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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=Ummeb//L4UGzSQ9YmLkDAY3kIJvHpvVlDZif3GsciVU=; b=UdmyeHEzutk3ZLjJp+oPOQEUAih9itvfc2jG8MV3moDDkPQ/7+7Lj/08fmzU9dKAvI PH7n4frwwdEFkSBd9Nj51r3CRVovT1UBakqiTb06gXE+bGQUjAq/lvo+h7tPaRBtRWed ZhU2l42kNLVlyu3NhVOUcSeeAhT4jX234oGID1KWBIi+5dr+5+1hOaXDeL2QPJ86ou92 PUQvqHXuxyOzEe7xYnsnoezrDcauUUzs1OT/BUVOxqJYMBbELqHKJ1o6SThcA6iPsnm9 jpokJQoEwO80R9u2jxF91oiVC111mBIK6hPYTtzpMFrTYKxEXeVMgoxhVVVHjQzcVuPA ttwg== X-Gm-Message-State: AGi0PuZDQNOhBggTWov8CTh/4l75BKvW0AoUyzZISxEErn+O9FX1bcu6 NIA9CpIqrfUYeB0Pz+Lz83rnIVeYQvCFvtkhl+0= X-Google-Smtp-Source: APiQypLfMllChVStp0nVVJRc46ooIEmPC5lxhHr5UbQWQtwRSJW5jYCIR/c33rb1nlAjMKVaAFGW/fG0jdBYpJoZ1PU= X-Received: by 2002:a17:90a:20f0:: with SMTP id f103mr196700pjg.88.1586191297993; Mon, 06 Apr 2020 09:41:37 -0700 (PDT) Date: Mon, 6 Apr 2020 09:41:12 -0700 In-Reply-To: <20200406164121.154322-1-samitolvanen@google.com> Message-Id: <20200406164121.154322-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200406164121.154322-1-samitolvanen@google.com> X-Mailer: git-send-email 2.26.0.292.g33ef6b2f38-goog Subject: [PATCH v10 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200406_094140_941238_7889E03D X-CRM114-Status: UNSURE ( 9.92 ) X-CRM114-Notice: Please train this message. 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: Kees Cook , Jann Horn , Masahiro Yamada , Marc Zyngier , kernel-hardening@lists.openwall.com, Nick Desaulniers , linux-kernel@vger.kernel.org, Miguel Ojeda , 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. 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); -- 2.26.0.292.g33ef6b2f38-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel