kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

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 <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 116 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/tee-dev.h b/drivers/crypto/ccp/tee-dev.h
new file mode 100644
index 000000000..c23416cb7
--- /dev/null
+++ b/drivers/crypto/ccp/tee-dev.h
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright (C) 2019,2021 Advanced Micro Devices, Inc.
+ *
+ * Author: Rijo Thomas <Rijo-john.Thomas@amd.com>
+ * Author: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
+ *
+ */
+
+/* This file describes the TEE communication interface between host and AMD
+ * Secure Processor
+ */
+
+#ifndef __TEE_DEV_H__
+#define __TEE_DEV_H__
+
+#include <linux/device.h>
+#include <linux/mutex.h>
+
+#define TEE_DEFAULT_CMD_TIMEOUT		(10 * MSEC_PER_SEC)
+#define TEE_DEFAULT_RING_TIMEOUT	10
+#define MAX_BUFFER_SIZE			988
+
+/**
+ * struct tee_init_ring_cmd - Command to init TEE ring buffer
+ * @low_addr:  bits [31:0] of the physical address of ring buffer
+ * @hi_addr:   bits [63:32] of the physical address of ring buffer
+ * @size:      size of ring buffer in bytes
+ */
+struct tee_init_ring_cmd {
+	u32 low_addr;
+	u32 hi_addr;
+	u32 size;
+};
+
+#define MAX_RING_BUFFER_ENTRIES		32
+
+/**
+ * struct ring_buf_manager - Helper structure to manage ring buffer.
+ * @ring_start:  starting address of ring buffer
+ * @ring_size:   size of ring buffer in bytes
+ * @ring_pa:     physical address of ring buffer
+ * @wptr:        index to the last written entry in ring buffer
+ */
+struct ring_buf_manager {
+	struct mutex mutex;	/* synchronizes access to ring buffer */
+	void *ring_start;
+	u32 ring_size;
+	phys_addr_t ring_pa;
+	u32 wptr;
+};
+
+struct psp_tee_device {
+	struct device *dev;
+	struct psp_device *psp;
+	void __iomem *io_regs;
+	struct tee_vdata *vdata;
+	struct ring_buf_manager rb_mgr;
+};
+
+/**
+ * enum tee_cmd_state - TEE command states for the ring buffer interface
+ * @TEE_CMD_STATE_INIT:      initial state of command when sent from host
+ * @TEE_CMD_STATE_PROCESS:   command being processed by TEE environment
+ * @TEE_CMD_STATE_COMPLETED: command processing completed
+ */
+enum tee_cmd_state {
+	TEE_CMD_STATE_INIT,
+	TEE_CMD_STATE_PROCESS,
+	TEE_CMD_STATE_COMPLETED,
+};
+
+/**
+ * enum cmd_resp_state - TEE command's response status maintained by driver
+ * @CMD_RESPONSE_INVALID:      initial state when no command is written to ring
+ * @CMD_WAITING_FOR_RESPONSE:  driver waiting for response from TEE
+ * @CMD_RESPONSE_TIMEDOUT:     failed to get response from TEE
+ * @CMD_RESPONSE_COPIED:       driver has copied response from TEE
+ */
+enum cmd_resp_state {
+	CMD_RESPONSE_INVALID,
+	CMD_WAITING_FOR_RESPONSE,
+	CMD_RESPONSE_TIMEDOUT,
+	CMD_RESPONSE_COPIED,
+};
+
+/**
+ * struct tee_ring_cmd - Structure of the command buffer in TEE ring
+ * @cmd_id:      refers to &enum tee_cmd_id. Command id for the ring buffer
+ *               interface
+ * @cmd_state:   refers to &enum tee_cmd_state
+ * @status:      status of TEE command execution
+ * @res0:        reserved region
+ * @pdata:       private data (currently unused)
+ * @res1:        reserved region
+ * @buf:         TEE command specific buffer
+ * @flag:	 refers to &enum cmd_resp_state
+ */
+struct tee_ring_cmd {
+	u32 cmd_id;
+	u32 cmd_state;
+	u32 status;
+	u32 res0[1];
+	u64 pdata;
+	u32 res1[2];
+	u8 buf[MAX_BUFFER_SIZE];
+	u32 flag;
+
+	/* Total size: 1024 bytes */
+} __packed;
+
+int tee_dev_init(struct psp_device *psp);
+void tee_dev_destroy(struct psp_device *psp);
+int tee_restore(struct psp_device *psp);
+
+#endif /* __TEE_DEV_H__ */