scripts: Coccinelle script for namespace dependencies.

A script that uses the '<module>.ns_deps' files generated by modpost to
automatically add the required symbol namespace dependencies to each
module.

Usage:
1) Move some symbols to a namespace with EXPORT_SYMBOL_NS() or define
   DEFAULT_SYMBOL_NAMESPACE
2) Run 'make' (or 'make modules') and get warnings about modules not
   importing that namespace.
3) Run 'make nsdeps' to automatically add required import statements
   to said modules.

This makes it easer for subsystem maintainers to introduce and maintain
symbol namespaces into their codebase.

Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>

MAINTAINERS

@@ -11436,6 +11436,11 @@ S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git
 F:	tools/include/nolibc/
 
+NSDEPS
+M:	Matthias Maennich <maennich@google.com>
+S:	Maintained
+F:	scripts/nsdeps
+
 NTB AMD DRIVER
 M:	Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
 L:	linux-ntb@googlegroups.com

Makefile

@@ -1500,6 +1500,9 @@ help:
 	@echo  '  headerdep       - Detect inclusion cycles in headers'
 	@echo  '  coccicheck      - Check with Coccinelle'
 	@echo  ''
+	@echo  'Tools:'
+	@echo  '  nsdeps          - Generate missing symbol namespace dependencies'
+	@echo  ''
 	@echo  'Kernel selftest:'
 	@echo  '  kselftest       - Build and run kernel selftest (run as root)'
 	@echo  '                    Build, install, and boot kernel before'
@@ -1687,6 +1690,15 @@ quiet_cmd_tags = GEN     $@
 tags TAGS cscope gtags: FORCE
 	$(call cmd,tags)
 
+# Script to generate missing namespace dependencies
+# ---------------------------------------------------------------------------
+
+PHONY += nsdeps
+
+nsdeps: modules
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost nsdeps
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/$@
+
 # Scripts to check various things for consistency
 # ---------------------------------------------------------------------------
 

scripts/Makefile.modpost

@@ -56,7 +56,8 @@ MODPOST = scripts/mod/modpost						\
 	$(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS)))	\
 	$(if $(KBUILD_EXTMOD),-o $(modulesymfile))			\
 	$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E)			\
-	$(if $(KBUILD_MODPOST_WARN),-w)
+	$(if $(KBUILD_MODPOST_WARN),-w)					\
+	$(if $(filter nsdeps,$(MAKECMDGOALS)),-d)
 
 ifdef MODPOST_VMLINUX
 
@@ -134,6 +135,7 @@ $(modules): %.ko :%.o %.mod.o FORCE
 
 targets += $(modules)
 
+nsdeps: __modpost
 
 # Add FORCE to the prequisites of a target to force it to be always rebuilt.
 # ---------------------------------------------------------------------------

scripts/coccinelle/misc/add_namespace.cocci

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+/// Adds missing MODULE_IMPORT_NS statements to source files
+///
+/// This script is usually called from scripts/nsdeps with -D ns=<namespace> to
+/// add a missing namespace tag to a module source file.
+///
+
+@has_ns_import@
+declarer name MODULE_IMPORT_NS;
+identifier virtual.ns;
+@@
+MODULE_IMPORT_NS(ns);
+
+// Add missing imports, but only adjacent to a MODULE_LICENSE statement.
+// That ensures we are adding it only to the main module source file.
+@do_import depends on !has_ns_import@
+declarer name MODULE_LICENSE;
+expression license;
+identifier virtual.ns;
+@@
+MODULE_LICENSE(license);
++ MODULE_IMPORT_NS(ns);

scripts/nsdeps

@@ -0,0 +1,58 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Linux kernel symbol namespace import generator
+#
+# This script requires a minimum spatch version.
+SPATCH_REQ_VERSION="1.0.4"
+
+DIR="$(dirname $(readlink -f $0))/.."
+SPATCH="`which ${SPATCH:=spatch}`"
+if [ ! -x "$SPATCH" ]; then
+	echo 'spatch is part of the Coccinelle project and is available at http://coccinelle.lip6.fr/'
+	exit 1
+fi
+
+SPATCH_REQ_VERSION_NUM=$(echo $SPATCH_REQ_VERSION | ${DIR}/scripts/ld-version.sh)
+SPATCH_VERSION=$($SPATCH --version | head -1 | awk '{print $3}')
+SPATCH_VERSION_NUM=$(echo $SPATCH_VERSION | ${DIR}/scripts/ld-version.sh)
+
+if [ "$SPATCH_VERSION_NUM" -lt "$SPATCH_REQ_VERSION_NUM" ] ; then
+	echo "spatch needs to be version $SPATCH_REQ_VERSION or higher"
+	exit 1
+fi
+
+generate_deps_for_ns() {
+	$SPATCH --very-quiet --in-place --sp-file \
+		$srctree/scripts/coccinelle/misc/add_namespace.cocci -D ns=$1 $2
+}
+
+generate_deps() {
+	local mod_name=`basename $@ .ko`
+	local mod_file=`echo $@ | sed -e 's/\.ko/\.mod/'`
+	local ns_deps_file=`echo $@ | sed -e 's/\.ko/\.ns_deps/'`
+	if [ ! -f "$ns_deps_file" ]; then return; fi
+	local mod_source_files=`cat $mod_file | sed -n 1p                      \
+					      | sed -e 's/\.o/\.c/g'           \
+					      | sed "s/[^ ]* */${srctree}\/&/g"`
+	for ns in `cat $ns_deps_file`; do
+		echo "Adding namespace $ns to module $mod_name (if needed)."
+		generate_deps_for_ns $ns $mod_source_files
+		# sort the imports
+		for source_file in $mod_source_files; do
+			sed '/MODULE_IMPORT_NS/Q' $source_file > ${source_file}.tmp
+			offset=$(wc -l ${source_file}.tmp | awk '{print $1;}')
+			cat $source_file | grep MODULE_IMPORT_NS | sort -u >> ${source_file}.tmp
+			tail -n +$((offset +1)) ${source_file} | grep -v MODULE_IMPORT_NS >> ${source_file}.tmp
+			if ! diff -q ${source_file} ${source_file}.tmp; then
+				mv ${source_file}.tmp ${source_file}
+			else
+				rm ${source_file}.tmp
+			fi
+		done
+	done
+}
+
+for f in `cat $objtree/modules.order`; do
+	generate_deps $f
+done
+