[PATCH 4/4] KBUILD: export-symbol usage report generator

[linuxram@us.ibm.com (Ram Pai)]

From: Ram Pai <linuxram@us.ibm.com>

The following patch provides the ability to generate a report of
     (1) All the exported symbols and their in-kernel-module usage count
     (2) For each module, lists the modules and their exported symbols, on
                which it depends.

The report generation is integrated in the build process.
'make exportcheck' prints out the report.
'make exportcheck EXPORTFILE=Documentation/export_report.txt'
        generates the report in the file Documentation/export_report.txt

NOTE: the same report can also be generated by executing
	perl scripts/export_report

Signed-off-by: Ram Pai <linuxram@us.ibm.com>

 Makefile                 |   16 ++++-
 scripts/Makefile.modpost |    7 ++
 scripts/export_report.pl |  148 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+), 1 deletion(-)

Index: linux-2.6.17-rc3/scripts/Makefile.modpost
===================================================================
--- linux-2.6.17-rc3.orig/scripts/Makefile.modpost
+++ linux-2.6.17-rc3/scripts/Makefile.modpost
@@ -60,9 +60,16 @@ quiet_cmd_modpost = MODPOST
 	$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
 	$(filter-out FORCE,$^)
 
+quiet_cmd_importfile = IMPORT_EXTRACT
+      cmd_importfile =  perl $(objtree)/scripts/export_report.pl  \
+	-k $(kernelsymfile) \
+	$(if $(KBUILD_EXPORT_REPORT:1=),-o $(KBUILD_EXPORT_REPORT),) \
+	-f $(patsubst %.o,%.mod.c,$(filter-out vmlinux FORCE, $^))
+
 PHONY += __modpost
 __modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE
 	$(call cmd,modpost)
+	$(if $(KBUILD_EXPORT_REPORT), $(call cmd,importfile))
 
 # Declare generated files as targets for modpost
 $(symverfile):         __modpost ;
Index: linux-2.6.17-rc3/scripts/export_report.pl
===================================================================
--- /dev/null
+++ linux-2.6.17-rc3/scripts/export_report.pl
@@ -0,0 +1,148 @@
+#!/usr/bin/perl -w
+#
+# (C) Copyright IBM Corporation 2006.
+#	Released under GPL v2.
+#	Author : Ram Pai (linuxram@us.ibm.com)
+#
+# Usage: export_report.pl -k Module.symvers [-o report_file ] *.mod.c
+#
+
+use Getopt::Std;
+use strict;
+
+sub numerically {
+	my $no1 = (split /\s+/, $a)[1];
+	my $no2 = (split /\s+/, $b)[1];
+	return $no1 <=> $no2;
+}
+
+sub alphabetically {
+	my ($module1, $value1) = @{$a};
+	my ($module2, $value2) = @{$b};
+	return $value1 <=> $value2 || $module2 cmp $module1;
+}
+
+sub print_depends_on {
+	my ($href) = @_;
+	print "\n";
+	while (my ($mod, $list) = each %$href) {
+		print "\t$mod:\n";
+		foreach my $sym (sort numerically @{$list}) {
+			my ($symbol, $no) = split /\s+/, $sym;
+			printf("\t\t%-25s\t%-25d\n", $symbol, $no);
+		}
+		print "\n";
+	}
+	print "\n";
+	print "~"x80 , "\n";
+}
+
+sub usage {
+        die "Usage: @_ -h -k Module.symvers  [ -o outputfile ]  -f  all the .mod.c files \n";
+}
+
+sub collectcfiles {
+        my @file = `cat .tmp_versions/*.mod | grep '.*\.ko\$'`;
+        @file = grep {s/\.ko/.mod.c/} @file;
+        return @file;
+}
+
+my (%SYMBOL, %MODULE, %opt, @allcfiles);
+
+if (not getopts('hk:o:f',\%opt) or defined $opt{'h'}) {
+        usage($0);
+}
+
+if (defined $opt{'f'}) {
+	@allcfiles = @ARGV;
+} else {
+	@allcfiles = collectcfiles();
+}
+
+if (not defined $opt{'k'}) {
+	$opt{'k'} = "Module.symvers";
+}
+
+unless (open(MODULE_SYMVERS, $opt{'k'})) {
+	die "Sorry, cannot open $opt{'k'}: $!\n";
+}
+
+
+if (defined $opt{'o'}) {
+	unless (open(OUTPUT_HANDLE, ">$opt{'o'}")) {
+		die "Sorry, cannot open $opt{'o'} $!\n";
+	}
+	select OUTPUT_HANDLE;
+}
+#
+# collect all the symbols and their attributes from the
+# Module.symvers file
+#
+while ( <MODULE_SYMVERS> ) {
+	chomp;
+	my (undef, $symbol, $module, $gpl) = split;
+	$SYMBOL { $symbol } =  [ $module , "0" , $symbol, $gpl];
+}
+close(MODULE_SYMVERS);
+
+#
+# collect the usage count of each symbol.
+#
+foreach my $thismod (@allcfiles) {
+	unless (open(MODULE_MODULE, $thismod)) {
+		print "Sorry, cannot open $thismod: $!\n";
+		next;
+	}
+	while ( <MODULE_MODULE> ) {
+		chomp;
+		if ( $_ !~ /0x[0-9a-f]{7,8},/ ) {
+			next;
+		}
+		my $sym = (split /([,"])/,)[4];
+		my ($module, $value, $symbol, $gpl) = @{$SYMBOL{$sym}};
+		$SYMBOL{ $sym } =  [ $module, $value+1, $symbol, $gpl];
+		push(@{$MODULE{$thismod}} , $sym);
+	}
+	close(MODULE_MODULE);
+}
+
+print "\tTHIS FILE REPORTS THE USAGE PATTERNS OF EXPORTED SYMBOLS BY IN_TREE\n";
+print "\t\t\t\tMODULES\n";
+printf("%s\n\n\n","x"x80);
+printf("\t\t\t\tINDEX\n\n\n");
+printf("SECTION 1: USAGE COUNTS OF ALL EXPORTED SYMBOLS\n");
+printf("SECTION 2: LIST OF MODULES AND THE EXPORTED SYMBOLS THEY USE\n");
+printf("%s\n\n\n","x"x80);
+printf("SECTION 1:\tTHE EXPORTED SYMBOLS AND THEIR USAGE COUNT\n\n");
+printf("%-25s\t%-25s\t%-5s\t%-25s\n", "SYMBOL", "MODULE", "USAGE COUNT",
+	"EXPORT TYPE");
+
+#
+# print the list of unused exported symbols
+#
+foreach my $list (sort alphabetically values(%SYMBOL)) {
+	my ($module, $value, $symbol, $gpl) = @{$list};
+	printf("%-25s\t%-25s\t%-10s\t", $symbol, $module, $value);
+	if (defined $gpl) {
+		printf("%-25s\n",$gpl);
+	} else {
+		printf("\n");
+	}
+}
+printf("%s\n\n\n","x"x80);
+
+printf("SECTION 2:\n\tThis section reports export-symbol-usage of in-kernel
+modules. Each module lists the modules, and the symbols from that module that
+it uses.  Each listed symbol reports the number of modules using it\n");
+
+print "~"x80 , "\n";
+while (my ($thismod, $list) = each %MODULE) {
+	my %depends;
+	$thismod =~ s/\.mod\.c/.ko/;
+	print "\t\t\t$thismod\n";
+	foreach my $symbol (@{$list}) {
+		my ($module, $value, undef, $gpl) = @{$SYMBOL{$symbol}};
+		push (@{$depends{"$module"}}, "$symbol $value");
+	}
+	print_depends_on(\%depends);
+}
Index: linux-2.6.17-rc3/Makefile
===================================================================
--- linux-2.6.17-rc3.orig/Makefile
+++ linux-2.6.17-rc3/Makefile
@@ -207,7 +207,7 @@ endif
 #	in addition to whatever we do anyway.
 #	Just "make" or "make all" shall build modules as well
 
-ifneq ($(filter all _all modules,$(MAKECMDGOALS)),)
+ifneq ($(filter all _all modules exportcheck,$(MAKECMDGOALS)),)
   KBUILD_MODULES := 1
 endif
 
@@ -1029,6 +1029,8 @@ help:
 	@echo  '  cscope	  - Generate cscope index'
 	@echo  '  kernelrelease	  - Output the release version string'
 	@echo  '  kernelversion	  - Output the version stored in Makefile'
+	@echo  '  exportcheck [EXPORTFILE=file]  - Export symbol usage analysis '
+	@echo  '				on compiled kernel'
 	@echo  ''
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
@@ -1258,6 +1260,18 @@ versioncheck:
 namespacecheck:
 	$(PERL) $(srctree)/scripts/namespace.pl
 
+ifeq ($(MAKECMDGOALS), exportcheck)
+  	KBUILD_EXPORT_REPORT := 1
+	ifdef EXPORTFILE
+	  ifeq ("$(origin EXPORTFILE)", "command line")
+  		KBUILD_EXPORT_REPORT = $(EXPORTFILE)
+	  endif
+	endif
+	export KBUILD_EXPORT_REPORT
+endif
+PHONY += exportcheck
+exportcheck: vmlinux modules
+
 endif #ifeq ($(config-targets),1)
 endif #ifeq ($(mixed-targets),1)