Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758206Ab3DXKOE (ORCPT ); Wed, 24 Apr 2013 06:14:04 -0400 Received: from multi.imgtec.com ([194.200.65.239]:53282 "EHLO multi.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754751Ab3DXKOC (ORCPT ); Wed, 24 Apr 2013 06:14:02 -0400 Message-ID: <5177B061.50107@imgtec.com> Date: Wed, 24 Apr 2013 11:13:53 +0100 From: James Hogan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: "H. Peter Anvin" , CC: Tetsuo Handa , , , Subject: Re: [PATCH] x86_32: Fix module version table mismatch. References: <201304222326.IJB21395.FOtVJFHFQMOOSL@I-love.SAKURA.ne.jp> <201304232140.FGF73904.QJOFOVtHFFMSOL@I-love.SAKURA.ne.jp> <51772CD3.3040405@zytor.com> <51772EBC.1050600@zytor.com> In-Reply-To: <51772EBC.1050600@zytor.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.154.65] X-SEF-Processed: 7_3_0_01181__2013_04_24_11_13_55 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2774 Lines: 78 On 24/04/13 02:00, H. Peter Anvin wrote: > On 04/23/2013 05:52 PM, H. Peter Anvin wrote: >> On 04/23/2013 05:40 AM, Tetsuo Handa wrote: >>> Commit a4b6a77b "module: fix symbol versioning with symbol prefixes" broke >>> loading of net/ipv6/ipv6.ko built with CONFIG_MODVERSIONS=y for x86_32. >> >> This really does seem to be the offending commit, although I'm still >> confused how the heck that is possible. >> > > OK, now I grok. > > The bug is the use of VMLINUX_SYMBOL_STR(%s) which expands at the time > the output of modpost is compiled. However, VMLINUX_SYMBOL_STR() unlike > __VMLINUX_SYMBOL_STR() does macro expansion on its argument, which is > actively wrong here. Yes, nasty bug there (sorry!) > I think the choice is either to change this to __VMLINUX_SYMBOL_STR() or > re-introduce CONFIG_SYMBOL_PREFIX (or its equivalent) so that modprobe > can emit it at compile time Using __VMLINUX_SYMBOL_STR looks like the correct solution to me. > (assuming there even should *be* a prefix on > the symbol here, i.e. that the compiler won't add it.) [__]VMLINUX_SYMBOL_STR expands to a string (e.g. "_" "memcmp" or just "memcmp") so the compiler won't touch it. > > Either way -- James, Rusty, this is in your court. How does the patch below look? I presume this is preferred over making VMLINUX_SYMBOL_STR non-argument-expanding? Thanks James Subject: [PATCH 1/1] modpost: fix unwanted VMLINUX_SYMBOL_STR expansion Commit a4b6a77b77ba4f526392612c2365797fab956014 ("module: fix symbol versioning with symbol prefixes") broke the MODVERSIONS loading of any module using memcmp (e.g. ipv6) on x86_32, as it's defined to __builtin_memcmp which is expanded by VMLINUX_SYMBOL_STR. Use __VMLINUX_SYMBOL_STR instead which doesn't expand the argument. Reported-by: Tetsuo Handa Signed-off-by: James Hogan Cc: Rusty Russell Cc: Andy Shevchenko Cc: H. Peter Anvin --- scripts/mod/modpost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 1f90961..a4be8e1 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1957,7 +1957,7 @@ static int add_versions(struct buffer *b, struct module *mod) s->name, mod->name); continue; } - buf_printf(b, "\t{ %#8x, VMLINUX_SYMBOL_STR(%s) },\n", + buf_printf(b, "\t{ %#8x, __VMLINUX_SYMBOL_STR(%s) },\n", s->crc, s->name); } -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/