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, 166 insertions, 0 deletions

diff --git a/include/uapi/rdma/efa-abi.h b/include/uapi/rdma/efa-abi.h
new file mode 100644
index 000000000..d5c18f8de
--- /dev/null
+++ b/include/uapi/rdma/efa-abi.h
@@ -0,0 +1,166 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) */
+/*
+ * Copyright 2018-2026 Amazon.com, Inc. or its affiliates. All rights reserved.
+ */
+
+#ifndef EFA_ABI_USER_H
+#define EFA_ABI_USER_H
+
+#include <linux/types.h>
+#include <rdma/ib_user_ioctl_cmds.h>
+
+/*
+ * Increment this value if any changes that break userspace ABI
+ * compatibility are made.
+ */
+#define EFA_UVERBS_ABI_VERSION 1
+
+/*
+ * Keep structs aligned to 8 bytes.
+ * Keep reserved fields as arrays of __u8 named reserved_XXX where XXX is the
+ * hex bit offset of the field.
+ */
+
+enum {
+	EFA_ALLOC_UCONTEXT_CMD_SUPP_CAPS_TX_BATCH  = 1 << 0,
+	EFA_ALLOC_UCONTEXT_CMD_SUPP_CAPS_MIN_SQ_WR = 1 << 1,
+};
+
+struct efa_ibv_alloc_ucontext_cmd {
+	__u32 supported_caps;
+	__u8 reserved_20[4];
+};
+
+enum efa_ibv_user_cmds_supp_udata {
+	EFA_USER_CMDS_SUPP_UDATA_QUERY_DEVICE = 1 << 0,
+	EFA_USER_CMDS_SUPP_UDATA_CREATE_AH    = 1 << 1,
+};
+
+struct efa_ibv_alloc_ucontext_resp {
+	__u32 comp_mask;
+	__u32 cmds_supp_udata_mask;
+	__u16 sub_cqs_per_cq;
+	__u16 inline_buf_size;
+	__u32 max_llq_size; /* bytes */
+	__u16 max_tx_batch; /* units of 64 bytes */
+	__u16 min_sq_wr;
+	__u16 inline_buf_size_ex;
+	__u8 reserved_b0[2];
+};
+
+struct efa_ibv_alloc_pd_resp {
+	__u32 comp_mask;
+	__u16 pdn;
+	__u8 reserved_30[2];
+};
+
+enum {
+	EFA_CREATE_CQ_WITH_COMPLETION_CHANNEL = 1 << 0,
+	EFA_CREATE_CQ_WITH_SGID               = 1 << 1,
+};
+
+struct efa_ibv_create_cq {
+	__u32 comp_mask;
+	__u32 cq_entry_size;
+	__u16 num_sub_cqs;
+	__u8 flags;
+	__u8 reserved_58[5];
+};
+
+enum {
+	EFA_CREATE_CQ_RESP_DB_OFF = 1 << 0,
+};
+
+struct efa_ibv_create_cq_resp {
+	__u32 comp_mask;
+	__u8 reserved_20[4];
+	__aligned_u64 q_mmap_key;
+	__aligned_u64 q_mmap_size;
+	__u16 cq_idx;
+	__u8 reserved_d0[2];
+	__u32 db_off;
+	__aligned_u64 db_mmap_key;
+};
+
+enum {
+	EFA_QP_DRIVER_TYPE_SRD = 0,
+};
+
+enum {
+	EFA_CREATE_QP_WITH_UNSOLICITED_WRITE_RECV = 1 << 0,
+};
+
+struct efa_ibv_create_qp {
+	__u32 comp_mask;
+	__u32 rq_ring_size; /* bytes */
+	__u32 sq_ring_size; /* bytes */
+	__u32 driver_qp_type;
+	__u16 flags;
+	__u8 sl;
+	__u8 reserved_98[5];
+};
+
+struct efa_ibv_create_qp_resp {
+	__u32 comp_mask;
+	/* the offset inside the page of the rq db */
+	__u32 rq_db_offset;
+	/* the offset inside the page of the sq db */
+	__u32 sq_db_offset;
+	/* the offset inside the page of descriptors buffer */
+	__u32 llq_desc_offset;
+	__aligned_u64 rq_mmap_key;
+	__aligned_u64 rq_mmap_size;
+	__aligned_u64 rq_db_mmap_key;
+	__aligned_u64 sq_db_mmap_key;
+	__aligned_u64 llq_desc_mmap_key;
+	__u16 send_sub_cq_idx;
+	__u16 recv_sub_cq_idx;
+	__u8 reserved_1e0[4];
+};
+
+struct efa_ibv_create_ah_resp {
+	__u32 comp_mask;
+	__u16 efa_address_handle;
+	__u8 reserved_30[2];
+};
+
+enum {
+	EFA_QUERY_DEVICE_CAPS_RDMA_READ = 1 << 0,
+	EFA_QUERY_DEVICE_CAPS_RNR_RETRY = 1 << 1,
+	EFA_QUERY_DEVICE_CAPS_CQ_NOTIFICATIONS = 1 << 2,
+	EFA_QUERY_DEVICE_CAPS_CQ_WITH_SGID     = 1 << 3,
+	EFA_QUERY_DEVICE_CAPS_DATA_POLLING_128 = 1 << 4,
+	EFA_QUERY_DEVICE_CAPS_RDMA_WRITE = 1 << 5,
+	EFA_QUERY_DEVICE_CAPS_UNSOLICITED_WRITE_RECV = 1 << 6,
+	EFA_QUERY_DEVICE_CAPS_CQ_WITH_EXT_MEM = 1 << 7,
+};
+
+struct efa_ibv_ex_query_device_resp {
+	__u32 comp_mask;
+	__u32 max_sq_wr;
+	__u32 max_rq_wr;
+	__u16 max_sq_sge;
+	__u16 max_rq_sge;
+	__u32 max_rdma_size;
+	__u32 device_caps;
+};
+
+enum {
+	EFA_QUERY_MR_VALIDITY_RECV_IC_ID = 1 << 0,
+	EFA_QUERY_MR_VALIDITY_RDMA_READ_IC_ID = 1 << 1,
+	EFA_QUERY_MR_VALIDITY_RDMA_RECV_IC_ID = 1 << 2,
+};
+
+enum efa_query_mr_attrs {
+	EFA_IB_ATTR_QUERY_MR_HANDLE = (1U << UVERBS_ID_NS_SHIFT),
+	EFA_IB_ATTR_QUERY_MR_RESP_IC_ID_VALIDITY,
+	EFA_IB_ATTR_QUERY_MR_RESP_RECV_IC_ID,
+	EFA_IB_ATTR_QUERY_MR_RESP_RDMA_READ_IC_ID,
+	EFA_IB_ATTR_QUERY_MR_RESP_RDMA_RECV_IC_ID,
+};
+
+enum efa_mr_methods {
+	EFA_IB_METHOD_MR_QUERY = (1U << UVERBS_ID_NS_SHIFT),
+};
+
+#endif /* EFA_ABI_USER_H */