Files
Gary Guo 0a4e704ad1 UBUNTU: SAUCE: modpost: support arbitrary symbol length in modversion
BugLink: https://bugs.launchpad.net/bugs/2007654

Currently modversion uses a fixed size array of size (64 - sizeof(long))
to store symbol names, thus placing a hard limit on length of symbols.
Rust symbols (which encodes crate and module names) can be quite a bit
longer. The length limit in kallsyms is increased to 512 for this reason.

It's a waste of space to simply expand the fixed array size to 512 in
modversion info entries. I therefore make it variably sized, with offset
to the next entry indicated by the initial "next" field.

In addition to supporting longer-than-56/60 byte symbols, this patch also
reduce the size for short symbols by getting rid of excessive 0 paddings.
There are still some zero paddings to ensure "next" and "crc" fields are
properly aligned.

This patch does have a tiny drawback that it makes ".mod.c" files generated
a bit less easy to read, as code like

	"\x08\x00\x00\x00\x78\x56\x34\x12"
	"symbol\0\0"

is generated as opposed to

	{ 0x12345678, "symbol" },

because the structure is now variable-length. But hopefully nobody reads
the generated file :)

Link: b8a94bfb33 ("kallsyms: increase maximum kernel symbol length to 512")
Link: https://github.com/Rust-for-Linux/linux/pull/379

Signed-off-by: Gary Guo <gary@garyguo.net>
(backported from https://lore.kernel.org/lkml/20230111161155.1349375-1-gary@garyguo.net/)
[ fix build error on s390x: always use a variable with TO_NATIVE() ]
[ add dummy NULL entry at the end of the modversion array ]
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
2024-03-11 09:40:28 +01:00

188 lines
4.5 KiB
Perl
Executable File

#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0-only
#
# (C) Copyright IBM Corporation 2006.
# Author : Ram Pai (linuxram@us.ibm.com)
#
# Usage: export_report.pl -k Module.symvers [-o report_file ] -f *.mod.c
#
use warnings;
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";
for my $mod (sort keys %$href) {
my $list = $href->{$mod};
print "\t$mod:\n";
foreach my $sym (sort numerically @{$list}) {
my ($symbol, $no) = split /\s+/, $sym;
printf("\t\t%-25s\n", $symbol);
}
print "\n";
}
print "\n";
print "~"x80 , "\n";
}
sub usage {
print "Usage: @_ -h -k Module.symvers [ -o outputfile ] \n",
"\t-f: treat all the non-option argument as .mod.c files. ",
"Recommend using this as the last option\n",
"\t-h: print detailed help\n",
"\t-k: the path to Module.symvers file. By default uses ",
"the file from the current directory\n",
"\t-o outputfile: output the report to outputfile\n";
exit 0;
}
sub collectcfiles {
my @file;
open my $fh, '< modules.order' or die "cannot open modules.order: $!\n";
while (<$fh>) {
s/\.ko$/.mod.c/;
push (@file, $_)
}
close($fh);
chomp @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";
}
open (my $module_symvers, '<', $opt{'k'})
or die "Sorry, cannot open $opt{'k'}: $!\n";
if (defined $opt{'o'}) {
open (my $out, '>', $opt{'o'})
or die "Sorry, cannot open $opt{'o'} $!\n";
select $out;
}
#
# collect all the symbols and their attributes from the
# Module.symvers file
#
while ( <$module_symvers> ) {
chomp;
my (undef, $symbol, $module, $gpl, $namespace) = split('\t');
$SYMBOL { $symbol } = [ $module , "0" , $symbol, $gpl];
}
close($module_symvers);
#
# collect the usage count of each symbol.
#
my $modversion_warnings = 0;
foreach my $thismod (@allcfiles) {
my $module;
unless (open ($module, '<', $thismod)) {
warn "Sorry, cannot open $thismod: $!\n";
next;
}
my $state=0;
while ( <$module> ) {
chomp;
if ($state == 0) {
$state = 1 if ($_ =~ /static const char ____versions/);
next;
}
if ($state == 1) {
$state = 2 if ($_ =~ /__used __section\("__versions"\)/);
next;
}
if ($state == 2) {
if ( $_ !~ /\\0"/ ) {
last if ($_ =~ /;/);
next;
}
my $sym = (split /(["\\])/,)[2];
my ($module, $value, $symbol, $gpl) = @{$SYMBOL{$sym}};
$SYMBOL{ $sym } = [ $module, $value+1, $symbol, $gpl];
push(@{$MODULE{$thismod}} , $sym);
}
}
if ($state != 2) {
warn "WARNING:$thismod is not built with CONFIG_MODVERSIONS enabled\n";
$modversion_warnings++;
}
close($module);
}
print "\tThis file reports the exported symbols usage patterns by in-tree\n",
"\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 "\nNOTE: Got $modversion_warnings CONFIG_MODVERSIONS warnings\n\n"
if $modversion_warnings;
print "~"x80 , "\n";
for my $thismod (sort keys %MODULE) {
my $list = $MODULE{$thismod};
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);
}