c0f9502..a463273509b5 100755
--- a/scripts/ld-version.sh
+++ b/scripts/ld-version.sh
@@ -1,11 +1,73 @@
-#!/usr/bin/awk -f
+#!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
-# extract linker version number from stdin and turn into single number
-	{
-	gsub(".*\\)", "");
-	gsub(".*version ", "");
-	gsub("-.*", "");
-	split($1,a, ".");
-	print a[1]*10000 + a[2]*100 + a[3];
-	exit
-	}
+#
+# Print the linker name and its version in a 5 or 6-digit form.
+# Also, perform the minimum version check.
+
+set -e
+
+# When you raise the minimum linker version, please update
+# Documentation/process/changes.rst as well.
+bfd_min_version=2.23.0
+lld_min_version=10.0.1
+
+# Convert the version string x.y.z to a canonical 5 or 6-digit form.
+get_canonical_version()
+{
+	IFS=.
+	set -- $1
+
+	# If the 2nd or 3rd field is missing, fill it with a zero.
+	#
+	# The 4th field, if present, is ignored.
+	# This occurs in development snapshots as in 2.35.1.20201116
+	echo $((10000 * $1 + 100 * ${2:-0} + ${3:-0}))
+}
+
+orig_args="$@"
+
+# Get the first line of the --version output.
+IFS='
+'
+set -- $("$@" --version)
+
+# Split the line on spaces.
+IFS=' '
+set -- $1
+
+if [ "$1" = GNU -a "$2" = ld ]; then
+	shift $(($# - 1))
+	version=$1
+	min_version=$bfd_min_version
+	name=BFD
+	disp_name="GNU ld"
+elif [ "$1" = GNU -a "$2" = gold ]; then
+	echo "gold linker is not supported as it is not capable of linking the kernel proper." >&2
+	exit 1
+elif [ "$1" = LLD ]; then
+	version=$2
+	min_version=$lld_min_version
+	name=LLD
+	disp_name=LLD
+else
+	echo "$orig_args: unknown linker" >&2
+	exit 1
+fi
+
+# Some distributions append a package release number, as in 2.34-4.fc32
+# Trim the hyphen and any characters that follow.
+version=${version%-*}
+
+cversion=$(get_canonical_version $version)
+min_cversion=$(get_canonical_version $min_version)
+
+if [ "$cversion" -lt "$min_cversion" ]; then
+	echo >&2 "***"
+	echo >&2 "*** Linker is too old."
+	echo >&2 "***   Your $disp_name version:    $version"
+	echo >&2 "***   Minimum $disp_name version: $min_version"
+	echo >&2 "***"
+	exit 1
+fi
+
+echo $name $cversion