name : generate_initcall_order.pl #!/usr/bin/env perl # SPDX-License-Identifier: GPL-2.0 # # Generates a linker script that specifies the correct initcall order. # # Copyright (C) 2019 Google LLC use strict; use warnings; use IO::Handle; use IO::Select; use POSIX ":sys_wait_h"; my $nm = $ENV{'NM'} || die "$0: ERROR: NM not set?"; my $objtree = $ENV{'objtree'} || '.'; ## currently active child processes my $jobs = {}; # child process pid -> file handle ## results from child processes my $results = {}; # object index -> [ { level, secname }, ... ] ## reads _NPROCESSORS_ONLN to determine the maximum number of processes to ## start sub get_online_processors { open(my $fh, "getconf _NPROCESSORS_ONLN 2>/dev/null |") or die "$0: ERROR: failed to execute getconf: $!"; my $procs = <$fh>; close($fh); if (!($procs =~ /^\d+$/)) { return 1; } return int($procs); } ## writes results to the parent process ## format: <file index> <initcall level> <base initcall section name> sub write_results { my ($index, $initcalls) = @_; # sort by the counter value to ensure the order of initcalls within # each object file is correct foreach my $counter (sort { $a <=> $b } keys(%{$initcalls})) { my $level = $initcalls->{$counter}->{'level'}; # section name for the initcall function my $secname = $initcalls->{$counter}->{'module'} . '__' . $counter . '_' . $initcalls->{$counter}->{'line'} . '_' . $initcalls->{$counter}->{'function'}; print "$index $level $secname\n"; } } ## reads a result line from a child process and adds it to the $results array sub read_results{ my ($fh) = @_; # each child prints out a full line w/ autoflush and exits after the # last line, so even if buffered I/O blocks here, it shouldn't block # very long my $data = <$fh>; if (!defined($data)) { return 0; } chomp($data); my ($index, $level, $secname) = $data =~ /^(\d+)\ ([^\ ]+)\ (.*)$/; if (!defined($index) || !defined($level) || !defined($secname)) { die "$0: ERROR: child process returned invalid data: $data\n"; } $index = int($index); if (!exists($results->{$index})) { $results->{$index} = []; } push (@{$results->{$index}}, { 'level' => $level, 'secname' => $secname }); return 1; } ## finds initcalls from an object file or all object files in an archive, and ## writes results back to the parent process sub find_initcalls { my ($index, $file) = @_; die "$0: ERROR: file $file doesn't exist?" if (! -f $file); open(my $fh, "\"$nm\" --defined-only \"$file\" 2>/dev/null |") or die "$0: ERROR: failed to execute \"$nm\": $!"; my $initcalls = {}; while (<$fh>) { chomp; # check for the start of a new object file (if processing an # archive) my ($path)= $_ =~ /^(.+)\:$/; if (defined($path)) { write_results($index, $initcalls); $initcalls = {}; next; } # look for an initcall my ($module, $counter, $line, $symbol) = $_ =~ /[a-z]\s+__initcall__(\S*)__(\d+)_(\d+)_(.*)$/; if (!defined($module)) { $module = '' } if (!defined($counter) || !defined($line) || !defined($symbol)) { next; } # parse initcall level my ($function, $level) = $symbol =~ /^(.*)((early|rootfs|con|[0-9])s?)$/; die "$0: ERROR: invalid initcall name $symbol in $file($path)" if (!defined($function) || !defined($level)); $initcalls->{$counter} = { 'module' => $module, 'line' => $line, 'function' => $function, 'level' => $level, }; } close($fh); write_results($index, $initcalls); } ## waits for any child process to complete, reads the results, and adds them to ## the $results array for later processing sub wait_for_results { my ($select) = @_; my $pid = 0; do { # unblock children that may have a full write buffer foreach my $fh ($select->can_read(0)) { read_results($fh); } # check for children that have exited, read the remaining data # from them, and clean up $pid = waitpid(-1, WNOHANG); if ($pid > 0) { if (!exists($jobs->{$pid})) { next; } my $fh = $jobs->{$pid}; $select->remove($fh); while (read_results($fh)) { # until eof } close($fh); delete($jobs->{$pid}); } } while ($pid > 0); } ## forks a child to process each file passed in the command line and collects ## the results sub process_files { my $index = 0; my $njobs = $ENV{'PARALLELISM'} || get_online_processors(); my $select = IO::Select->new(); while (my $file = shift(@ARGV)) { # fork a child process and read it's stdout my $pid = open(my $fh, '-|'); if (!defined($pid)) { die "$0: ERROR: failed to fork: $!"; } elsif ($pid) { # save the child process pid and the file handle $select->add($fh); $jobs->{$pid} = $fh; } else { # in the child process STDOUT->autoflush(1); find_initcalls($index, "$objtree/$file"); exit; } $index++; # limit the number of children to $njobs if (scalar(keys(%{$jobs})) >= $njobs) { wait_for_results($select); } } # wait for the remaining children to complete while (scalar(keys(%{$jobs})) > 0) { wait_for_results($select); } } sub generate_initcall_lds() { process_files(); my $sections = {}; # level -> [ secname, ...] # sort results to retain link order and split to sections per # initcall level foreach my $index (sort { $a <=> $b } keys(%{$results})) { foreach my $result (@{$results->{$index}}) { my $level = $result->{'level'}; if (!exists($sections->{$level})) { $sections->{$level} = []; } push(@{$sections->{$level}}, $result->{'secname'}); } } die "$0: ERROR: no initcalls?" if (!keys(%{$sections})); # print out a linker script that defines the order of initcalls for # each level print "SECTIONS {\n"; foreach my $level (sort(keys(%{$sections}))) { my $section; if ($level eq 'con') { $section = '.con_initcall.init'; } else { $section = ".initcall${level}.init"; } print "\t${section} : {\n"; foreach my $secname (@{$sections->{$level}}) { print "\t\t*(${section}..${secname}) ;\n"; } print "\t}\n"; } print "}\n"; } generate_initcall_lds();