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 2421CCA9ECF for ; Fri, 1 Nov 2019 22:12:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8CA221D71 for ; Fri, 1 Nov 2019 22:12:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TUOCiu9g" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727828AbfKAWMQ (ORCPT ); Fri, 1 Nov 2019 18:12:16 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:56501 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727797AbfKAWMO (ORCPT ); Fri, 1 Nov 2019 18:12:14 -0400 Received: by mail-pf1-f202.google.com with SMTP id v11so8416994pfm.23 for ; Fri, 01 Nov 2019 15:12:14 -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=bw/qAOzuJX7ixoBqz2PQ7jd7OYMX5ZXLMotdDh+Bihs=; b=TUOCiu9gLsLFy3Xp5OD9ee3T44RBZ9XBgIe7yt7CvNj98C6CBu9wAFiKO2vk8DcyhT Ji59uJo30gvV4E1Mc6+k9TAjV16C8IiKMXK7G0oVHeV/PAz2/fCEaRJcdINYSGhgESYR uoDTe09Jv1qncBGnVBU6OT6bb8ZxBNJKvMf1wcI0ooElnCm2FCe3Y7+zQ6a97/j39xPN Mu+yrOgb1hl2vY4VIkbI6qMmyB8qwY3HwJfeslpY+sqKd7Pkx4hNMy+qAjpsXmuINSXH Hbqb76hzhJWPhHLLM3oT+0GxKRDzWsCq1m6N3+XuHnyEuX9+4K1XJa7mKQznVdZHeHhv 741g== 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=bw/qAOzuJX7ixoBqz2PQ7jd7OYMX5ZXLMotdDh+Bihs=; b=Y+s75O2CLxVDmyzHfPYBIL5rKveL8bVVRFxCCQFGAsrWcv5kYe2D0V9efRHXv+6Bps 3SWeUZsRKPy1wN/WMqIyK8lOX9wZqi5gpYYTm+JVzz1pOwrPy8LKhCTRaXrzohdR/Jrt HBIlpBbcOHtNwQZYi6sPYtMwq3uDPnKbh5O5OFvKndOo/TdDMMKpyyLKLN+gj1jGV6vG PmqRu4xWxBna+U53N6sbYEntz7K+TfTRGz9Vlm2dI9CIdYhq65HdXf7KldW6G0Twlo3n A3uCbS/9QCk15OpFZBV4TqX5Vb5exvd7/malJyDkexYYWPwLCAY3pDeV+cQI0C7x5jx1 nP+g== X-Gm-Message-State: APjAAAVio0HG1ajhj0J/bVqWVBWzks/M9sZcptlmf6e9M+nGPErgy3l/ j9PHrZHpN4+ceDeQgvJbVH3+HxrZ0UfIVKj/ovg= X-Google-Smtp-Source: APXvYqx5AqsiV5gsrjTxTPakMbZqpZkpOWKFfa4kZ0m+C6pXJ6/DO3wHTK1s5AzNd4GAvsVbgqAkyBlJLNLHZ9Ye4kg= X-Received: by 2002:a63:5762:: with SMTP id h34mr16176849pgm.235.1572646333610; Fri, 01 Nov 2019 15:12:13 -0700 (PDT) Date: Fri, 1 Nov 2019 15:11:40 -0700 In-Reply-To: <20191101221150.116536-1-samitolvanen@google.com> Message-Id: <20191101221150.116536-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.rc1.363.gb1bccd3e3d-goog Subject: [PATCH v4 07/17] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , 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. When enabled, also prints out the highest shadow stack usage per process. 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 7780fc4e29ac..67c43af627d1 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -167,6 +167,44 @@ 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; @@ -181,6 +219,7 @@ void scs_release(struct task_struct *tsk) return; WARN_ON(scs_corrupted(tsk)); + scs_check_usage(tsk); scs_account(tsk, -1); task_set_scs(tsk, NULL); -- 2.24.0.rc1.363.gb1bccd3e3d-goog