From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- Documentation/driver-api/tee.rst | 54 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 Documentation/driver-api/tee.rst (limited to 'Documentation/driver-api/tee.rst') diff --git a/Documentation/driver-api/tee.rst b/Documentation/driver-api/tee.rst new file mode 100644 index 000000000..4d58ac071 --- /dev/null +++ b/Documentation/driver-api/tee.rst @@ -0,0 +1,54 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +TEE (Trusted Execution Environment) driver API +=============================================== + +Kernel provides a TEE bus infrastructure where a Trusted Application is +represented as a device identified via Universally Unique Identifier (UUID) and +client drivers register a table of supported device UUIDs. + +TEE bus infrastructure registers following APIs: + +match(): + iterates over the client driver UUID table to find a corresponding + match for device UUID. If a match is found, then this particular device is + probed via corresponding probe API registered by the client driver. This + process happens whenever a device or a client driver is registered with TEE + bus. + +uevent(): + notifies user-space (udev) whenever a new device is registered on + TEE bus for auto-loading of modularized client drivers. + +TEE bus device enumeration is specific to underlying TEE implementation, so it +is left open for TEE drivers to provide corresponding implementation. + +Then TEE client driver can talk to a matched Trusted Application using APIs +listed in include/linux/tee_drv.h. + +TEE client driver example +------------------------- + +Suppose a TEE client driver needs to communicate with a Trusted Application +having UUID: ``ac6a4085-0e82-4c33-bf98-8eb8e118b6c2``, so driver registration +snippet would look like:: + + static const struct tee_client_device_id client_id_table[] = { + {UUID_INIT(0xac6a4085, 0x0e82, 0x4c33, + 0xbf, 0x98, 0x8e, 0xb8, 0xe1, 0x18, 0xb6, 0xc2)}, + {} + }; + + MODULE_DEVICE_TABLE(tee, client_id_table); + + static struct tee_client_driver client_driver = { + .probe = client_probe, + .remove = client_remove, + .id_table = client_id_table, + .driver = { + .name = DRIVER_NAME, + }, + }; + + module_tee_client_driver(client_driver); -- cgit v1.3.1