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=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 2607CC35E04 for ; Tue, 25 Feb 2020 17:39:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0CD22176D for ; Tue, 25 Feb 2020 17:39:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="EyPcT46l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730246AbgBYRj5 (ORCPT ); Tue, 25 Feb 2020 12:39:57 -0500 Received: from mail-qt1-f201.google.com ([209.85.160.201]:41514 "EHLO mail-qt1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730704AbgBYRjz (ORCPT ); Tue, 25 Feb 2020 12:39:55 -0500 Received: by mail-qt1-f201.google.com with SMTP id z25so263245qto.8 for ; Tue, 25 Feb 2020 09:39:53 -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=0f/RzoyEatytyatThC+F3eOfN2v+QCCQ4NfkPjtyieo=; b=EyPcT46lQh9aSHtmCQLytlqbk6ZyOPPLjYX5wx5scKW+7DdNTGkOrtr8WuC5C5A+kK M2BFBAAJx6JVs3WDRKsHQLLRO9BpOo3t8S+EeXvYD98qVLGaIk4n8lhxVg48BDxFZjs5 Nc6k34FDhn5xt3oOYDagP97Jkr+plBtRe7++kD55djqzKodwN+PGU4IxKwvZGNmFBXDd 8QcN5Mdz8zndha20IVl5BB1PTfJZ9LIAOFGvbOHNSUOX3dDBBKVjDDteDI9+2tlyB8v+ Ocw5Df3CWfNU1rJlsPH4eLU/NoQ8/uHEpJR3GieaNAhgxd6/Vv7NFoxf5lF0teYb4qv/ fWJQ== 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=0f/RzoyEatytyatThC+F3eOfN2v+QCCQ4NfkPjtyieo=; b=NYNbNnHpWfB0w1tySigTC3wkoU2TDVFeUTh4CgnYUkDbxM0HM+YBoxYDL6Q1OOdVrd LGoV3h8D8Zzo4yMN4MfHA1oQPOuRZ8CLLG6HpDXNOVD83WkGSl6weyK7wPTOLo/4NWbB wv4Uxejwnqcjdy6w/8QI89j7f2c1VKlZEiekjBIEIdkh3Q/OXZEfnVE8oxEyeOj5yOvK 8UuJZyyodZfTUxQeGsMxTSMTrx4HgNRBJuNTo69CrGeLzrienmkMt2GLiH5ZNu++b/q+ S+gFZVwMJZjZm0ORgfjNd6Se5hog1paOatwVuIq+I4l7TTlaxoj1H98wvJYAxPVS8Cl+ 8zmQ== X-Gm-Message-State: APjAAAXTauzEqHcwW4lXqYEgonRmLtFbTQVF17k81OL4XnB18rMDzvh6 T1ukLgZZt+Z8OCu5UErDeWtVUn23LE0LZan/2J8= X-Google-Smtp-Source: APXvYqx4xojoNdX1jmjAi/7s33/U+0mXVBajNtGJvXPQGE5mjpgdpP3ETPZQPfufHi2tnyRoYGFEBUq0dG+s+BS43pM= X-Received: by 2002:a05:6214:1874:: with SMTP id eh20mr53245231qvb.122.1582652393129; Tue, 25 Feb 2020 09:39:53 -0800 (PST) Date: Tue, 25 Feb 2020 09:39:24 -0800 In-Reply-To: <20200225173933.74818-1-samitolvanen@google.com> Message-Id: <20200225173933.74818-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200225173933.74818-1-samitolvanen@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v9 03/12] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , James Morse , 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); -- 2.25.0.265.gbab2e86ba0-goog