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, 34 insertions, 0 deletions

diff --git a/include/soc/qcom/ice.h b/include/soc/qcom/ice.h
new file mode 100644
index 000000000..4bee553f0
--- /dev/null
+++ b/include/soc/qcom/ice.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023, Linaro Limited
+ */
+
+#ifndef __QCOM_ICE_H__
+#define __QCOM_ICE_H__
+
+#include <linux/blk-crypto.h>
+#include <linux/types.h>
+
+struct qcom_ice;
+
+int qcom_ice_enable(struct qcom_ice *ice);
+int qcom_ice_resume(struct qcom_ice *ice);
+int qcom_ice_suspend(struct qcom_ice *ice);
+int qcom_ice_program_key(struct qcom_ice *ice, unsigned int slot,
+			 const struct blk_crypto_key *blk_key);
+int qcom_ice_evict_key(struct qcom_ice *ice, int slot);
+enum blk_crypto_key_type qcom_ice_get_supported_key_type(struct qcom_ice *ice);
+int qcom_ice_derive_sw_secret(struct qcom_ice *ice,
+			      const u8 *eph_key, size_t eph_key_size,
+			      u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]);
+int qcom_ice_generate_key(struct qcom_ice *ice,
+			  u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+int qcom_ice_prepare_key(struct qcom_ice *ice,
+			 const u8 *lt_key, size_t lt_key_size,
+			 u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+int qcom_ice_import_key(struct qcom_ice *ice,
+			const u8 *raw_key, size_t raw_key_size,
+			u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
+struct qcom_ice *devm_of_qcom_ice_get(struct device *dev);
+
+#endif /* __QCOM_ICE_H__ */