- OP-TEE - lists.trustedfirmware.org

[PATCH v2] Documentation: Extend the real-time hardware bits with some firmware bits

by Sebastian Andrzej Siewior

I have been reviewing how OP‑TEE is implemented and how secure‑world invocations behave. The goal was to determine whether an OP‑TEE call can delay the Linux side and introduce latency depending on the time spent in the secure world. Similar latency effects are already known for EFI runtime services, but this was not documented. To mitigate the impact, EFI runtime invocations can be restricted to specific CPUs so that real‑time workloads on other CPUs remain unaffected. This mechanism, however, is only described in the commit that introduced it. This change adds a firmware section that documents these behaviours explicitly. It highlights cases where firmware can delay the kernel, information that may be unfamiliar to some users and surprising-or concerning-to others. Assisted-by: Microsoft-Copilot Signed-off-by: Sebastian Andrzej Siewior <bigeasy(a)linutronix.de> --- v1…v2: https://lore.kernel.org/all/20260701091226.7SWW4TrT@linutronix.de - Rewrote the OP-TEE bits after some feedback from Ilias and Jens. Added a link to the TF-A/OP-TEE documentation. The main difference is that in contrast to my initial belief, OP-TEE can disable normal-world's interrupts and it is not guaranteed that normal world can always preempt the secure world. Documentation/core-api/real-time/hardware.rst | 104 ++++++++++++++++++ 1 file changed, 104 insertions(+) diff --git a/Documentation/core-api/real-time/hardware.rst b/Documentation/core-api/real-time/hardware.rst index 19f9bb3786e03..9f95e75e6aa18 100644 --- a/Documentation/core-api/real-time/hardware.rst +++ b/Documentation/core-api/real-time/hardware.rst @@ -130,3 +130,107 @@ https://github.com/Linutronix/RTC-Testbench. The goal of this project is to validate real-time network communication. It can be thought of as a "cyclictest" for networking and also serves as a starting point for application development. + +Firmware +-------- + +The firmware often plays a significant role in system operation because it can +perform tasks that the kernel cannot directly access, and in some cases it can +even preempt or intercept the kernel. + +A common example of firmware assisting the kernel is when it provides a generic +interface to a resource. Instead of accessing an RTC chip through an I2C host +controller, the kernel may query the firmware for the current time, and the +firmware then accesses the RTC behind the scenes. + +Firmware can also intercept kernel execution by providing services that +temporarily take control of the system. One example is memory scrubbing, where +the firmware periodically pauses the kernel, reads back portions of system +memory, and then returns control. During this time, the kernel is effectively +interrupted. +In contrast, some systems provide hardware-based memory scrubbing, which +operates independently of firmware or software. See +Documentation/edac/scrub.rst for details. + +If the kernel is intercepted for longer periods then these periods can be made +visible with the hardware latency detector. See +Documentation/trace/hwlat_detector.rst. + +The kernel can also be intercepted in response to specific events, such as +overheating. In this case, the firmware may throttle the CPU or shut it down +immediately to prevent hardware damage. + +Unless the firmware is well documented, it should be thoroughly tested to +uncover any unexpected behaviour. + +EFI +~~~~ + +EFI provides runtime services that act as a communication interface between the +firmware and the operating system. One such service is reading and writing EFI +variables, which are used, for example, to determine the boot source. + +Invoking a runtime service may require the architecture to disable kernel +preemption or interrupts during the call. This means the duration of a service +invocation directly affects the system’s observable latency. There is also +nothing that prevents a service call from disabling interrupts internally while +it runs. + +For these reasons, EFI runtime services are disabled by default on a PREEMPT_RT +kernel. They can still be enabled at boot time or via a Kconfig option if +required. +The native EFI runtime service implementation (where both the EFI service and +the kernel are either 32-bit or 64-bit executables) uses a wrapper mechanism +that invokes the service through a dedicated workqueue. This workqueue is named +efi_runtime, and it can be restricted to a housekeeping CPU using the +``/sys/devices/virtual/workqueue/efi_runtime/cpumask`` sysfs file. Assigning it +to a housekeeping CPU ensures that potentially long service invocations do not +impact the real-time workload which is restricted to other CPUs. + +It must also be verified that the runtime services behave as expected. Some +implementations on the x86 architecture pause all other CPUs while one CPU +performs the service call. In such cases, the interruption affects all CPUs, +and restricting the workqueue to a single CPU provides no benefit. + +OP-TEE (ARM) +~~~~~~~~~~~~ + +Execution flows from the normal world (Linux) into the secure world (OP-TEE) +through the secure monitor at EL3. The transition is initiated by the `smc` +(Secure Monitor Call) opcode or the `hvc` (Hypervisor Call) opcode together +with a function identifier. The calling convention defines two types of calls: +**yielding calls** and **fast calls**: + +- A **yielding call** unmasks interrupts before handling the requested service, + allowing normal world interrupts to occur. +- A **fast call** handles the requested service atomically, without allowing + interrupts from either the normal world or the secure world. + +In addition, the secure world (EL3 and OP-TEE) can receive interrupts routed to +the secure world. While a secure world interrupt is being serviced, +normal world interrupts are masked and cannot preempt the operation. + +The transition from normal world to secure monitor to OP-TEE and back introduces +additional latency due to world switching and context save/restore. This +overhead is typically a few microseconds and usually remains within the noise +floor. + +It is worth noting that the normal world cannot mask secure interrupts, while +the secure world can mask normal-world interrupts during execution. How OP-TEE +affects real-time workloads depends on whether secure interrupts are enabled +and which OP-TEE services are invoked. + +A practical concern is any fast call that runs longer than expected, for +example a function that occasionally performs a long-running cryptographic +computation. Another example that may block in an unexpected way are OP-TEE +drivers that issue RPC requests. An OP-TEE service in the secure world (RPMB +for instance) may need to issue a request back to the normal world (the Linux +driver) in order to complete the operation. While Linux remains preemptible, +the thread that issued the request stays blocked until the RPC completes and +the secure function call returns. + +The TF-A project provides documentation on interrupt management: +https://trustedfirmware-a.readthedocs.io/en/latest/design/interrupt-framework-design.html#interrupt-management-framework + +The OP-TEE project provides documentation on how interrupts are handled: +https://optee.readthedocs.io/en/latest/architecture/core.html#interrupt-handling -- 2.53.0

1 month, 2 weeks

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[GIT PULL] QCOMTEE update for v7.3

by Jens Wiklander

Hello soc maintainers, Please pull this small update for the QCOMTEE driver. Thanks, Jens The following changes since commit dc59e4fea9d83f03bad6bddf3fa2e52491777482: Linux 7.2-rc1 (2026-06-28 12:01:31 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/qcomtee-for-v7.3 for you to fetch changes up to d92f87f3e7c79f58cc6d6edad4bf1c96f795aa7b: tee: qcomtee: Drop unused assignment of platform_device_id driver data (2026-06-29 07:53:26 +0200) ---------------------------------------------------------------- Drop unused assignment of platform_device_id driver data ---------------------------------------------------------------- Uwe Kleine-König (The Capable Hub) (1): tee: qcomtee: Drop unused assignment of platform_device_id driver data drivers/tee/qcomtee/call.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

1 month, 3 weeks

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[GIT PULL] OP-TEE fix for v7.2

by Jens Wiklander

Hello soc maintainers, Please pull this small OP-TEE fix for the OP-TEE drivers. Thanks, Jens The following changes since commit dc59e4fea9d83f03bad6bddf3fa2e52491777482: Linux 7.2-rc1 (2026-06-28 12:01:31 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jenswi/linux-tee.git tags/optee-fix-for-v7.2 for you to fetch changes up to 650c88738ae8976f46ba71b24dd8aa311adc6fde: optee: ffa: Add NULL check in optee_ffa_lend_protmem (2026-06-29 08:04:45 +0200) ---------------------------------------------------------------- Add NULL check in optee_ffa_lend_protmem() ---------------------------------------------------------------- Mostafa Saleh (1): optee: ffa: Add NULL check in optee_ffa_lend_protmem drivers/tee/optee/ffa_abi.c | 3 +++ 1 file changed, 3 insertions(+)

1 month, 3 weeks

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[PATCH] tee: avoid accessing dma-buf shared memory after put

by Hongyan Xu

param_from_user_memref() obtains a temporary reference to the dma-buf tee_shm wrapper by ID. If closing the shared-memory file descriptor races with the ioctl, this temporary reference can be the wrapper's last one. tee_shm_put() then frees the enclosing tee_shm_dmabuf_ref, but the function still reads ref->parent_shm and ref->offset afterwards. Save the parent pointer and offset before dropping the wrapper reference. The additional parent reference keeps the parent shared memory alive for the parameter list as before. Fixes: 146bf4e75eca ("tee: new ioctl to a register tee_shm from a dmabuf file descriptor") Cc: stable(a)vger.kernel.org Signed-off-by: Hongyan Xu <getshell(a)seu.edu.cn> --- drivers/tee/tee_core.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 1aac50c7c1de..489c39d5b35f 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -397,6 +397,7 @@ static int param_from_user_memref(struct tee_context *ctx, } if (shm->flags & TEE_SHM_DMA_BUF) { + struct tee_shm *parent_shm; struct tee_shm_dmabuf_ref *ref; ref = container_of(shm, struct tee_shm_dmabuf_ref, shm); @@ -409,10 +410,11 @@ static int param_from_user_memref(struct tee_context *ctx, * list instead of the shm we got with * tee_shm_get_from_id() above. */ - refcount_inc(&ref->parent_shm->refcount); - tee_shm_put(shm); - shm = ref->parent_shm; + parent_shm = ref->parent_shm; offs = ref->offset; + refcount_inc(&parent_shm->refcount); + tee_shm_put(shm); + shm = parent_shm; } } } else if (ctx->cap_memref_null) { -- 2.50.1.windows.1

1 month, 3 weeks

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ufs: rpmb: make RPMB usable with OP-TEE key derivation

by Jorge Ramirez-Ortiz

This series makes UFS RPMB work out of the box with an OP-TEE that implements the standard eMMC RPMB key-derivation flow, without requiring any fundamental changes on the OP-TEE side. RPMB provides an authenticated, replay-protected storage area whose security relies on a secret authentication key. In our setup that key is never exposed to the kernel: OP-TEE derives it in the secure world from its hardware-unique key and a device identifier (dev_id) that the RPMB core hands down. OP-TEE's implementation targets eMMC, where dev_id is the 16-byte eMMC CID, and both the fixed length and the raw-CID layout are baked into its key derivation. Two things stand in the way of reusing that same, unmodified OP-TEE flow for UFS RPMB: 1. On a cold boot the very first frame sent to the RPMB well-known LU comes back with a power-on UNIT ATTENTION (ASC 0x29), which the SCSI core reports rather than retries. RPMB has no earlier guaranteed access that could clear the condition first, so RPMB fails on every power cycle. Patch 1 asks the SCSI core to retry the power-on UNIT ATTENTION on the RPMB WLUN. 2. The UFS RPMB id is "<device_id>-R<region>", which is variable length and longer than 16 bytes. Passing it verbatim would tie the derived key to a length OP-TEE does not expect and diverge from the fixed eMMC CID ABI. Patch 2 hashes it into a fixed 16-byte dev_id with blake2s, keeping the key stable and unique per region while matching the eMMC CID layout OP-TEE relies on. The hash algorithm and input string are thus part of the key-derivation ABI and must stay stable. With both patches, UFS RPMB is functional from the first access after a cold boot and derives keys through the existing eMMC-style OP-TEE flow, (requires minimal OP-TEE changes). Jorge Ramirez-Ortiz (2): ufs: rpmb: retry power-on UNIT ATTENTION on the RPMB WLUN ufs: rpmb: use a fixed-length RPMB dev_id drivers/ufs/Kconfig | 1 + drivers/ufs/core/ufs-rpmb.c | 41 ++++++++++++++++++++++++++++++++++--- 2 files changed, 39 insertions(+), 3 deletions(-)

1 month, 3 weeks

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[PATCH v2] tee: remove TZMEM_MODE_GENERIC

by Julian Braha

'select' does not work on config options in a 'choice', so currently it is possible to enable QCOMTEE without QCOM_TZMEM_MODE_SHMBRIDGE, even though this is needed at runtime. There are no users of the generic allocator option, QCOM_TZMEM_MODE_GENERIC, so let's remove it. Then, we can remove the containing choice..endchoice, which allows the 'select' to work as intended. Suggested-by: Arnd Bergmann <arnd(a)arndb.de> Signed-off-by: Julian Braha <julianbraha(a)gmail.com> --- Changes since v1: - remove TZMEM_MODE_GENERIC instead of removing the dead select Link: https://lore.kernel.org/all/20260715092539.18384-1-julianbraha@gmail.com/ --- drivers/firmware/qcom/Kconfig | 26 +++++--------------------- drivers/firmware/qcom/qcom_tzmem.c | 21 --------------------- 2 files changed, 5 insertions(+), 42 deletions(-) diff --git a/drivers/firmware/qcom/Kconfig b/drivers/firmware/qcom/Kconfig index c7f8413ab996..d99e09c5fa18 100644 --- a/drivers/firmware/qcom/Kconfig +++ b/drivers/firmware/qcom/Kconfig @@ -34,33 +34,17 @@ config QCOM_TZMEM tristate select GENERIC_ALLOCATOR -choice - prompt "TrustZone interface memory allocator mode" - depends on QCOM_TZMEM - default QCOM_TZMEM_MODE_GENERIC - help - Selects the mode of the memory allocator providing memory buffers of - suitable format for sharing with the TrustZone. If in doubt, select - 'Generic'. - -config QCOM_TZMEM_MODE_GENERIC - bool "Generic" - help - Use the generic allocator mode. The memory is page-aligned, non-cachable - and physically contiguous. - config QCOM_TZMEM_MODE_SHMBRIDGE - bool "SHM Bridge" + bool "TrustZone interface memory allocator: SHM Bridge" + depends on QCOM_TZMEM help - Use Qualcomm Shared Memory Bridge. The memory has the same alignment as - in the 'Generic' allocator but is also explicitly marked as an SHM Bridge - buffer. + Use Qualcomm Shared Memory Bridge as memory allocator. The memory has the + same alignment as in the 'Generic' allocator but is also explicitly marked + as an SHM Bridge buffer. With this selected, all buffers passed to the TrustZone must be allocated using the TZMem allocator or else the TrustZone will refuse to use them. -endchoice - config QCOM_QSEECOM bool "Qualcomm QSEECOM interface driver" depends on QCOM_SCM=y diff --git a/drivers/firmware/qcom/qcom_tzmem.c b/drivers/firmware/qcom/qcom_tzmem.c index 0635cbeacfc8..5b3e5a3ad1ae 100644 --- a/drivers/firmware/qcom/qcom_tzmem.c +++ b/drivers/firmware/qcom/qcom_tzmem.c @@ -49,25 +49,6 @@ static struct device *qcom_tzmem_dev; static RADIX_TREE(qcom_tzmem_chunks, GFP_ATOMIC); static DEFINE_SPINLOCK(qcom_tzmem_chunks_lock); -#if IS_ENABLED(CONFIG_QCOM_TZMEM_MODE_GENERIC) - -static int qcom_tzmem_init(void) -{ - return 0; -} - -static int qcom_tzmem_init_area(struct qcom_tzmem_area *area) -{ - return 0; -} - -static void qcom_tzmem_cleanup_area(struct qcom_tzmem_area *area) -{ - -} - -#elif IS_ENABLED(CONFIG_QCOM_TZMEM_MODE_SHMBRIDGE) - #include <linux/firmware/qcom/qcom_scm.h> #include <linux/of.h> @@ -189,8 +170,6 @@ static void qcom_tzmem_cleanup_area(struct qcom_tzmem_area *area) kfree(handle); } -#endif /* CONFIG_QCOM_TZMEM_MODE_SHMBRIDGE */ - static int qcom_tzmem_pool_add_memory(struct qcom_tzmem_pool *pool, size_t size, gfp_t gfp) { -- 2.55.0

1 month, 3 weeks

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[PATCH] tee: qcomtee: user: check the parameter count from the supplicant

by HyeongJun An

The qcomtee_cb_params_to_args() walks the argument array QTEE asked for and indexes the parameter array the supplicant supplied, but it never looks at num_params. A supplicant that answers TEE_IOC_SUPPL_SEND with fewer parameters than the request needs makes that walk read past the end of the allocation. To fix this, reject a response that is too short, the way ureq_select() already does for the receive direction. Fixes: d6e290837e50 ("tee: add Qualcomm TEE driver") Assisted-by: Claude:claude-opus-5 Signed-off-by: HyeongJun An <sammiee5311(a)gmail.com> --- drivers/tee/qcomtee/user_obj.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/tee/qcomtee/user_obj.c b/drivers/tee/qcomtee/user_obj.c index 10452fcc7ccb..2a594ae299da 100644 --- a/drivers/tee/qcomtee/user_obj.c +++ b/drivers/tee/qcomtee/user_obj.c @@ -507,6 +507,10 @@ static int qcomtee_cb_params_to_args(struct qcomtee_arg *u, { int i; + /* Supplicant can not send fewer parameters than requested. */ + if (num_params < qcomtee_args_len(u)) + return -EINVAL; + qcomtee_arg_for_each(i, u) { switch (u[i].type) { case QCOMTEE_ARG_TYPE_IB: -- 2.43.0

2 months

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OP-TEE Contributions Forum, monthly meeting July 28

by Etienne CARRIERE - foss

Dear all, Tomorrow, Tuesday July 28th, 8am UTC, is the next OP-TEE Public Meeting. For time and connection details, see the calendar at: https://www.trustedfirmware.org/meetings There are no specific topics to the agenda but feel free to join and raise any question or share any topic you want, or just attend in case some discussed topics may interest you. Sorry for the short notice. Regards, Etienne Carriere

2 months

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[PATCH] tee: remove dead select from kconfig

by Julian Braha

'select' does not work on config options in a 'choice', so currently it is possible to enable QCOMTEE without QCOM_TZMEM_MODE_SHMBRIDGE. This patch removes the select. I've compile-tested this and found that it builds fine without QCOM_TZMEM_MODE_SHMBRIDGE, but I don't have the hardware to runtime test. Please advise if it would be better to make QCOM_TZMEM_MODE_SHMBRIDGE a dependency. This dead select was found by kconfirm, a static analysis tool for Kconfig. Signed-off-by: Julian Braha <julianbraha(a)gmail.com> --- drivers/tee/qcomtee/Kconfig | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/tee/qcomtee/Kconfig b/drivers/tee/qcomtee/Kconfig index 9f19dee08db4..00e07ed80138 100644 --- a/drivers/tee/qcomtee/Kconfig +++ b/drivers/tee/qcomtee/Kconfig @@ -5,7 +5,6 @@ config QCOMTEE depends on ARCH_QCOM || COMPILE_TEST depends on !CPU_BIG_ENDIAN select QCOM_SCM - select QCOM_TZMEM_MODE_SHMBRIDGE help This option enables the Qualcomm Trusted Execution Environment (QTEE) driver. It provides an API to access services offered by QTEE and -- 2.54.0

2 months, 1 week

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[PATCH 0/6] Add TEE based client driver for UEFI Secure Application

by Harshal Dev

On Qualcomm SoC based platforms, UEFI stores EFI variables within the Replay Protected Memory Block (RPMB) which is only accessible by the Qualcomm Trusted Execution Environment (QTEE). For Qualcomm platforms without emulated RPMB support, specifically platforms where RPMB is not located within SPI-NOR storage and instead located on UFS/EMMC storage, non-volatile EFI variables can only be set via a callback request from the UEFI Secure Application to the RPMB service running in user-space (within the QTEE supplicant [1]). Unlike the QCOM-TEE driver, the QSEECOM driver (used by the current QSEECOM based uefisecapp) does not support callback requests. And on certain Qualcomm platforms such as the RB3Gen2, attempts to access the QSEECOM interface fail due to lack of support within Qualcomm TEE. On these platforms, a TEE based uefisecapp client driver is required to: 1. Access cached & volatile EFI variables stored in uefisecapp's memory. 2. Ensure persistence of non-volatile EFI variables via writes through the RPMB service hosted in the QTEE supplicant. This series introduces such a uefisecapp TEE client driver for the aforementioned Qualcomm platforms which installs efi-var operations _if_ the QCOMTEE driver registers support for an object-IPC based uefisecapp service on the TEE bus during its probe. Only new QTEE firmware versions available at [2] provide this support. Thus, QCOMTEE now maintains a static list of always-available object-IPC based secure services exposed by QTEE. These services are implemented either within the QTEE kernel or within a pre-loaded Trusted Application (TA) usually loaded by the bootloader. The uefisecapp TA is an example of a preloaded TA loaded by UEFI. A static list is required since QTEE does not yet expose any way to dynamically query and enumerate the services exposed by it. To facilitate object-IPC interactions from the kernel-space, this series also introduces a tee_client_object_invoke_func() to allow invocation of TEE objects similar to the existing tee_client_invoke_func() API exported by the TEE subsystem which allows invocation of TEE functions. Some suporting changes are also introduced to track and handle operations for TEE contexts opened from the kernel-space in the back-end QCOM-TEE driver along with associated changes in user-space libqcomtee via Pull Request [3]. Finally and as previously mentioned, access to the object-IPC based uefisecapp service is restricted on older QTEE firmware versions. A new QTEE firmware release must be picked up from QArtifactory [2] for all upstream supported Qualcomm SoCs to enable access to uefisecapp service via the TEE client driver. This patch series has been validated on Kodiak RB3Gen2 platform with UFS storage by attempting to read/write EFI variables via the efivar tool [4] after mounting the efivarfs filesystem. See [5] for an example. Merge Strategy: This patch series could either be taken from the OP-TEE tree or the QCOM soc tree. I would prefer it to be picked by the OP-TEE tree since all except the uefisecapp TEE client driver patch in this series make changes relevant to the TEE subsystem. It would be great if the QCOM soc tree maintainers can Ack the uefisecapp driver patch. [1] https://github.com/qualcomm/minkipc [2] https://shorturl.at/zQU07 [3] https://github.com/quic/quic-teec/pull/27 [4] https://github.com/rhboot/efivar [5] https://docs.qualcomm.com/doc/80-70020-27/topic/manage_uefi_environment_var… Signed-off-by: Harshal Dev <harshal.dev(a)oss.qualcomm.com> --- Amirreza Zarrabi (2): tee: Add kernel client object invoke helper tee: qcomtee: Allow object invokes from kernel clients Harshal Dev (4): tee: qcomtee: Track the object invocation context tee: Export uuidv5 generation for TEE clients tee: qcomtee: Add support for registering QTEE services on TEE bus firmware: qcom: Add support for TEE based EFI-var client driver MAINTAINERS | 7 + drivers/firmware/qcom/Kconfig | 24 ++ drivers/firmware/qcom/Makefile | 1 + drivers/firmware/qcom/qcom_tee_uefisecapp.c | 525 ++++++++++++++++++++++++++++ drivers/firmware/qcom/qcom_tee_uefisecapp.h | 120 +++++++ drivers/tee/qcomtee/call.c | 218 +++++++++++- drivers/tee/qcomtee/core.c | 9 +- drivers/tee/qcomtee/qcomtee.h | 18 + drivers/tee/qcomtee/qcomtee_msg.h | 1 + drivers/tee/qcomtee/qcomtee_object.h | 16 +- drivers/tee/tee_core.c | 26 +- include/linux/tee_core.h | 15 + include/linux/tee_drv.h | 18 +- 13 files changed, 968 insertions(+), 30 deletions(-) --- base-commit: f3e6330d7fe42b204af05a2dbc68b379e0ad179e change-id: 20260408-qcom_uefisecapp_migrate_qcomtee-13869d45e014 Best regards, -- Harshal Dev <harshal.dev(a)oss.qualcomm.com>

2 months, 1 week

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