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, 115 insertions, 0 deletions

diff --git a/include/uapi/rdma/ionic-abi.h b/include/uapi/rdma/ionic-abi.h
new file mode 100644
index 000000000..7b589d3e9
--- /dev/null
+++ b/include/uapi/rdma/ionic-abi.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc */
+
+#ifndef IONIC_ABI_H
+#define IONIC_ABI_H
+
+#include <linux/types.h>
+
+#define IONIC_ABI_VERSION	1
+
+#define IONIC_EXPDB_64		1
+#define IONIC_EXPDB_128		2
+#define IONIC_EXPDB_256		4
+#define IONIC_EXPDB_512		8
+
+#define IONIC_EXPDB_SQ		1
+#define IONIC_EXPDB_RQ		2
+
+#define IONIC_CMB_ENABLE	1
+#define IONIC_CMB_REQUIRE	2
+#define IONIC_CMB_EXPDB		4
+#define IONIC_CMB_WC		8
+#define IONIC_CMB_UC		16
+
+struct ionic_ctx_req {
+	__u32 rsvd[2];
+};
+
+struct ionic_ctx_resp {
+	__u32 rsvd;
+	__u32 page_shift;
+
+	__aligned_u64 dbell_offset;
+
+	__u16 version;
+	__u8 qp_opcodes;
+	__u8 admin_opcodes;
+
+	__u8 sq_qtype;
+	__u8 rq_qtype;
+	__u8 cq_qtype;
+	__u8 admin_qtype;
+
+	__u8 max_stride;
+	__u8 max_spec;
+	__u8 udma_count;
+	__u8 expdb_mask;
+	__u8 expdb_qtypes;
+
+	__u8 rsvd2[3];
+};
+
+struct ionic_qdesc {
+	__aligned_u64 addr;
+	__u32 size;
+	__u16 mask;
+	__u8 depth_log2;
+	__u8 stride_log2;
+};
+
+struct ionic_ah_resp {
+	__u32 ahid;
+	__u32 pad;
+};
+
+struct ionic_cq_req {
+	struct ionic_qdesc cq[2];
+	__u8 udma_mask;
+	__u8 rsvd[7];
+};
+
+struct ionic_cq_resp {
+	__u32 cqid[2];
+	__u8 udma_mask;
+	__u8 rsvd[7];
+};
+
+struct ionic_qp_req {
+	struct ionic_qdesc sq;
+	struct ionic_qdesc rq;
+	__u8 sq_spec;
+	__u8 rq_spec;
+	__u8 sq_cmb;
+	__u8 rq_cmb;
+	__u8 udma_mask;
+	__u8 rsvd[3];
+};
+
+struct ionic_qp_resp {
+	__u32 qpid;
+	__u8 sq_cmb;
+	__u8 rq_cmb;
+	__u8 udma_idx;
+	__u8 rsvd[1];
+	__aligned_u64 sq_cmb_offset;
+	__aligned_u64 rq_cmb_offset;
+};
+
+struct ionic_srq_req {
+	struct ionic_qdesc rq;
+	__u8 rq_spec;
+	__u8 rq_cmb;
+	__u8 udma_mask;
+	__u8 rsvd[5];
+};
+
+struct ionic_srq_resp {
+	__u32 qpid;
+	__u8 rq_cmb;
+	__u8 udma_idx;
+	__u8 rsvd[2];
+	__aligned_u64 rq_cmb_offset;
+};
+
+#endif /* IONIC_ABI_H */