From 144ef909c09b60c97b3c20b69ea30abd1e60e54d Mon Sep 17 00:00:00 2001 From: Tony Breeds Date: Mon, 14 Sep 2009 19:57:02 +0000 Subject: powerpc: Check for unsupported relocs when using CONFIG_RELOCATABLE 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 Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/relocs_check.pl | 56 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100755 arch/powerpc/relocs_check.pl (limited to 'arch/powerpc/relocs_check.pl') diff --git a/arch/powerpc/relocs_check.pl b/arch/powerpc/relocs_check.pl new file mode 100755 index 000000000000..d2571096c3e9 --- /dev/null +++ b/arch/powerpc/relocs_check.pl @@ -0,0 +1,56 @@ +#!/usr/bin/perl + +# Copyright © 2009 IBM Corporation + +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License +# as published by the Free Software Foundation; either version +# 2 of the License, or (at your option) any later version. + +# This script checks the relcoations of a vmlinux for "suspicious" +# relocations. + +use strict; +use warnings; + +if ($#ARGV != 1) { + die "$0 [path to objdump] [path to vmlinux]\n"; +} + +# Have Kbuild supply the path to objdump so we handle cross compilation. +my $objdump = shift; +my $vmlinux = shift; +my $bad_relocs_count = 0; +my $bad_relocs = ""; +my $old_binutils = 0; + +open(FD, "$objdump -R $vmlinux|") or die; +while () { + study $_; + + # Only look at relcoation lines. + next if (!/\s+R_/); + + # These relocations are okay + next if (/R_PPC64_RELATIVE/ or /R_PPC64_NONE/ or + /R_PPC64_ADDR64\s+mach_/); + + # If we see this type of relcoation it's an idication that + # we /may/ be using an old version of binutils. + if (/R_PPC64_UADDR64/) { + $old_binutils++; + } + + $bad_relocs_count++; + $bad_relocs .= $_; +} + +if ($bad_relocs_count) { + print "WARNING: $bad_relocs_count bad relocations\n"; + print $bad_relocs; +} + +if ($old_binutils) { + print "WARNING: You need at binutils >= 2.19 to build a ". + "CONFIG_RELCOATABLE kernel\n"; +} -- cgit v1.2.2