diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/00-INDEX | 2 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt | 31 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/vendor-prefixes.txt | 1 | ||||
| -rw-r--r-- | Documentation/ioctl/ioctl-number.txt | 1 | ||||
| -rw-r--r-- | Documentation/tee.txt | 118 |
5 files changed, 153 insertions, 0 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index 793acf999e9e..ed3e5e949fce 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -412,6 +412,8 @@ sysctl/ - directory with info on the /proc/sys/* files. 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/devicetree/bindings/arm/firmware/linaro,optee-tz.txt b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt new file mode 100644 index 000000000000..d38834c67dff --- /dev/null +++ b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt @@ -0,0 +1,31 @@ +OP-TEE Device Tree Bindings + +OP-TEE is a piece of software using hardware features to provide a Trusted +Execution Environment. The security can be provided with ARM TrustZone, but +also by virtualization or a separate chip. + +We're using "linaro" as the first part of the compatible property for +the reference implementation maintained by Linaro. + +* OP-TEE based on ARM TrustZone required properties: + +- compatible : should contain "linaro,optee-tz" + +- method : The method of calling the OP-TEE Trusted OS. Permitted + values are: + + "smc" : SMC #0, with the register assignments specified + in drivers/tee/optee/optee_smc.h + + "hvc" : HVC #0, with the register assignments specified + in drivers/tee/optee/optee_smc.h + + + +Example: + firmware { + optee { + compatible = "linaro,optee-tz"; + method = "smc"; + }; + }; diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt index f9fe94535b46..12e27844bb7b 100644 --- a/Documentation/devicetree/bindings/vendor-prefixes.txt +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt @@ -173,6 +173,7 @@ lego LEGO Systems A/S lenovo Lenovo Group Ltd. lg LG Corporation licheepi Lichee Pi +linaro Linaro Limited linux Linux-specific binding lltc Linear Technology Corporation lsi LSI Corp. (LSI Logic) diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt index eccb675a2852..1e9fcb4d0ec8 100644 --- a/Documentation/ioctl/ioctl-number.txt +++ b/Documentation/ioctl/ioctl-number.txt @@ -309,6 +309,7 @@ Code Seq#(hex) Include File Comments 0xA3 80-8F Port ACL in development: <mailto:tlewis@mindspring.com> 0xA3 90-9F linux/dtlk.h +0xA4 00-1F uapi/linux/tee.h Generic TEE subsystem 0xAA 00-3F linux/uapi/linux/userfaultfd.h 0xAB 00-1F linux/nbd.h 0xAC 00-1F linux/raw.h diff --git a/Documentation/tee.txt b/Documentation/tee.txt new file mode 100644 index 000000000000..718599357596 --- /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. |