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 --- include/cxl/mailbox.h | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 include/cxl/mailbox.h (limited to 'include/cxl/mailbox.h') diff --git a/include/cxl/mailbox.h b/include/cxl/mailbox.h new file mode 100644 index 000000000..c4e99e2e3 --- /dev/null +++ b/include/cxl/mailbox.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* Copyright(c) 2024 Intel Corporation. */ +#ifndef __CXL_MBOX_H__ +#define __CXL_MBOX_H__ +#include +#include +#include + +/** + * struct cxl_mbox_cmd - A command to be submitted to hardware. + * @opcode: (input) The command set and command submitted to hardware. + * @payload_in: (input) Pointer to the input payload. + * @payload_out: (output) Pointer to the output payload. Must be allocated by + * the caller. + * @size_in: (input) Number of bytes to load from @payload_in. + * @size_out: (input) Max number of bytes loaded into @payload_out. + * (output) Number of bytes generated by the device. For fixed size + * outputs commands this is always expected to be deterministic. For + * variable sized output commands, it tells the exact number of bytes + * written. + * @min_out: (input) internal command output payload size validation + * @poll_count: (input) Number of timeouts to attempt. + * @poll_interval_ms: (input) Time between mailbox background command polling + * interval timeouts. + * @return_code: (output) Error code returned from hardware. + * + * This is the primary mechanism used to send commands to the hardware. + * All the fields except @payload_* correspond exactly to the fields described in + * Command Register section of the CXL 2.0 8.2.8.4.5. @payload_in and + * @payload_out are written to, and read from the Command Payload Registers + * defined in CXL 2.0 8.2.8.4.8. + */ +struct cxl_mbox_cmd { + u16 opcode; + void *payload_in; + void *payload_out; + size_t size_in; + size_t size_out; + size_t min_out; + int poll_count; + int poll_interval_ms; + u16 return_code; +}; + +/** + * struct cxl_mailbox - context for CXL mailbox operations + * @host: device that hosts the mailbox + * @enabled_cmds: mailbox commands that are enabled by the driver + * @exclusive_cmds: mailbox commands that are exclusive to the kernel + * @payload_size: Size of space for payload + * (CXL 3.1 8.2.8.4.3 Mailbox Capabilities Register) + * @mbox_mutex: mutex protects device mailbox and firmware + * @mbox_wait: rcuwait for mailbox + * @mbox_send: @dev specific transport for transmitting mailbox commands + * @feat_cap: Features capability + */ +struct cxl_mailbox { + struct device *host; + DECLARE_BITMAP(enabled_cmds, CXL_MEM_COMMAND_ID_MAX); + DECLARE_BITMAP(exclusive_cmds, CXL_MEM_COMMAND_ID_MAX); + size_t payload_size; + struct mutex mbox_mutex; /* lock to protect mailbox context */ + struct rcuwait mbox_wait; + int (*mbox_send)(struct cxl_mailbox *cxl_mbox, struct cxl_mbox_cmd *cmd); + enum cxl_features_capability feat_cap; +}; + +int cxl_mailbox_init(struct cxl_mailbox *cxl_mbox, struct device *host); + +#endif -- cgit v1.3.1