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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 784F5CA9EA9 for ; Fri, 18 Oct 2019 16:11:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50359222C6 for ; Fri, 18 Oct 2019 16:11:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uErhWC3l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502540AbfJRQLQ (ORCPT ); Fri, 18 Oct 2019 12:11:16 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:51607 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732328AbfJRQLN (ORCPT ); Fri, 18 Oct 2019 12:11:13 -0400 Received: by mail-pf1-f202.google.com with SMTP id s137so4952508pfs.18 for ; Fri, 18 Oct 2019 09:11:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=+oBtFp6IQZ5946CFExp5BXllfwypP5AUtOYhvu+6eDg=; b=uErhWC3lFP8THQ9YjycpXkAl85COCd6lh+RqxQAfdCNUSVTiEfspc2alvbCgArV2fu ls4p2vGwJ3M8+8dC+pxUbBcocxnmbIOx1oZI7haycpR/idqzr0yRfNB9QU0r3L0Ad+LB AODIdu+bBRBco2jvuX999sV5JPTfKSeK6DQgqagm1V48qwgIQ9QQo3kPVBNgSxrwUzDc J7z1g1ZIddJjuwZ9NXT+KTuZuEnEru2YIfSdVRPO6N1MNFiWgJDAJs9A6AicwQY5z5mf Ozj1xQ9RCTG/l6zakh/4DEHsBfg5zP3zC8lFWduaZXJzlKOfJV8siLAxWkKPzGoNNYpY BIXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=+oBtFp6IQZ5946CFExp5BXllfwypP5AUtOYhvu+6eDg=; b=as3hmCfz7S7byGXcozV+VI4gbB53mhJGEX9v4Dg2vuIpZmfRTSu32ELcmx3b80cbVm SqjE6NfyuVFXV0nnBWVpAv4ynMLJaShPug7ZVrC83BiNekvAMBgbTplARoXEWwQpgj5R 7oZRyBLM4NKO221y6Dj4ZC3ZTcalpfGF9/0lEso+rmDNqz4VCUpYtFSn+HyosxOOoXcT iSXmZrdSip57fuxnAp8oYT+Mm4edGYxFjMMvc8PeSOWANW2XW9BKX4j5iQTTW7jlhNMf ckejVkCDgTgbtFoB4e+0u/QaeyhzJCv3FS4AYQv7WIaCZvlcV/vSxHtSs6IFHUpvluFJ 2pRg== X-Gm-Message-State: APjAAAVlNyaV/aBrqRuKmJz1ASUcZDRT2CxifykRLURqjVgGsGBmdzTu ryDaajylh8UhfkjjU2lwl/1jy0JlNFKxL3N13Q0= X-Google-Smtp-Source: APXvYqxHqmmpD11MJRO6yuoyBvltYKFWJkQq7UxJVT4qvc6swUR9mDIPTvziXaDvcDGhe+mECq8Qr7PX0sGP/3daZE0= X-Received: by 2002:a63:7845:: with SMTP id t66mr10836733pgc.31.1571415070584; Fri, 18 Oct 2019 09:11:10 -0700 (PDT) Date: Fri, 18 Oct 2019 09:10:23 -0700 In-Reply-To: <20191018161033.261971-1-samitolvanen@google.com> Message-Id: <20191018161033.261971-9-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> X-Mailer: git-send-email 2.23.0.866.gb869b98d4c-goog Subject: [PATCH 08/18] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Implements CONFIG_DEBUG_STACK_USAGE for shadow stacks. Signed-off-by: Sami Tolvanen --- kernel/scs.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/kernel/scs.c b/kernel/scs.c index 0e3cba49ea1a..1ec5c5a8dfae 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -161,6 +161,44 @@ int scs_prepare(struct task_struct *tsk, int node) return 0; } +#ifdef CONFIG_DEBUG_STACK_USAGE +static inline unsigned long scs_used(struct task_struct *tsk) +{ + unsigned long *p = __scs_base(tsk); + unsigned long *end = scs_magic(tsk); + uintptr_t s = (uintptr_t)p; + + while (p < end && *p) + p++; + + return (uintptr_t)p - s; +} + +static void scs_check_usage(struct task_struct *tsk) +{ + static DEFINE_SPINLOCK(lock); + static unsigned long highest; + unsigned long used = scs_used(tsk); + + if (used <= highest) + return; + + spin_lock(&lock); + + if (used > highest) { + pr_info("%s: highest shadow stack usage %lu bytes\n", + __func__, used); + highest = used; + } + + spin_unlock(&lock); +} +#else +static inline void scs_check_usage(struct task_struct *tsk) +{ +} +#endif + bool scs_corrupted(struct task_struct *tsk) { return *scs_magic(tsk) != SCS_END_MAGIC; @@ -175,6 +213,7 @@ void scs_release(struct task_struct *tsk) return; WARN_ON(scs_corrupted(tsk)); + scs_check_usage(tsk); scs_account(tsk, -1); scs_task_init(tsk); -- 2.23.0.866.gb869b98d4c-goog