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50709576d8
Add a separate documentation directory for TEE subsystem since it is a standalone subsystem which already offers devices consumed by multiple different subsystem drivers. Split overall TEE subsystem documentation modularly where: - The userspace API has been moved to Documentation/userspace-api/tee.rst. - The driver API has been moved to Documentation/driver-api/tee.rst. - The first module covers the overview of TEE subsystem. - The further modules are dedicated to different TEE implementations like: - OP-TEE - AMD-TEE - and so on for future TEE implementation support. Acked-by: Rijo Thomas <Rijo-john.Thomas@amd.com> Acked-by: Jens Wiklander <jens.wiklander@linaro.org> Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20231128072352.866859-1-sumit.garg@linaro.org
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1.6 KiB
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40 lines
1.6 KiB
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.. SPDX-License-Identifier: GPL-2.0
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.. tee:
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==================================================
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TEE (Trusted Execution Environment) Userspace API
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==================================================
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include/uapi/linux/tee.h defines the generic interface to a TEE.
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User space (the client) connects to the driver by opening /dev/tee[0-9]* or
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/dev/teepriv[0-9]*.
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- TEE_IOC_SHM_ALLOC allocates shared memory and returns a file descriptor
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which user space can mmap. When user space doesn't need the file
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descriptor any more, it should be closed. When shared memory isn't needed
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any longer it should be unmapped with munmap() to allow the reuse of
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memory.
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- TEE_IOC_VERSION lets user space know which TEE this driver handles and
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its capabilities.
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- TEE_IOC_OPEN_SESSION opens a new session to a Trusted Application.
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- TEE_IOC_INVOKE invokes a function in a Trusted Application.
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- TEE_IOC_CANCEL may cancel an ongoing TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE.
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- TEE_IOC_CLOSE_SESSION closes a session to a Trusted Application.
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There are two classes of clients, normal clients and supplicants. The latter is
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a helper process for the TEE to access resources in Linux, for example file
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system access. A normal client opens /dev/tee[0-9]* and a supplicant opens
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/dev/teepriv[0-9].
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Much of the communication between clients and the TEE is opaque to the
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driver. The main job for the driver is to receive requests from the
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clients, forward them to the TEE and send back the results. In the case of
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supplicants the communication goes in the other direction, the TEE sends
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requests to the supplicant which then sends back the result.
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