From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29154C761AF for ; Thu, 30 Mar 2023 07:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229838AbjC3Htd (ORCPT ); Thu, 30 Mar 2023 03:49:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229750AbjC3Ht0 (ORCPT ); Thu, 30 Mar 2023 03:49:26 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A33BB6EAC; Thu, 30 Mar 2023 00:49:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id C7B66CE278E; Thu, 30 Mar 2023 07:49:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48BB2C4339E; Thu, 30 Mar 2023 07:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680162545; bh=euhxm4vC64BtVaPf8+4nBzNG5RrVIhtI/ZRKJNYJ4sg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C98FLKJvzntj7hCOAMFU+R4Ws2Cbw7uabZMxqiC0wdz2w1IHHq2XM5KMoXNVKmYPv PFaLDQCHLKa+8UAx3GZqxoe9eZJRy9Uku8aMFAmWIqaLogFSIZ7DV6LsVDSWN35/FN 2gevljv7PWHZsMiWFJbJ3D5dZTip61hCMQ5AJ5u9HtwySBMKK9Vgrd3qFCBojDY8Hb 0NAD1DiNzfME7co1LNBc+yoRlyXGeCdIaOPfMGDd1Cj/nhktZ5YokOKmSsmSbJeZI4 OllKSBfeUUcqQh8pOQBROp4Y6+Tzk+FlwdAiejZ+82VKOIjEpUxHNoqdDRFXm1xQrE FJGJgOsHM/wIQ== Date: Thu, 30 Mar 2023 09:48:59 +0200 From: Simon Horman To: Ricardo Ribalda Cc: Eric Biederman , linux-kernel@vger.kernel.org, Baoquan He , stable@vger.kernel.org, Ross Zwisler , Philipp Rudo , Steven Rostedt , kexec@lists.infradead.org Subject: Re: [PATCH v4 1/2] kexec: Support purgatories with .text.hot sections Message-ID: References: <20230321-kexec_clang16-v4-0-1340518f98e9@chromium.org> <20230321-kexec_clang16-v4-1-1340518f98e9@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230321-kexec_clang16-v4-1-1340518f98e9@chromium.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Mar 27, 2023 at 05:06:53PM +0200, Ricardo Ribalda wrote: > Clang16 links the purgatory text in two sections: > > [ 1] .text PROGBITS 0000000000000000 00000040 > 00000000000011a1 0000000000000000 AX 0 0 16 > [ 2] .rela.text RELA 0000000000000000 00003498 > 0000000000000648 0000000000000018 I 24 1 8 > ... > [17] .text.hot. PROGBITS 0000000000000000 00003220 > 000000000000020b 0000000000000000 AX 0 0 1 > [18] .rela.text.hot. RELA 0000000000000000 00004428 > 0000000000000078 0000000000000018 I 24 17 8 > > And both of them have their range [sh_addr ... sh_addr+sh_size] on the > area pointed by `e_entry`. > > This causes that image->start is calculated twice, once for .text and > another time for .text.hot. The second calculation leaves image->start > in a random location. > > Because of this, the system crashes inmediatly after: s/inmediatly/immediately/ > > kexec_core: Starting new kernel > > Cc: stable@vger.kernel.org Maybe a fixes tag is warranted here. > Reviewed-by: Ross Zwisler > Signed-off-by: Ricardo Ribalda > --- > kernel/kexec_file.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index f1a0e4e3fb5c..25a37d8f113a 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -901,10 +901,21 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, > } > > offset = ALIGN(offset, align); > + > + /* > + * Check if the segment contains the entry point, if so, > + * calculate the value of image->start based on it. > + * If the compiler has produced more than one .text sections nit: s/sections/section/ > + * (Eg: .text.hot), they are generally after the main .text If this is the general case, then are there cases where this doesn't hold? > + * section, and they shall not be used to calculate > + * image->start. So do not re-calculate image->start if it > + * is not set to the initial value. > + */ > if (sechdrs[i].sh_flags & SHF_EXECINSTR && > pi->ehdr->e_entry >= sechdrs[i].sh_addr && > pi->ehdr->e_entry < (sechdrs[i].sh_addr > - + sechdrs[i].sh_size)) { > + + sechdrs[i].sh_size) && > + kbuf->image->start == pi->ehdr->e_entry) { > kbuf->image->start -= sechdrs[i].sh_addr; > kbuf->image->start += kbuf->mem + offset; > } > > -- > 2.40.0.348.gf938b09366-goog-b4-0.11.0-dev-696ae > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec >