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144ef909c0
When using CONFIG_RELOCATABLE, we build the kernel as a position independent executable. The kernel then uses a little bit of relocation code to relocate itself. That code only deals with R_PPC64_RELATIVE relocations though. If for some reason you use assembly constructs such as LOAD_REG_IMMEDIATE() to load the address of a symbol, you'll generate different kinds of relocations that won't be processed properly and bad things will happen. (We have 2 such bugs today). The perl script tries to filter out "known" bad ones. It's possible that we are missing some in the case of a weak function that nobody implements, we'll see if we get false positive and fix it. Signed-off-by: Tony Breeds <tony@bakeyournoodle.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
57 lines
1.3 KiB
Perl
Executable File
57 lines
1.3 KiB
Perl
Executable File
#!/usr/bin/perl
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# Copyright © 2009 IBM Corporation
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version
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# 2 of the License, or (at your option) any later version.
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# This script checks the relcoations of a vmlinux for "suspicious"
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# relocations.
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use strict;
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use warnings;
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if ($#ARGV != 1) {
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die "$0 [path to objdump] [path to vmlinux]\n";
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}
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# Have Kbuild supply the path to objdump so we handle cross compilation.
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my $objdump = shift;
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my $vmlinux = shift;
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my $bad_relocs_count = 0;
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my $bad_relocs = "";
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my $old_binutils = 0;
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open(FD, "$objdump -R $vmlinux|") or die;
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while (<FD>) {
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study $_;
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# Only look at relcoation lines.
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next if (!/\s+R_/);
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# These relocations are okay
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next if (/R_PPC64_RELATIVE/ or /R_PPC64_NONE/ or
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/R_PPC64_ADDR64\s+mach_/);
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# If we see this type of relcoation it's an idication that
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# we /may/ be using an old version of binutils.
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if (/R_PPC64_UADDR64/) {
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$old_binutils++;
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}
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$bad_relocs_count++;
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$bad_relocs .= $_;
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}
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if ($bad_relocs_count) {
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print "WARNING: $bad_relocs_count bad relocations\n";
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print $bad_relocs;
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}
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if ($old_binutils) {
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print "WARNING: You need at binutils >= 2.19 to build a ".
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"CONFIG_RELCOATABLE kernel\n";
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}
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