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 918CAC2D0C1 for ; Fri, 6 Dec 2019 22:14:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64AE8206DB for ; Fri, 6 Dec 2019 22:14:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SXuPCZw5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726683AbfLFWOS (ORCPT ); Fri, 6 Dec 2019 17:14:18 -0500 Received: from mail-pg1-f201.google.com ([209.85.215.201]:39747 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726642AbfLFWOO (ORCPT ); Fri, 6 Dec 2019 17:14:14 -0500 Received: by mail-pg1-f201.google.com with SMTP id v2so1343676pgv.6 for ; Fri, 06 Dec 2019 14:14:14 -0800 (PST) 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=dSkqIg9MhTEqSRuUPD+wLwf3dmJwcSH5rhdG+lQGY0Y=; b=SXuPCZw5St6pvwTst8kmf5KElVFLKMFMp+CAkmkUaQLus5cyU/8kqr6V5JxAIwmDV8 RWdDAn+WZ18vV4T9eqQoonAjHW3Rzl/rq+nVdoOiKpP2KO897WS7qgb0uHjTrgJkEo1F 0w2fuPU7iE//Mhmc1AStldjXFL0gQujdjqFyhIQqo0PX3BYn+fe6w0aILNtXks9GiWbX y15Zqo4dF7akKdP8o3QHjsZgpRBi+Vh9QT2pwFLxPBRKjS+x9TmrUCopcszBpJQvv4wL EQLbAdHZz6TZ6uqyOto/Ft9UcaQoXc6w3u8Hni2mOOXu4O7zVJWi0IlEALO+ifSUBL0a F4QA== 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=dSkqIg9MhTEqSRuUPD+wLwf3dmJwcSH5rhdG+lQGY0Y=; b=ag/OkMXhRR4JLbQ9m1ef2TtPuwk0iupZTBo/Ta/7ICD55ui3E9A/3EJ1TFueObSNi+ 7nUrCNabp56wkO7alaZu8WUx7n72OPG+THhlxP+hW7e+q7+91OVplcwwZhTc5wi2d+EY dxN9R0cngWL97XmoQUXJgJJkn894KIGBsOoGBXbbY8i7GdskeVXNUvDdehZSlO3Wus+A ovkkRnEb/6UTTiH2yFLnqOl94V8zIfp/0TrCav7rLwjhBNDgigWhv7Hvjret51ZZFaVm moec5oABRpcvrpzGDDqWzSC5RzVJ0kiE7jtjqYxO8P8uy93TRZyzQykWxj7x0NxY92pB Y/DA== X-Gm-Message-State: APjAAAUzOHsxCb9V6kEOWakBMIaXrVt83e3hkdwTgDXPzQeDWU+UlKnd 2zqtrJ1GP9tqcJdJVCoNF64FYta0mICccNTbmwE= X-Google-Smtp-Source: APXvYqwr9gV3C2U9Vw8KNYzBqn9JcBiVcajDSJ2lm7uPyamXFOot36lh81Wh0+CfZKTc60xlWZW4gj6RW7XavjkgTmE= X-Received: by 2002:a63:4b52:: with SMTP id k18mr5960727pgl.371.1575670454000; Fri, 06 Dec 2019 14:14:14 -0800 (PST) Date: Fri, 6 Dec 2019 14:13:43 -0800 In-Reply-To: <20191206221351.38241-1-samitolvanen@google.com> Message-Id: <20191206221351.38241-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.393.g34dc348eaf-goog Subject: [PATCH v6 07/15] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland Cc: Dave Martin , Kees Cook , Laura Abbott , 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 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); -- 2.24.0.393.g34dc348eaf-goog