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 8083013fc3 ("ld-version: Fix it on Fedora")

 - GNU ld (GNU Binutils) 2.20.1.20100303
   as reported by commit 0d61ed17dd ("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>

MAINTAINERS

@@ -4314,7 +4314,6 @@ C:	irc://chat.freenode.net/clangbuiltlinux
 F:	Documentation/kbuild/llvm.rst
 F:	include/linux/compiler-clang.h
 F:	scripts/clang-tools/
-F:	scripts/lld-version.sh
 K:	\b(?i:clang|llvm)\b
 
 CLEANCACHE API

init/Kconfig

@@ -33,24 +33,29 @@ config GCC_VERSION
 	default $(cc-version) if CC_IS_GCC
 	default 0
 
-config LD_VERSION
-	int
-	default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
-
 config CC_IS_CLANG
 	def_bool $(success,test "$(cc-name)" = Clang)
 
-config LD_IS_LLD
-	def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
-
 config CLANG_VERSION
 	int
 	default $(cc-version) if CC_IS_CLANG
 	default 0
 
+config LD_IS_BFD
+	def_bool $(success,test "$(ld-name)" = BFD)
+
+config LD_VERSION
+	int
+	default $(ld-version) if LD_IS_BFD
+	default 0
+
+config LD_IS_LLD
+	def_bool $(success,test "$(ld-name)" = LLD)
+
 config LLD_VERSION
 	int
-	default $(shell,$(srctree)/scripts/lld-version.sh $(LD))
+	default $(ld-version) if LD_IS_LLD
+	default 0
 
 config CC_CAN_LINK
 	bool

scripts/Kconfig.include

@@ -45,8 +45,11 @@ $(error-if,$(success,test -z "$(cc-info)"),Sorry$(comma) this compiler is not su
 cc-name := $(shell,set -- $(cc-info) && echo $1)
 cc-version := $(shell,set -- $(cc-info) && echo $2)
 
-# Fail if the linker is gold as it's not capable of linking the kernel proper
-$(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supported)
+# Get the linker name, version, and error out if it is not supported.
+ld-info := $(shell,$(srctree)/scripts/ld-version.sh $(LD))
+$(error-if,$(success,test -z "$(ld-info)"),Sorry$(comma) this linker is not supported.)
+ld-name := $(shell,set -- $(ld-info) && echo $1)
+ld-version := $(shell,set -- $(ld-info) && echo $2)
 
 # machine bit flags
 #  $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.

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

scripts/lld-version.sh

@@ -1,20 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-#
-# Usage: $ ./scripts/lld-version.sh ld.lld
-#
-# Print the linker version of `ld.lld' in a 5 or 6-digit form
-# such as `100001' for ld.lld 10.0.1 etc.
-
-linker_string="$($* --version)"
-
-if ! ( echo $linker_string | grep -q LLD ); then
-	echo 0
-	exit 1
-fi
-
-VERSION=$(echo $linker_string | cut -d ' ' -f 2)
-MAJOR=$(echo $VERSION | cut -d . -f 1)
-MINOR=$(echo $VERSION | cut -d . -f 2)
-PATCHLEVEL=$(echo $VERSION | cut -d . -f 3)
-printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL