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 C748CCA9EAF for ; Thu, 24 Oct 2019 22:52:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96A042084C for ; Thu, 24 Oct 2019 22:52:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Ghul3xFE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732413AbfJXWwJ (ORCPT ); Thu, 24 Oct 2019 18:52:09 -0400 Received: from mail-qk1-f202.google.com ([209.85.222.202]:56025 "EHLO mail-qk1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732326AbfJXWwD (ORCPT ); Thu, 24 Oct 2019 18:52:03 -0400 Received: by mail-qk1-f202.google.com with SMTP id h18so336631qkj.22 for ; Thu, 24 Oct 2019 15:52:03 -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=+pC1wUGnAfIzdtPt9JYqx48tH0ZogjxIc75X2woCblw=; b=Ghul3xFEQaQM5xzVBFQoG8U8HNwG42e7GeQtV27MTWSZRuGptIXTiXUGIjDHp/YIpT hClIyJ8yLd1+EE9qsR9Oss13EFC0aEBed0i7vXbPLw7n7Cz1HrHzSiWsA4EcykXlitoW K5h6f2Q+00V9aJmmUnI7P9/MLwLZ35DTumdhIT4mQ4ce7/IwgipCUWdP7+q+I8zT5OhO a+NHytq0v/YolBdJAa7n+PY0/a9IGtPsdaAIdeA5LZmh6S0ZyAYyOYEOeyhxqrKOFMvM QncsL/qfcrw8l2wQdAQW3JMAY3o7KpY74274D2H4sRGOglWCZipnGdOSYkKm6qs+y5EC TkYQ== 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=+pC1wUGnAfIzdtPt9JYqx48tH0ZogjxIc75X2woCblw=; b=g9JQH6xyf8w722+dLo0FYFEJVV9yxv3CbCIhr0t/auoDZW3GgmfmVfWYOA90yg3I/N sqO1GxsGBqnbGYsAA5XBS/0D61TbuaMqLiD/ma6iNxKGfyBe6NTzQL23vVgcPA7ZHgsP y6Lcwiw/l0svaobH8VyiDg4NhxdjHC1wa78UsXmmN9HwvPahItW8z3ZUgEtV60Q2XKwX VONSb/dEqITxsYxQrLqsCLyh/c1AzJOKcYwi7/3/hoahuEXdClcQXF3R+Rg6/t7GYVhH uYbqd/hZpAMFHQsCMLRvPhT5+ni+RUCi8O395C56iZt90feMk5c6WUPo6IXxYqR8idoI o4HQ== X-Gm-Message-State: APjAAAVTE5CdfvR65X0AB6+SBvrC5V7AkVu6dnlb4Z+HvRIIXONJyhDE fQqio6HduqojgmU6RT1s1MIgg9so8s97b7Zl36s= X-Google-Smtp-Source: APXvYqzM3I26bKb3wrnFe0tgT6a7QNS7VGM2eEEUUuU2H4VKLgtcE0Bg1aj8IG0janwPGy/Kg+c3iOCkFYjR2Y2rhpw= X-Received: by 2002:a0c:e6e5:: with SMTP id m5mr375068qvn.170.1571957522490; Thu, 24 Oct 2019 15:52:02 -0700 (PDT) Date: Thu, 24 Oct 2019 15:51:22 -0700 In-Reply-To: <20191024225132.13410-1-samitolvanen@google.com> Message-Id: <20191024225132.13410-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191024225132.13410-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 07/17] scs: add support for stack usage debugging From: samitolvanen@google.com To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , 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. 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 b9e6e225254f..a5bf7d12dc13 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -154,6 +154,44 @@ 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; @@ -168,6 +206,7 @@ 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); -- 2.24.0.rc0.303.g954a862665-goog