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 100A9C6FD1F for ; Wed, 22 Mar 2023 20:46:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230303AbjCVUqb (ORCPT ); Wed, 22 Mar 2023 16:46:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231582AbjCVUqP (ORCPT ); Wed, 22 Mar 2023 16:46:15 -0400 Received: from mail-il1-x130.google.com (mail-il1-x130.google.com [IPv6:2607:f8b0:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63F765C9D5 for ; Wed, 22 Mar 2023 13:42:22 -0700 (PDT) Received: by mail-il1-x130.google.com with SMTP id i19so10544899ila.10 for ; Wed, 22 Mar 2023 13:42:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679517742; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=PeLzAkC8ofe4r03oiTnUMuqRyEUnaMbKdmxdI/cMXiM=; b=kqhsjOaIgYeqkmaxknXrou/E9CAWLLXCWtke8nsMd+V+dAl8Ga7iynfXqBHTcRVMLF zLiOHRlLUHVULCL+pKdRDQ2qoJnga+m+BrogLYKkZ7JpHIg4qOwtY8UQR4Fkg1i/Ct4O UlKS3TeJhDOTfy9v1vVyHjn05NVO6hmcPAj/WLe08+vavEqYhAdZ3frgHvAwvHzMa5C7 ch1CE72tMkDsQOScDRmZyqj1JaTc1fjB1GyGwOE9Y3QRU0F8SCxgycpIiAgaQAKxPPug xjeGyOIuX8JcCMJ9dpeBdsU5+obmhYIz4If+Vdv4GY5+HmVG+hA3aUq3d03iul6mCcJU PjWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679517742; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=PeLzAkC8ofe4r03oiTnUMuqRyEUnaMbKdmxdI/cMXiM=; b=JHp0ohnH9BfcPqEdZTkalRfGMumvZJckxRSGQswuyyxDWC4EpeZcDfmdCE2mwfNd+m 98BJ+4DlH0yHISeVxzHSKZ2oCFKVW1bN9Ea/IO2hX5PIWDQmtHxvLXQ/JBs0jkWH6FJY jaWIs7sl8+UzYsF1CtqZRcTOKEQXOUeNpZ3Iub9aJkcrPwsnUGRZAqJz1V4N0vgoMDrz IfS8Vwqp060Rm7OCBrgfMn7VQJik+h1/gyOBDz+5mhOa5ywUDncZ32FYH/PQtOXf4ZzT TpoelyHS/8twoQIhRB+4MJd+JFxly2pulTdEVyGyMXumD7JM3aUQX5FlcUDxd/Kd9aCs VZIg== X-Gm-Message-State: AO0yUKWnWpMvKLoLIUdGM+iHOulvx55mdNAmHOqQKEMEhUXoRD27WYzY 7ljOH+kpE74AuIujIkt54saW1F3g4EONU2KaO9+d0w== X-Google-Smtp-Source: AK7set/06aJHdEyDBbceHYokSH5vndvb5S1yTg7EcEj+8vu430ajLvdUnVHF0SntvV7+l8P8X7HezQ== X-Received: by 2002:a92:d102:0:b0:325:bc3f:f760 with SMTP id a2-20020a92d102000000b00325bc3ff760mr2290215ilb.0.1679517741531; Wed, 22 Mar 2023 13:42:21 -0700 (PDT) Received: from google.com ([2620:15c:183:200:7419:4945:3325:dd1e]) by smtp.gmail.com with ESMTPSA id y16-20020a027310000000b004061d6abcd1sm5274857jab.162.2023.03.22.13.42.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Mar 2023 13:42:21 -0700 (PDT) Date: Wed, 22 Mar 2023 14:42:17 -0600 From: Ross Zwisler To: Ricardo Ribalda Cc: Eric Biederman , linux-kernel@vger.kernel.org, Philipp Rudo , kexec@lists.infradead.org, Baoquan He Subject: Re: [PATCH v3] kexec: Support purgatories with .text.hot sections Message-ID: <20230322204217.GA3076000@google.com> References: <20230321-kexec_clang16-v3-0-5f016c8d0e87@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230321-kexec_clang16-v3-0-5f016c8d0e87@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 22, 2023 at 08:09:21PM +0100, 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: > > kexec_core: Starting new kernel > > Signed-off-by: Ricardo Ribalda Reviewed-by: Ross Zwisler > --- > kexec: Fix kexec_file_load for llvm16 > > When upreving llvm I realised that kexec stopped working on my test > platform. This patch fixes it. > > To: Eric Biederman > Cc: Baoquan He > Cc: Philipp Rudo > Cc: kexec@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > --- > Changes in v3: > - Fix initial value. Thanks Ross! > - Link to v2: https://lore.kernel.org/r/20230321-kexec_clang16-v2-0-d10e5d517869@chromium.org > > Changes in v2: > - Fix if condition. Thanks Steven!. > - Update Philipp email. Thanks Baoquan. > - Link to v1: https://lore.kernel.org/r/20230321-kexec_clang16-v1-0-a768fc2c7c4d@chromium.org > --- > 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 > + * (Eg: .text.hot), they are generally after the main .text > + * 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; > } > > --- > base-commit: 17214b70a159c6547df9ae204a6275d983146f6b > change-id: 20230321-kexec_clang16-4510c23d129c > > Best regards, > -- > Ricardo Ribalda