From patchwork Fri Apr 1 10:46:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Wiklander X-Patchwork-Id: 64845 Delivered-To: patches@linaro.org Received: by 10.112.199.169 with SMTP id jl9csp658276lbc; Fri, 1 Apr 2016 03:47:29 -0700 (PDT) X-Received: by 10.112.141.73 with SMTP id rm9mr1562381lbb.57.1459507641692; Fri, 01 Apr 2016 03:47:21 -0700 (PDT) Return-Path: Received: from mail-lb0-x22c.google.com (mail-lb0-x22c.google.com. [2a00:1450:4010:c04::22c]) by mx.google.com with ESMTPS id dw8si7886506lbc.59.2016.04.01.03.47.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Apr 2016 03:47:21 -0700 (PDT) Received-SPF: pass (google.com: domain of jens.wiklander@linaro.org designates 2a00:1450:4010:c04::22c as permitted sender) client-ip=2a00:1450:4010:c04::22c; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org; spf=pass (google.com: domain of jens.wiklander@linaro.org designates 2a00:1450:4010:c04::22c as permitted sender) smtp.mailfrom=jens.wiklander@linaro.org; dmarc=pass (p=NONE dis=NONE) header.from=linaro.org Received: by mail-lb0-x22c.google.com with SMTP id vo2so69567136lbb.1 for ; Fri, 01 Apr 2016 03:47:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=30HD6uLbB9X+3nTpL5wqsPUhdCUYiIzgtu6jyKZhf4Y=; b=bqrq5J/ZBYNGJW6UT3pmcxkCLe3jTe+SzTZTzEeh+K3SlmLdlgamFTp0YFVAvic38t a4t/Tl7HKcInNoZa1lCBsMVh/xRtDpbMoe7DtF8Jvpbx9pfXfcY+fzw8LFe+aWc6UZJP 8JXOqYqqISR3JAVfwsH3yPA5q54wSphH+/ETE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=30HD6uLbB9X+3nTpL5wqsPUhdCUYiIzgtu6jyKZhf4Y=; b=XvgHBMs9Vh5C0bKp06FS97pTNgngQuIhksfsmR5cfEM9a1uJfT9AKnejgx7Fu6Ujqf 6On3kJY1KWv6xIJ4RmMuAx4ZwiQl97oXAB+mmwl3rubkgX6ziY9ItO4HJzT+xFvlCknk pZP6zW2t6y+C78HnNJdkbN9+i6u0o8RkXM/JfpeW6kklc7GC/J4UBUplGCxIqyYewmb5 bIfdHsmoLiNYgLw2jzq4pju5L6LdVDT1Qe0etq5yq1JHVx5JW53SYCVkEpa9eJQ5GvwP 7A4ZsLEXQe4E43TBfWQYyHnLJ7vMggp5edz0RxjmDdLZhsYvemGL4V6XeletUXq3/zsN AGDQ== X-Gm-Message-State: AD7BkJJRIVFcJ+Gm+aC8uXEulTxd9ZLkX7uqhWUbXtQxUX29y7anDfcCsh3/6oSeF07Y7y6n0gU= X-Received: by 10.112.130.74 with SMTP id oc10mr2351089lbb.14.1459507641501; Fri, 01 Apr 2016 03:47:21 -0700 (PDT) Return-Path: Received: from ermac.ideon.se ([85.235.10.227]) by smtp.gmail.com with ESMTPSA id o10sm1999297lbp.47.2016.04.01.03.47.19 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 01 Apr 2016 03:47:20 -0700 (PDT) From: Jens Wiklander To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org Cc: Greg Kroah-Hartman , Al Viro , Andreas Dannenberg , valentin.manea@huawei.com, jean-michel.delorme@st.com, emmanuel.michel@st.com, javier@javigon.com, Jason Gunthorpe , Mark Rutland , Michal Simek , Rob Herring , Will Deacon , Arnd Bergmann , Jens Wiklander Subject: [PATCH v9 4/4] Documentation: tee subsystem and op-tee driver Date: Fri, 1 Apr 2016 12:46:48 +0200 Message-Id: <1459507608-26582-5-git-send-email-jens.wiklander@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1459507608-26582-1-git-send-email-jens.wiklander@linaro.org> References: <1459507608-26582-1-git-send-email-jens.wiklander@linaro.org> Acked-by: Andreas Dannenberg Signed-off-by: Jens Wiklander --- Documentation/00-INDEX | 2 + Documentation/tee.txt | 118 +++++++++++++++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 121 insertions(+) create mode 100644 Documentation/tee.txt -- 1.9.1 diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index cd077ca..bd3f803 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -435,6 +435,8 @@ sysrq.txt - info on the magic SysRq key. target/ - directory with info on generating TCM v4 fabric .ko modules +tee.txt + - info on the TEE subsystem and drivers this_cpu_ops.txt - List rationale behind and the way to use this_cpu operations. thermal/ diff --git a/Documentation/tee.txt b/Documentation/tee.txt new file mode 100644 index 0000000..7185993 --- /dev/null +++ b/Documentation/tee.txt @@ -0,0 +1,118 @@ +TEE subsystem +This document describes the TEE subsystem in Linux. + +A TEE (Trusted Execution Environment) is a trusted OS running in some +secure environment, for example, TrustZone on ARM CPUs, or a separate +secure co-processor etc. A TEE driver handles the details needed to +communicate with the TEE. + +This subsystem deals with: + +- Registration of TEE drivers + +- Managing shared memory between Linux and the TEE + +- Providing a generic API to the TEE + +The TEE interface +================= + +include/uapi/linux/tee.h defines the generic interface to a TEE. + +User space (the client) connects to the driver by opening /dev/tee[0-9]* or +/dev/teepriv[0-9]*. + +- TEE_IOC_SHM_ALLOC allocates shared memory and returns a file descriptor + which user space can mmap. When user space doesn't need the file + descriptor any more, it should be closed. When shared memory isn't needed + any longer it should be unmapped with munmap() to allow the reuse of + memory. + +- TEE_IOC_VERSION lets user space know which TEE this driver handles and + the its capabilities. + +- TEE_IOC_OPEN_SESSION opens a new session to a Trusted Application. + +- TEE_IOC_INVOKE invokes a function in a Trusted Application. + +- TEE_IOC_CANCEL may cancel an ongoing TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE. + +- TEE_IOC_CLOSE_SESSION closes a session to a Trusted Application. + +There are two classes of clients, normal clients and supplicants. The latter is +a helper process for the TEE to access resources in Linux, for example file +system access. A normal client opens /dev/tee[0-9]* and a supplicant opens +/dev/teepriv[0-9]. + +Much of the communication between clients and the TEE is opaque to the +driver. The main job for the driver is to receive requests from the +clients, forward them to the TEE and send back the results. In the case of +supplicants the communication goes in the other direction, the TEE sends +requests to the supplicant which then sends back the result. + +OP-TEE driver +============= + +The OP-TEE driver handles OP-TEE [1] based TEEs. Currently it is only the ARM +TrustZone based OP-TEE solution that is supported. + +Lowest level of communication with OP-TEE builds on ARM SMC Calling +Convention (SMCCC) [2], which is the foundation for OP-TEE's SMC interface +[3] used internally by the driver. Stacked on top of that is OP-TEE Message +Protocol [4]. + +OP-TEE SMC interface provides the basic functions required by SMCCC and some +additional functions specific for OP-TEE. The most interesting functions are: + +- OPTEE_SMC_FUNCID_CALLS_UID (part of SMCCC) returns the version information + which is then returned by TEE_IOC_VERSION + +- OPTEE_SMC_CALL_GET_OS_UUID returns the particular OP-TEE implementation, used + to tell, for instance, a TrustZone OP-TEE apart from an OP-TEE running on a + separate secure co-processor. + +- OPTEE_SMC_CALL_WITH_ARG drives the OP-TEE message protocol + +- OPTEE_SMC_GET_SHM_CONFIG lets the driver and OP-TEE agree on which memory + range to used for shared memory between Linux and OP-TEE. + +The GlobalPlatform TEE Client API [5] is implemented on top of the generic +TEE API. + +Picture of the relationship between the different components in the +OP-TEE architecture. + + User space Kernel Secure world + ~~~~~~~~~~ ~~~~~~ ~~~~~~~~~~~~ + +--------+ +-------------+ + | Client | | Trusted | + +--------+ | Application | + /\ +-------------+ + || +----------+ /\ + || |tee- | || + || |supplicant| \/ + || +----------+ +-------------+ + \/ /\ | TEE Internal| + +-------+ || | API | + + TEE | || +--------+--------+ +-------------+ + | Client| || | TEE | OP-TEE | | OP-TEE | + | API | \/ | subsys | driver | | Trusted OS | + +-------+----------------+----+-------+----+-----------+-------------+ + | Generic TEE API | | OP-TEE MSG | + | IOCTL (TEE_IOC_*) | | SMCCC (OPTEE_SMC_CALL_*) | + +-----------------------------+ +------------------------------+ + +RPC (Remote Procedure Call) are requests from secure world to kernel driver +or tee-supplicant. An RPC is identified by a special range of SMCCC return +values from OPTEE_SMC_CALL_WITH_ARG. RPC messages which are intended for the +kernel are handled by the kernel driver. Other RPC messages will be forwarded to +tee-supplicant without further involvement of the driver, except switching +shared memory buffer representation. + +References: +[1] https://github.com/OP-TEE/optee_os +[2] http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html +[3] drivers/tee/optee/optee_smc.h +[4] drivers/tee/optee/optee_msg.h +[5] http://www.globalplatform.org/specificationsdevice.asp look for + "TEE Client API Specification v1.0" and click download. diff --git a/MAINTAINERS b/MAINTAINERS index e47bed3..8758be5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9758,6 +9758,7 @@ S: Maintained F: include/linux/tee_drv.h F: include/uapi/linux/tee.h F: drivers/tee/ +F: Documentation/tee.txt THUNDERBOLT DRIVER M: Andreas Noever