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260 lines
8.6 KiB
Perl
Executable File
260 lines
8.6 KiB
Perl
Executable File
#!/usr/bin/perl
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# vim:sw=4:ts=4:et:
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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# $Id: fix-linux-stack.pl,v 1.16 2008/05/05 21:51:11 dbaron%dbaron.org Exp $
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#
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# This script uses addr2line (part of binutils) to process the output of
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# nsTraceRefcnt's Linux stack walking code. This is useful for two
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# things:
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# (1) Getting line number information out of
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# |nsTraceRefcntImpl::WalkTheStack|'s output in debug builds.
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# (2) Getting function names out of |nsTraceRefcntImpl::WalkTheStack|'s
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# output on optimized builds (where it mostly prints UNKNOWN
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# because only a handful of symbols are exported from component
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# libraries).
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#
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# Use the script by piping output containing stacks (such as raw stacks
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# or make-tree.pl balance trees) through this script.
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use strict;
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use IPC::Open2;
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use File::Basename;
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# XXX Hard-coded to gdb defaults (works on Fedora).
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my $global_debug_dir = '/usr/lib/debug';
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# We record several things for each file encountered.
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#
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# - {pipe_read}, {pipe_write}: these constitute a bidirectional pipe to an
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# addr2line process that gives symbol information for a file.
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#
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# - {cache}: this table holds the results of lookups that we've done
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# previously for (pre-adjustment) addresses, which lets us avoid redundant
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# calls to addr2line.
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#
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# - {address_adjustment}: addr2line wants offsets relative to the base address
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# for shared libraries, but it wants addresses including the base address
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# offset for executables. This holds the appropriate address adjustment to
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# add to an offset within file. See bug 230336.
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#
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my %file_infos;
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sub set_address_adjustment($$) {
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my ($file, $file_info) = @_;
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# find out if it's an executable (as opposed to a shared library)
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my $elftype;
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open(ELFHDR, '-|', 'readelf', '-h', $file);
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while (<ELFHDR>) {
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if (/^\s*Type:\s+(\S+)/) {
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$elftype = $1;
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last;
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}
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}
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close(ELFHDR);
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# If it's an executable, make adjustment the base address.
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# Otherwise, leave it zero.
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my $adjustment = 0;
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if ($elftype eq 'EXEC') {
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open(ELFSECS, '-|', 'readelf', '-S', $file);
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while (<ELFSECS>) {
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if (/^\s*\[\s*\d+\]\s+\.text\s+\w+\s+(\w+)\s+(\w+)\s+/) {
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# Subtract the .text section's offset within the
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# file from its base address.
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$adjustment = hex($1) - hex($2);
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last;
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}
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}
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close(ELFSECS);
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}
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$file_info->{address_adjustment} = $adjustment;
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}
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# Files sometimes contain a link to a separate object file that contains
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# the debug sections of the binary, removed so that a smaller file can
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# be shipped, but kept separately so that it can be obtained by those
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# who want it.
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# See http://sources.redhat.com/gdb/current/onlinedocs/gdb_16.html#SEC154
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# for documentation of debugging information in separate files.
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# On Fedora distributions, these files can be obtained by installing
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# *-debuginfo RPM packages.
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sub separate_debug_file_for($) {
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my ($file) = @_;
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# We can read the .gnu_debuglink section using either of:
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# objdump -s --section=.gnu_debuglink $file
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# readelf -x .gnu_debuglink $file
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# Since readelf prints things backwards on little-endian platforms
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# for some versions only (backwards on Fedora Core 6, forwards on
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# Fedora 7), use objdump.
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# See if there's a .gnu_debuglink section
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my $have_debuglink = 0;
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open(ELFSECS, '-|', 'readelf', '-S', $file);
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while (<ELFSECS>) {
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if (/^\s*\[\s*\d+\]\s+\.gnu_debuglink\s+\w+\s+(\w+)\s+(\w+)\s+/) {
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$have_debuglink = 1;
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last;
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}
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}
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close(ELFSECS);
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return '' unless ($have_debuglink);
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# Determine the endianness of the shared library.
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my $endian = '';
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open(ELFHDR, '-|', 'readelf', '-h', $file);
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while (<ELFHDR>) {
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if (/^\s*Data:\s+.*(little|big) endian.*$/) {
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$endian = $1;
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last;
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}
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}
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close(ELFHDR);
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if ($endian ne 'little' && $endian ne 'big') {
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print STDERR "Warning: could not determine endianness of $file.\n";
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return '';
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}
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# Read the debuglink section as an array of words, in hexidecimal.
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open(DEBUGLINK, '-|', 'objdump', '-s', '--section=.gnu_debuglink', $file);
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my @words;
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while (<DEBUGLINK>) {
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if ($_ =~ /^ [0-9a-f]* ([0-9a-f ]{8}) ([0-9a-f ]{8}) ([0-9a-f ]{8}) ([0-9a-f ]{8}).*/) {
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push @words, $1, $2, $3, $4;
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}
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}
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close(DEBUGLINK);
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while (@words[$#words] eq ' ') {
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pop @words;
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}
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if ($#words < 1) {
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print STDERR "Warning: .gnu_debuglink section in $file too short.\n";
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return '';
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}
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my @chars;
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while ($#words >= 0) {
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my $w = shift @words;
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if ($w =~ /^([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})$/) {
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push @chars, $1, $2, $3, $4;
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} else {
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print STDERR "Warning: malformed objdump output for $file.\n";
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return '';
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}
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}
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my @hash_bytes = map(hex, @chars[$#chars - 3 .. $#chars]);
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$#chars -= 4;
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my $hash;
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if ($endian eq 'little') {
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$hash = ($hash_bytes[3] << 24) | ($hash_bytes[2] << 16) | ($hash_bytes[1] << 8) | $hash_bytes[0];
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} else {
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$hash = ($hash_bytes[0] << 24) | ($hash_bytes[1] << 16) | ($hash_bytes[2] << 8) | $hash_bytes[3];
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}
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# The string ends with a null-terminator and then 0 to three bytes
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# of padding to fill the current 32-bit unit. (This padding is
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# usually null bytes, but I've seen null-null-H, on Ubuntu x86_64.)
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my $terminator = 1;
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while ($chars[$terminator] ne '00') {
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if ($terminator == $#chars) {
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print STDERR "Warning: missing null terminator in " .
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".gnu_debuglink section of $file.\n";
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return '';
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}
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++$terminator;
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}
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if ($#chars - $terminator > 3) {
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print STDERR "Warning: Excess padding in .gnu_debuglink section " .
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"of $file.\n";
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return '';
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}
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$#chars = $terminator - 1;
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my $basename = join('', map { chr(hex($_)) } @chars);
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# Now $basename and $hash represent the information in the
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# .gnu_debuglink section.
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#printf STDERR "%x: %s\n", $hash, $basename;
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my @possible_results = (
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dirname($file) . $basename,
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dirname($file) . '.debug/' . $basename,
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$global_debug_dir . dirname($file) . '/' . $basename
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);
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foreach my $result (@possible_results) {
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if (-f $result) {
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# XXX We should check the hash.
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return $result;
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}
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}
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return '';
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}
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sub get_file_info($) {
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my ($file) = @_;
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my $file_info = $file_infos{$file};
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unless (defined $file_info) {
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my $debug_file = separate_debug_file_for($file);
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$debug_file = $file if ($debug_file eq '');
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my $pid = open2($file_info->{pipe_read}, $file_info->{pipe_write},
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'/usr/bin/addr2line', '-C', '-f', '-e', $debug_file);
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set_address_adjustment($file, $file_info);
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$file_infos{$file} = $file_info;
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}
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return $file_info;
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}
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# Ignore SIGPIPE as a workaround for addr2line crashes in some situations.
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$SIG{PIPE} = 'IGNORE';
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select STDOUT; $| = 1; # make STDOUT unbuffered
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while (<>) {
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my $line = $_;
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if ($line =~ /^([ \|0-9-]*)(.*) ?\[([^ ]*) \+(0x[0-9A-F]{1,8})\](.*)$/) {
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my $before = $1; # allow preservation of balance trees
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my $badsymbol = $2;
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my $file = $3;
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my $address = hex($4);
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my $after = $5; # allow preservation of counts
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if (-f $file) {
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my $file_info = get_file_info($file);
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my $result = $file_info->{cache}->{$address};
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if (not defined $result) {
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my $address2 = $address + $file_info->{address_adjustment};
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my $out = $file_info->{pipe_write};
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my $in = $file_info->{pipe_read};
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printf {$out} "0x%X\n", $address2;
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chomp(my $symbol = <$in>);
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chomp(my $fileandline = <$in>);
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if (!$symbol || $symbol eq '??') { $symbol = $badsymbol; }
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if (!$fileandline || $fileandline eq '??:0') {
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$fileandline = $file;
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}
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$result = "$symbol ($fileandline)";
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$file_info->{cache}->{$address} = $result;
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}
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print "$before$result$after\n";
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} else {
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print STDERR "Warning: File \"$file\" does not exist.\n";
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print $line;
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}
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} else {
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print $line;
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}
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}
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