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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,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 0E8F1C43381 for ; Mon, 25 Feb 2019 20:00:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C25632087C for ; Mon, 25 Feb 2019 20:00:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="fLqbVs3M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727084AbfBYUAI (ORCPT ); Mon, 25 Feb 2019 15:00:08 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:44906 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726692AbfBYUAH (ORCPT ); Mon, 25 Feb 2019 15:00:07 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1PJvN6I046999; Mon, 25 Feb 2019 20:00:05 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : subject : date : message-id; s=corp-2018-07-02; bh=SJjadGJSNzZF+UrL2IHlg0sQrJtHyFGp7uDt6saytdk=; b=fLqbVs3MhS1FIkDgr9oeUjQlsjLwq943+DbocLhQbpZ+V5Y3G24JT4PMj/1lAD2Ybb/G FijRkM6PBHbZuLMOJimEWoDkx9HQGVgNN4FPbmOpSMnr44r+xkLv5olEdBrHPogYtRx4 7j4hebUAcq2Qg0j2rSTEx1Qen7ImzT3Z4elKLezWLIpoz9L41VvWQ854LzEM9hEP6GsV pfyL7Y7WLNXbB/sezuXkdIbLbQNxmMkadIRhzcoCuLB4ilKvGkPgAa7rIe0E/k49n5jC rQpZqz/mTsAYlIC0tTVO5hoNtB95/+GRFRDDg960bEVpSL1/s93tls8w+Uta/v8wNgnW ZA== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2120.oracle.com with ESMTP id 2qtxtrg8hf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 25 Feb 2019 20:00:04 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x1PK03Cv024602 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 25 Feb 2019 20:00:03 GMT Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1PK02dU025139; Mon, 25 Feb 2019 20:00:03 GMT Received: from localhost.us.oracle.com (/10.211.15.82) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 25 Feb 2019 12:00:02 -0800 From: eugene.loh@oracle.com To: jeyu@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] kallsyms: store type information in its own array Date: Mon, 25 Feb 2019 11:59:58 -0800 Message-Id: <1551124798-12712-1-git-send-email-eugene.loh@oracle.com> X-Mailer: git-send-email 1.8.3.1 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9178 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902250144 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eugene Loh When a module is loaded, its symbols' Elf_Sym information is stored in a symtab. Further, type information is also captured. Since Elf_Sym has no type field, historically the st_info field has been hijacked for storing type: st_info was overwritten. commit 5439c985c5a83a8419f762115afdf560ab72a452 ("module: Overwrite st_size instead of st_info") changes that practice, as its one-liner indicates. Unfortunately, this change overwrites symbol size, information that a tool like DTrace expects to find. Allocate a typetab array to store type information so that no Elf_Sym field needs to be overwritten. Fixes: 5439c985c5a8 ("module: Overwrite st_size instead of st_info") Signed-off-by: Eugene Loh Reviewed-by: Nick Alcock --- include/linux/module.h | 1 + kernel/module-internal.h | 2 +- kernel/module.c | 21 ++++++++++++++------- 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index f5bc4c0..9c1bc21 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -315,6 +315,7 @@ struct mod_kallsyms { Elf_Sym *symtab; unsigned int num_symtab; char *strtab; + char *typetab; }; #ifdef CONFIG_LIVEPATCH diff --git a/kernel/module-internal.h b/kernel/module-internal.h index 79c9be2..67828af 100644 --- a/kernel/module-internal.h +++ b/kernel/module-internal.h @@ -20,7 +20,7 @@ struct load_info { unsigned long len; Elf_Shdr *sechdrs; char *secstrings, *strtab; - unsigned long symoffs, stroffs; + unsigned long symoffs, stroffs, init_typeoff, core_typeoff; struct _ddebug *debug; unsigned int num_debug; bool sig_ok; diff --git a/kernel/module.c b/kernel/module.c index 2ad1b52..c7c1bcd 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2647,6 +2647,8 @@ static void layout_symtab(struct module *mod, struct load_info *info) info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1); info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym); mod->core_layout.size += strtab_size; + info->core_typeoff = mod->core_layout.size; + mod->core_layout.size += ndst * sizeof(char); mod->core_layout.size = debug_align(mod->core_layout.size); /* Put string table section at end of init part of module. */ @@ -2660,6 +2662,8 @@ static void layout_symtab(struct module *mod, struct load_info *info) __alignof__(struct mod_kallsyms)); info->mod_kallsyms_init_off = mod->init_layout.size; mod->init_layout.size += sizeof(struct mod_kallsyms); + info->init_typeoff = mod->init_layout.size; + mod->init_layout.size += nsrc * sizeof(char); mod->init_layout.size = debug_align(mod->init_layout.size); } @@ -2683,20 +2687,23 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) mod->kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym); /* Make sure we get permanent strtab: don't use info->strtab. */ mod->kallsyms->strtab = (void *)info->sechdrs[info->index.str].sh_addr; + mod->kallsyms->typetab = mod->init_layout.base + info->init_typeoff; - /* Set types up while we still have access to sections. */ - for (i = 0; i < mod->kallsyms->num_symtab; i++) - mod->kallsyms->symtab[i].st_size - = elf_type(&mod->kallsyms->symtab[i], info); - - /* Now populate the cut down core kallsyms for after init. */ + /* + * Now populate the cut down core kallsyms for after init + * and set types up while we still have access to sections. + */ mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs; mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs; + mod->core_kallsyms.typetab = mod->core_layout.base + info->core_typeoff; src = mod->kallsyms->symtab; for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) { + mod->kallsyms->typetab[i] = elf_type(src + i, info); if (i == 0 || is_livepatch_module(mod) || is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum, info->index.pcpu)) { + mod->core_kallsyms.typetab[ndst] = + mod->kallsyms->typetab[i]; dst[ndst] = src[i]; dst[ndst++].st_name = s - mod->core_kallsyms.strtab; s += strlcpy(s, &mod->kallsyms->strtab[src[i].st_name], @@ -4084,7 +4091,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, const Elf_Sym *sym = &kallsyms->symtab[symnum]; *value = kallsyms_symbol_value(sym); - *type = sym->st_size; + *type = kallsyms->typetab[symnum]; strlcpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN); strlcpy(module_name, mod->name, MODULE_NAME_LEN); *exported = is_exported(name, *value, mod); -- 1.8.3.1