From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757288AbdELHUX (ORCPT ); Fri, 12 May 2017 03:20:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753841AbdELHUW (ORCPT ); Fri, 12 May 2017 03:20:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3B55D3D94E Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jeyu@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 3B55D3D94E Date: Fri, 12 May 2017 00:20:14 -0700 From: Jessica Yu To: Michael Ellerman Cc: linuxppc-dev@ozlabs.org, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/modules: If mprofile-kernel is enabled add it to vermagic Message-ID: <20170512072012.lbiuoqexbai75ypy@jeyu> References: <1494399469-17833-1-git-send-email-mpe@ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <1494399469-17833-1-git-send-email-mpe@ellerman.id.au> X-OS: Linux jeyu 4.11.0-rc2+ x86_64 User-Agent: NeoMutt/20161126 (1.7.1) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 12 May 2017 07:20:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +++ Michael Ellerman [10/05/17 16:57 +1000]: >On powerpc we can build the kernel with two different ABIs for mcount(), which >is used by ftrace. Kernels built with one ABI do not know how to load modules >built with the other ABI. The new style ABI is called "mprofile-kernel", for >want of a better name. > >Currently if we build a module using the old style ABI, and the kernel with >mprofile-kernel, when we load the module we'll oops something like: > > # insmod autofs4-no-mprofile-kernel.ko > ftrace-powerpc: Unexpected instruction f8810028 around bl _mcount > ------------[ cut here ]------------ > WARNING: CPU: 6 PID: 3759 at ../kernel/trace/ftrace.c:2024 ftrace_bug+0x2b8/0x3c0 > CPU: 6 PID: 3759 Comm: insmod Not tainted 4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269 #11 > ... > NIP [c0000000001eaa48] ftrace_bug+0x2b8/0x3c0 > LR [c0000000001eaff8] ftrace_process_locs+0x4a8/0x590 > Call Trace: > alloc_pages_current+0xc4/0x1d0 (unreliable) > ftrace_process_locs+0x4a8/0x590 > load_module+0x1c8c/0x28f0 > SyS_finit_module+0x110/0x140 > system_call+0x38/0xfc > ... > ftrace failed to modify > [] 0xd000000002a31024 > actual: 35:65:00:48 > >We can avoid this by including in the vermagic whether the kernel/module was >built with mprofile-kernel. Which results in: > > # insmod autofs4-pg.ko > autofs4: version magic > '4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269 SMP mod_unload modversions ' > should be > '4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269-dirty SMP mod_unload modversions mprofile-kernel' > insmod: ERROR: could not insert module autofs4-pg.ko: Invalid module format > >Signed-off-by: Michael Ellerman Looks good to me: Acked-by: Jessica Yu >--- > arch/powerpc/include/asm/module.h | 4 ++++ > 1 file changed, 4 insertions(+) > >diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h >index 53885512b8d3..6c0132c7212f 100644 >--- a/arch/powerpc/include/asm/module.h >+++ b/arch/powerpc/include/asm/module.h >@@ -14,6 +14,10 @@ > #include > > >+#ifdef CC_USING_MPROFILE_KERNEL >+#define MODULE_ARCH_VERMAGIC "mprofile-kernel" >+#endif >+ > #ifndef __powerpc64__ > /* > * Thanks to Paul M for explaining this. >-- >2.7.4 >