Merge tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - remove unneeded asm headers from hexagon, ia64

 - add 'dir-pkg' target, which works like 'tar-pkg' but skips archiving

 - add 'helpnewconfig' target, which shows help for new CONFIG options

 - support 'make nsdeps' for external modules

 - make rebuilds faster by deleting $(wildcard $^) checks

 - remove compile tests for kernel-space headers

 - refactor modpost to simplify modversion handling

 - make single target builds faster

 - optimize and clean up scripts/kallsyms.c

 - refactor various Makefiles and scripts

* tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (59 commits)
  MAINTAINERS: update Kbuild/Kconfig maintainer's email address
  scripts/kallsyms: remove redundant initializers
  scripts/kallsyms: put check_symbol_range() calls close together
  scripts/kallsyms: make check_symbol_range() void function
  scripts/kallsyms: move ignored symbol types to is_ignored_symbol()
  scripts/kallsyms: move more patterns to the ignored_prefixes array
  scripts/kallsyms: skip ignored symbols very early
  scripts/kallsyms: add const qualifiers where possible
  scripts/kallsyms: make find_token() return (unsigned char *)
  scripts/kallsyms: replace prefix_underscores_count() with strspn()
  scripts/kallsyms: add sym_name() to mitigate cast ugliness
  scripts/kallsyms: remove unneeded length check for prefix matching
  scripts/kallsyms: remove redundant is_arm_mapping_symbol()
  scripts/kallsyms: set relative_base more effectively
  scripts/kallsyms: shrink table before sorting it
  scripts/kallsyms: fix definitely-lost memory leak
  scripts/kallsyms: remove unneeded #ifndef ARRAY_SIZE
  kbuild: make single target builds even faster
  modpost: respect the previous export when 'exported twice' is warned
  modpost: do not set ->preloaded for symbols from Module.symvers
  ...

kernel/Makefile

@@ -130,7 +130,7 @@ $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
 $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz
 
 quiet_cmd_genikh = CHK     $(obj)/kheaders_data.tar.xz
-      cmd_genikh = $(BASH) $(srctree)/kernel/gen_kheaders.sh $@
+      cmd_genikh = $(CONFIG_SHELL) $(srctree)/kernel/gen_kheaders.sh $@
 $(obj)/kheaders_data.tar.xz: FORCE
 	$(call cmd,genikh)
 

kernel/gen_kheaders.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
 # This script generates an archive consisting of kernel headers
@@ -21,30 +21,38 @@ arch/$SRCARCH/include/
 # Uncomment it for debugging.
 # if [ ! -f /tmp/iter ]; then iter=1; echo 1 > /tmp/iter;
 # else iter=$(($(cat /tmp/iter) + 1)); echo $iter > /tmp/iter; fi
-# find $src_file_list -name "*.h" | xargs ls -l > /tmp/src-ls-$iter
-# find $obj_file_list -name "*.h" | xargs ls -l > /tmp/obj-ls-$iter
+# find $all_dirs -name "*.h" | xargs ls -l > /tmp/ls-$iter
+
+all_dirs=
+if [ "$building_out_of_srctree" ]; then
+	for d in $dir_list; do
+		all_dirs="$all_dirs $srctree/$d"
+	done
+fi
+all_dirs="$all_dirs $dir_list"
 
 # include/generated/compile.h is ignored because it is touched even when none
-# of the source files changed. This causes pointless regeneration, so let us
-# ignore them for md5 calculation.
-pushd $srctree > /dev/null
-src_files_md5="$(find $dir_list -name "*.h"			   |
-		grep -v "include/generated/compile.h"		   |
-		grep -v "include/generated/autoconf.h"		   |
-		xargs ls -l | md5sum | cut -d ' ' -f1)"
-popd > /dev/null
-obj_files_md5="$(find $dir_list -name "*.h"			   |
-		grep -v "include/generated/compile.h"		   |
-		grep -v "include/generated/autoconf.h"		   |
+# of the source files changed.
+#
+# When Kconfig regenerates include/generated/autoconf.h, its timestamp is
+# updated, but the contents might be still the same. When any CONFIG option is
+# changed, Kconfig touches the corresponding timestamp file include/config/*.h.
+# Hence, the md5sum detects the configuration change anyway. We do not need to
+# check include/generated/autoconf.h explicitly.
+#
+# Ignore them for md5 calculation to avoid pointless regeneration.
+headers_md5="$(find $all_dirs -name "*.h"			|
+		grep -v "include/generated/compile.h"	|
+		grep -v "include/generated/autoconf.h"	|
 		xargs ls -l | md5sum | cut -d ' ' -f1)"
+
 # Any changes to this script will also cause a rebuild of the archive.
 this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"
 if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
 if [ -f kernel/kheaders.md5 ] &&
-	[ "$(cat kernel/kheaders.md5|head -1)" == "$src_files_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|head -2|tail -1)" == "$obj_files_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|head -3|tail -1)" == "$this_file_md5" ] &&
-	[ "$(cat kernel/kheaders.md5|tail -1)" == "$tarfile_md5" ]; then
+	[ "$(head -n 1 kernel/kheaders.md5)" = "$headers_md5" ] &&
+	[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
+	[ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then
 		exit
 fi
 
@@ -55,14 +63,17 @@ fi
 rm -rf $cpio_dir
 mkdir $cpio_dir
 
-pushd $srctree > /dev/null
-for f in $dir_list;
-	do find "$f" -name "*.h";
-done | cpio --quiet -pd $cpio_dir
-popd > /dev/null
+if [ "$building_out_of_srctree" ]; then
+	(
+		cd $srctree
+		for f in $dir_list
+			do find "$f" -name "*.h";
+		done | cpio --quiet -pd $cpio_dir
+	)
+fi
 
-# The second CPIO can complain if files already exist which can
-# happen with out of tree builds. Just silence CPIO for now.
+# The second CPIO can complain if files already exist which can happen with out
+# of tree builds having stale headers in srctree. Just silence CPIO for now.
 for f in $dir_list;
 	do find "$f" -name "*.h";
 done | cpio --quiet -pd $cpio_dir >/dev/null 2>&1
@@ -79,8 +90,7 @@ find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \
     --owner=0 --group=0 --numeric-owner --no-recursion \
     -Jcf $tarfile -C $cpio_dir/ -T - > /dev/null
 
-echo "$src_files_md5" >  kernel/kheaders.md5
-echo "$obj_files_md5" >> kernel/kheaders.md5
+echo $headers_md5 > kernel/kheaders.md5
 echo "$this_file_md5" >> kernel/kheaders.md5
 echo "$(md5sum $tarfile | cut -d ' ' -f1)" >> kernel/kheaders.md5