kbuild: change scripts/mksysmap into sed script

The previous commit removed the subshell execution from scripts/mksysmap,
which is now simple enough to become a sed script.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/link-vmlinux.sh

@@ -193,7 +193,7 @@ kallsyms_step()
 mksysmap()
 {
 	info NM ${2}
-	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
+	${NM} -n "${1}" | "${srctree}/scripts/mksysmap" > "${2}"
 }
 
 sorttable()

scripts/mksysmap

-#!/bin/sh -x
-# Based on the vmlinux file create the System.map file
+#!/bin/sed -f
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# sed script to filter out symbols that are not needed for System.map,
+# or not suitable for kallsyms. The input should be 'nm -n <file>'.
+#
 # System.map is used by module-init tools and some debugging
 # tools to retrieve the actual addresses of symbols in the kernel.
 #
-# Usage
-# mksysmap vmlinux System.map
-
-
-#####
-# Generate System.map (actual filename passed as second argument)
-# The following refers to the symbol type as per nm(1).
-
 # readprofile starts reading symbols when _stext is found, and
 # continue until it finds a symbol which is not either of 'T', 't',
 # 'W' or 'w'.
 #
-
-${NM} -n ${1} | sed >${2} -e "
 # ---------------------------------------------------------------------------
 # Ignored symbol types
 #
@@ -92,4 +86,3 @@ ${NM} -n ${1} | sed >${2} -e "
 # ppc stub
 /\.long_branch\./d
 /\.plt_branch\./d
-"