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, 109 insertions, 0 deletions

diff --git a/Documentation/driver-api/infiniband.rst b/Documentation/driver-api/infiniband.rst
new file mode 100644
index 000000000..d48f24677
--- /dev/null
+++ b/Documentation/driver-api/infiniband.rst
@@ -0,0 +1,109 @@
+===========================================
+InfiniBand and Remote DMA (RDMA) Interfaces
+===========================================
+
+Introduction and Overview
+=========================
+
+TBD
+
+InfiniBand core interfaces
+==========================
+
+.. kernel-doc:: drivers/infiniband/core/iwpm_util.h
+    :internal:
+
+.. kernel-doc:: drivers/infiniband/core/cq.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/cm.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/rw.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/device.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/verbs.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/packer.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/sa_query.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/ud_header.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/umem.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/core/umem_odp.c
+    :export:
+
+RDMA Verbs transport library
+============================
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/mr.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/rc.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/ah.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/vt.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/cq.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/qp.c
+    :export:
+
+.. kernel-doc:: drivers/infiniband/sw/rdmavt/mcast.c
+    :export:
+
+Upper Layer Protocols
+=====================
+
+iSCSI Extensions for RDMA (iSER)
+--------------------------------
+
+.. kernel-doc:: drivers/infiniband/ulp/iser/iscsi_iser.h
+   :internal:
+
+.. kernel-doc:: drivers/infiniband/ulp/iser/iscsi_iser.c
+   :functions: iscsi_iser_pdu_alloc iser_initialize_task_headers
+               iscsi_iser_task_init iscsi_iser_mtask_xmit iscsi_iser_task_xmit
+               iscsi_iser_cleanup_task iscsi_iser_check_protection
+               iscsi_iser_conn_create iscsi_iser_conn_bind
+               iscsi_iser_conn_start iscsi_iser_conn_stop
+               iscsi_iser_session_destroy iscsi_iser_session_create
+               iscsi_iser_set_param iscsi_iser_ep_connect iscsi_iser_ep_poll
+               iscsi_iser_ep_disconnect
+
+.. kernel-doc:: drivers/infiniband/ulp/iser/iser_initiator.c
+   :internal:
+
+.. kernel-doc:: drivers/infiniband/ulp/iser/iser_verbs.c
+   :internal:
+
+InfiniBand SCSI RDMA protocol target support
+--------------------------------------------
+
+.. kernel-doc:: drivers/infiniband/ulp/srpt/ib_srpt.h
+   :internal:
+
+.. kernel-doc:: drivers/infiniband/ulp/srpt/ib_srpt.c
+   :internal:
+
+iSCSI Extensions for RDMA (iSER) target support
+-----------------------------------------------
+
+.. kernel-doc:: drivers/infiniband/ulp/isert/ib_isert.c
+   :internal:
+