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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=+oBtFp6IQZ5946CFExp5BXllfwypP5AUtOYhvu+6eDg=; b=dYhVWLcjv4MNulWPZOc+lL9z4cfFXSq72rc4oli5v9KvW/U3M6B4ZhQGfZ3O835TxW C38IiLS65v3Jc1GfcToS1VNxd5++SB/zjO9dq0+C9WTHwhIWBS8CQNJtP3FQ4lRyWaQ3 MKZkb1gTbDcVaPpV2kL6tgCGhC6AxwbSCr/JWyJd5otvWWaK6brA3OZnzzQHLNEGRkZ9 CxkP4nCwIigUeaGyCw77sxKYEelHcLgTrcxpMjTO5EH8+eMPpQAMvCUp8oIK6+efEA0m 8Byh8yNy7x41VI8PU9AhNvZsaSuYQ3oRjzddcrISwOjrq/tY3IXiPMHnutFs2qFVqFa4 6k0Q== X-Gm-Message-State: APjAAAUgMolb2IdqcE4KxfS6B3Eby/bG0IzF8L2Do0jtGNT+Js/yNo1n vZ2Y9b8TY73ojekaYDl6opQcur4xW9qYuNLohcM= X-Google-Smtp-Source: APXvYqxHqmmpD11MJRO6yuoyBvltYKFWJkQq7UxJVT4qvc6swUR9mDIPTvziXaDvcDGhe+mECq8Qr7PX0sGP/3daZE0= X-Received: by 2002:a63:7845:: with SMTP id t66mr10836733pgc.31.1571415070584; Fri, 18 Oct 2019 09:11:10 -0700 (PDT) Date: Fri, 18 Oct 2019 09:10:23 -0700 In-Reply-To: <20191018161033.261971-1-samitolvanen@google.com> Message-Id: <20191018161033.261971-9-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> X-Mailer: git-send-email 2.23.0.866.gb869b98d4c-goog Subject: [PATCH 08/18] scs: add support for stack usage debugging From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191018_171141_014005_B8ED8463 X-CRM114-Status: GOOD ( 11.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Kees Cook , kernel-hardening@lists.openwall.com, Nick Desaulniers , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Sami Tolvanen , Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.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 0e3cba49ea1a..1ec5c5a8dfae 100644 --- a/kernel/scs.c +++ b/kernel/scs.c @@ -161,6 +161,44 @@ 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; @@ -175,6 +213,7 @@ 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); -- 2.23.0.866.gb869b98d4c-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel