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 X-Spam-Level: X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 845ABC433C1 for ; Tue, 23 Mar 2021 14:31:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 418E9619B1 for ; Tue, 23 Mar 2021 14:31:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232296AbhCWObZ (ORCPT ); Tue, 23 Mar 2021 10:31:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:33876 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232186AbhCWObM (ORCPT ); Tue, 23 Mar 2021 10:31:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D98026191F; Tue, 23 Mar 2021 14:31:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616509871; bh=D6pTLSJCRpfh2oXokGcyBU20V0xCNExvFA1A+tFPPuE=; h=From:To:Cc:Subject:Date:From; b=eIO7RJw8c8tfFbHT9KHjShbcnOxPcjAURhHBpr9GhD/BN6Jdyg+4HY7krtO/GxRxD CiVDQIoc7GESO2nU9tBEvgz6c6feSYlgv6wBl+qDWHL5upVUDCHvSzLmDBGYzG/3wK ke1xOyaCDFRIMXTIsJLd/JNQnKS8xiQqnRxgewYjrKV85+19J0JEPvuLnt2m2DmCts lOjmNvlVB9Gq4f7vZqoywVkHVoKf7mTfxngsXu0+OSrsc2JvEk1xZnMf8ILXrZWixK OVH7DTpcJuGYfpMZXBx98+89DKjTGuRmav23JfkgQnQ978DVatxbG2U45kWQ11XhD6 8RVqrBkCMSqWA== From: Jessica Yu To: Peter Zijlstra Cc: x86@kernel.org, rostedt@goodmis.org, jpoimboe@redhat.com, jbaron@akamai.com, ardb@kernel.org, sumit.garg@linaro.org, oliver.sang@intel.com, jarkko@kernel.org, linux-kernel@vger.kernel.org, Jessica Yu Subject: [PATCH] module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD Date: Tue, 23 Mar 2021 15:27:56 +0100 Message-Id: <20210323142756.11443-1-jeyu@kernel.org> X-Mailer: git-send-email 2.30.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dynamic code patching (alternatives, jump_label and static_call) can have sites in __exit code, even if __exit is never executed. Therefore __exit must be present at runtime, at least for as long as __init code is. Additionally, for jump_label and static_call, the __exit sites must also identify as within_module_init(), such that the infrastructure is aware to never touch them after module init -- alternatives are only ran once at init and hence don't have this particular constraint. By making __exit identify as __init for !MODULE_UNLOAD, the above is satisfied. So the section ordering should look like the following when !CONFIG_MODULE_UNLOAD, with the .exit sections moved to the init region of the module. Core section allocation order: .text .rodata __ksymtab_gpl __ksymtab_strings .note.* sections .bss .data .gnu.linkonce.this_module Init section allocation order: .init.text .exit.text .symtab .strtab [jeyu: thanks to Peter Zijlstra for most of the changelog] Link: https://lore.kernel.org/lkml/YFiuphGw0RKehWsQ@gunter/ Signed-off-by: Jessica Yu --- Do you want to take this patch with the other static_call patches? Or should I take this through modules-next? kernel/module.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 30479355ab85..173a09175511 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2802,7 +2802,11 @@ void * __weak module_alloc(unsigned long size) bool __weak module_init_section(const char *name) { +#ifndef CONFIG_MODULE_UNLOAD + return strstarts(name, ".init") || module_exit_section(name); +#else return strstarts(name, ".init"); +#endif } bool __weak module_exit_section(const char *name) @@ -3116,11 +3120,6 @@ static int rewrite_section_headers(struct load_info *info, int flags) */ shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset; -#ifndef CONFIG_MODULE_UNLOAD - /* Don't load .exit sections */ - if (module_exit_section(info->secstrings+shdr->sh_name)) - shdr->sh_flags &= ~(unsigned long)SHF_ALLOC; -#endif } /* Track but don't keep modinfo and version sections. */ -- 2.30.1