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,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 174FAC2BB55 for ; Thu, 16 Apr 2020 16:14:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3F9E20771 for ; Thu, 16 Apr 2020 16:14:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oaXHw4Oo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2506870AbgDPQNJ (ORCPT ); Thu, 16 Apr 2020 12:13:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2506832AbgDPQM5 (ORCPT ); Thu, 16 Apr 2020 12:12:57 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A14CDC061A0C for ; Thu, 16 Apr 2020 09:12:57 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id nk12so3348986pjb.0 for ; Thu, 16 Apr 2020 09:12:57 -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=0zoCAxwf9k6lfoo3cxV3l2Ts8Ighj8ILmpKvjJbqwvo=; b=oaXHw4OoNjSODYtqP+D86dNRDfH9pFvBIgL5AAghUBFYKnrbVWQbiCIYvMoV5G/92q eAijVWC8ga1IgT8f2InqqkXDfvnJOHAfEoJR4Tv3ygcBIFNB+3MRslx3FassUAy0Uatd KTgMwbBl3RKE4Te0j7hl6uSM+q2hHmXvTAE68O2Qqmw80ejmwBmIa/uQIk0Ea6awb4D/ kiUfpIC642BpdAmbbEnAoxCTXQxQ62KaUPmVGWnjnutLyFbIJjdlfDx/bJhA/U7yXFFD en3fX1+ixzUBoNEWIbC1MibOBSiJdNjGY0/wQFmuEOqMPTQHYahJnCQZvu4lXlhPO+Ut 3Uiw== 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=0zoCAxwf9k6lfoo3cxV3l2Ts8Ighj8ILmpKvjJbqwvo=; b=hcm3/VdLGQDfO/oCJ+EZYXbL6LwEAG0PJRUslspWAU7KsEkIAss27cfggX5+EQW3Lk dK1lMj1HPVRs3GaqOs90oj7w7IVf0c5ukNpDE7YKC+6VkOvPUKyVGLR5ztjiPZHre2I/ cleUkc/AJG5HQ+yH31J6d0KktgNs21fB0utOT3gdLE6CuZGtF0fm48eNOCMjY2ANGqOL dtMQvA59i2fnnXocF4C5Qk62KKPS1oTK9qOV+5DkBd2f856A9JQcD7QkjWskhRz760Gm WkrF7KIRW3niWGktrHxClnRHb2Ecs71fngt6SO5zlbPOME8JJ9k1QIp3TME9bFzypSU3 483Q== X-Gm-Message-State: AGi0PuZeyAMPoDoUVz8jBjaay5nCQAZYwXS3MHFfndU3Az/bQBPqOZiK tMcQrlLK5Hui84orxrS/bngq8lCG8Z70hn0JT3o= X-Google-Smtp-Source: APiQypKIig2VehAviH0oXuxl4EJ3M3D8ILlWZ/6oWMjPFzuhTA+6Vu4jAmcNZSFI+UI1yW8xrivvKTZYZblKhvZz34o= X-Received: by 2002:a63:d049:: with SMTP id s9mr30834027pgi.384.1587053577150; Thu, 16 Apr 2020 09:12:57 -0700 (PDT) Date: Thu, 16 Apr 2020 09:12:36 -0700 In-Reply-To: <20200416161245.148813-1-samitolvanen@google.com> Message-Id: <20200416161245.148813-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200416161245.148813-1-samitolvanen@google.com> X-Mailer: git-send-email 2.26.1.301.g55bc3eb7cb9-goog Subject: [PATCH v11 03/12] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , James Morse , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Masahiro Yamada , Michal Marek , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Masami Hiramatsu , Nick Desaulniers , Jann Horn , Miguel Ojeda , 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 Reviewed-by: Kees Cook --- kernel/scs.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/kernel/scs.c b/kernel/scs.c index 5245e992c692..ad74d13f2c0f 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -184,6 +184,44 @@ 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(p); + unsigned long s = (unsigned long)p; + + while (p < end && READ_ONCE_NOCHECK(*p)) + p++; + + return (unsigned long)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 (%d): highest shadow stack usage: %lu bytes\n", + tsk->comm, task_pid_nr(tsk), 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) { unsigned long *magic = scs_magic(__scs_base(tsk)); @@ -200,6 +238,7 @@ 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); -- 2.26.1.301.g55bc3eb7cb9-goog