Quelle generate_initcall_order.pl
Sprache: unbekannt
#!/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>;
## 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;
}
## 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} = [];
}
