From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757194AbXGAWNo (ORCPT ); Sun, 1 Jul 2007 18:13:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751820AbXGAWNh (ORCPT ); Sun, 1 Jul 2007 18:13:37 -0400 Received: from gw.goop.org ([64.81.55.164]:34410 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751789AbXGAWNg (ORCPT ); Sun, 1 Jul 2007 18:13:36 -0400 Message-ID: <4688270E.7020508@goop.org> Date: Sun, 01 Jul 2007 15:13:34 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.4 (X11/20070615) MIME-Version: 1.0 To: "Eric W. Biederman" CC: Adrian Bunk , Andrew Morton , Jeremy Fitzhardinge , Andi Kleen , chrisw@sous-sol.org, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org, Vivek Goyal Subject: Re: 2.6.22-rc6-mm1: Xen: WARNING: Absolute relocations present References: <20070628034321.38c9f12b.akpm@linux-foundation.org> <20070628204001.GA6087@stusta.de> <46841EC4.7080805@goop.org> <4687D744.6000103@goop.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric W. Biederman wrote: > Jeremy Fitzhardinge writes: > > > >>>> Adrian Bunk wrote: >>>> >>>> >>>>> <-- snip --> >>>>> >>>>> ... >>>>> RELOCS arch/i386/boot/compressed/vmlinux.relocs >>>>> WARNING: Absolute relocations present >>>>> Offset Info Type Sym.Value Sym.Name >>>>> c0101f80 020c6501 R_386_32 00000000 xen_irq_disable_direct_reloc >>>>> c0101f9a 0221ea01 R_386_32 00000000 xen_save_fl_direct_reloc >>>>> > Actually I have to ask. How in the world are these absolute symbols > ok from a relocation perspective. > > If the kernel is not running at 0xc0100000 the offset value looks like > it will be completely bogus. > Notice they're absolute 0. > Maybe those are ok, but if you could please explain why those are > false positives I would appreciate it. (Especially in your patch > description). > > If these are indeed false positives the patch looks ok. > Subject: xen: suppress abs symbol warnings for unused reloc pointers arch/i386/xen/xen-asm.S defines some small pieces of code which are used to implement a few paravirt_ops. They're designed so they can be used either in-place, or be inline patched into their callsites if there's enough space. Some of those operations need to make calls out (specifically, if you re-enable events [interrupts], and there's a pending event at that time). These calls need the call instruction to be relocated if the code is patched inline. In this case xen_foo_reloc is a section-relative symbol which points to xen_foo's required relocation. Other operations have no need of a relocation, and so their corresponding xen_bar_reloc is absolute 0. These are the cases which are triggering the warning. This patch adds those symbols to the list of safe abs symbols. Signed-off-by: Jeremy Fitzhardinge Cc: Adrian Bunk --- arch/i386/boot/compressed/relocs.c | 2 ++ 1 file changed, 2 insertions(+) =================================================================== --- a/arch/i386/boot/compressed/relocs.c +++ b/arch/i386/boot/compressed/relocs.c @@ -31,6 +31,8 @@ static const char* safe_abs_relocs[] = { "__kernel_rt_sigreturn", "__kernel_sigreturn", "SYSENTER_RETURN", + "xen_irq_disable_direct_reloc", + "xen_save_fl_direct_reloc", }; static int is_safe_abs_reloc(const char* sym_name)