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 21B07C5DF61 for ; Tue, 5 Nov 2019 23:56:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C116B21A49 for ; Tue, 5 Nov 2019 23:56:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TKd2so4t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387509AbfKEX4h (ORCPT ); Tue, 5 Nov 2019 18:56:37 -0500 Received: from mail-pl1-f201.google.com ([209.85.214.201]:48287 "EHLO mail-pl1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387453AbfKEX4g (ORCPT ); Tue, 5 Nov 2019 18:56:36 -0500 Received: by mail-pl1-f201.google.com with SMTP id t5so12057883plz.15 for ; Tue, 05 Nov 2019 15:56:35 -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=rtGYhrlT+v4glRCgBr5KwA8OmlbDFJXwY4ztX1r8N4Y=; b=TKd2so4t7KdR/7IGrMM7dl1XICyaB7Ep2xb2K+L1YFpFhAdGCuA+QVKoOX+2nBhRS1 PbhJFwrDkZsuR4g7Ll5jibhYYSoSbj6Qsk2MbBrD3K/3RVFYn3Ze4sq2kV7P6t82dOWN zANq01dIUJjLIJAHUFq7xMVXaYxiN41idA7UoNEeJpkXFp/ZWlp+zSbMC4BIJqBb48KR 4Yz6i7rx8RTibsrTijP0CrOXXl43bw03Swi1hDDM7ENVWaU1ch5tyPwrarZdzghv3p22 6EIfdhBRrf+kmU4AHHY+5aG/aq0yLasD+4SyCQWE2lPdStxSTwo8liAyHr/FcLSygxFM ArVQ== 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=rtGYhrlT+v4glRCgBr5KwA8OmlbDFJXwY4ztX1r8N4Y=; b=VrjQ1NVEivxoHUvL3U2siRplFWC1kB7YOWRQkhk4bCQ+3tsdxSGwU70NbXyzW0GeD/ qtK1O4BZZwxMQjpmv3A7nj4Pqxs8mbTBI9PLvkkwc9laXxZD8r1CHRiMiEA1+j/IgFK9 ghzSTWfMwxMhlDCHPU67xU9Gt4ziz2sggKivBq7hneGORukKwVnKu0Os5tWZGKb2lqTF Bm8XFk/WMy6PJLEp1pPCAo0zhUP7r0uNEzzIlp9/ixBaGsNUF9CRPMNybxRv8OB/p6yN JsWkuOeI0Jrqdcg8i/PSe/H0IAcHDMi6SgaCkQY14RT8GCfOvri+/WbvfhGOhV2Hhuym UrhA== X-Gm-Message-State: APjAAAWR/9nYcEcgrk/szmnUlKMtL24nLxnYsP9bW4vNJucSH2gnCDEe hi8RNa6txZVd6sHMrz9nR6p/xEouVNvwnkAY1LM= X-Google-Smtp-Source: APXvYqyeiXNhg0SMmYGCzlPE1MJNPVlZmSKCnBjsXssOcDuiJaeCfp0JdeBqZLhwpNQMgciNZVJzMgpXUPeRRsEDFOQ= X-Received: by 2002:a65:6149:: with SMTP id o9mr5335991pgv.228.1572998195111; Tue, 05 Nov 2019 15:56:35 -0800 (PST) Date: Tue, 5 Nov 2019 15:56:01 -0800 In-Reply-To: <20191105235608.107702-1-samitolvanen@google.com> Message-Id: <20191105235608.107702-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191105235608.107702-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.rc1.363.gb1bccd3e3d-goog Subject: [PATCH v5 07/14] 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 Reviewed-by: Kees Cook --- kernel/scs.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/kernel/scs.c b/kernel/scs.c index 4f5774b6f27d..a47fae33efdc 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.rc1.363.gb1bccd3e3d-goog