Merge tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:
 "Build system:

   - add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
     fixed set of export symbols for Generic Kernel Image (GKI)

   - allow to run 'make dt_binding_check' without .config

   - use full schema for checking DT examples in *.yaml files

   - make modpost fail for missing MODULE_IMPORT_NS(), which makes more
     sense because we know the produced modules are never loadable

   - Remove unused 'AS' variable

  Kconfig:

   - sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
     files

   - relax the 'imply' behavior so that symbols implied by 'y' can
     become 'm'

   - make 'imply' obey 'depends on' in order to make 'imply' really weak

  Misc:

   - add documentation on building the kernel with Clang/LLVM

   - revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()

   - fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n

   - various script and Makefile cleanups"

* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  Makefile: Update kselftest help information
  kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
  kbuild: add outputmakefile to no-dot-config-targets
  kbuild: remove AS variable
  net: wan: wanxl: refactor the firmware rebuild rule
  net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
  net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
  kbuild: add comment about grouped target
  kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
  kconfig: remove unused variable in qconf.cc
  sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
  kbuild: refactor Makefile.dtbinst more
  kbuild: compute the dtbs_install destination more simply
  Makefile: disallow data races on gcc-10 as well
  kconfig: make 'imply' obey the direct dependency
  kconfig: allow symbols implied by y to become m
  net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
  modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
  modpost: rework and consolidate logging interface
  kbuild: allow to run dt_binding_check without kernel configuration
  ...

1 files changed, 52 insertions, 0 deletions

diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
new file mode 100755
index 000000000000..16c0b2ddaa4c
--- /dev/null
+++ b/scripts/gen_autoksyms.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+
+# Create an autoksyms.h header file from the list of all module's needed symbols
+# as recorded on the second line of *.mod files and the user-provided symbol
+# whitelist.
+
+set -e
+
+output_file="$1"
+
+# Use "make V=1" to debug this script.
+case "$KBUILD_VERBOSE" in
+*1*)
+	set -x
+	;;
+esac
+
+# We need access to CONFIG_ symbols
+. include/config/auto.conf
+
+ksym_wl=/dev/null
+if [ -n "$CONFIG_UNUSED_KSYMS_WHITELIST" ]; then
+	# Use 'eval' to expand the whitelist path and check if it is relative
+	eval ksym_wl="$CONFIG_UNUSED_KSYMS_WHITELIST"
+	[ "${ksym_wl}" != "${ksym_wl#/}" ] || ksym_wl="$abs_srctree/$ksym_wl"
+	if [ ! -f "$ksym_wl" ] || [ ! -r "$ksym_wl" ]; then
+		echo "ERROR: '$ksym_wl' whitelist file not found" >&2
+		exit 1
+	fi
+fi
+
+# Generate a new ksym list file with symbols needed by the current
+# set of modules.
+cat > "$output_file" << EOT
+/*
+ * Automatically generated file; DO NOT EDIT.
+ */
+
+EOT
+
+[ -f modules.order ] && modlist=modules.order || modlist=/dev/null
+sed 's/ko$/mod/' $modlist |
+xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
+cat - "$ksym_wl" |
+sort -u |
+sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$output_file"
+
+# Special case for modversions (see modpost.c)
+if [ -n "$CONFIG_MODVERSIONS" ]; then
+	echo "#define __KSYM_module_layout 1" >> "$output_file"
+fi