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, 93 insertions, 0 deletions

diff --git a/drivers/scsi/fcoe/fcoe.h b/drivers/scsi/fcoe/fcoe.h
new file mode 100644
index 000000000..520c53512
--- /dev/null
+++ b/drivers/scsi/fcoe/fcoe.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright(c) 2009 Intel Corporation. All rights reserved.
+ *
+ * Maintained at www.Open-FCoE.org
+ */
+
+#ifndef _FCOE_H_
+#define _FCOE_H_
+
+#include <linux/skbuff.h>
+#include <linux/kthread.h>
+
+#define FCOE_MAX_QUEUE_DEPTH	256
+#define FCOE_MIN_QUEUE_DEPTH	32
+
+#define FCOE_WORD_TO_BYTE	4
+
+#define FCOE_VERSION	"0.1"
+#define FCOE_NAME	"fcoe"
+#define FCOE_VENDOR	"Open-FCoE.org"
+
+#define FCOE_MAX_LUN		0xFFFF
+#define FCOE_MAX_FCP_TARGET	256
+
+#define FCOE_MAX_OUTSTANDING_COMMANDS	1024
+
+#define FCOE_MIN_XID		0x0000	/* the min xid supported by fcoe_sw */
+#define FCOE_MAX_XID		0x0FFF	/* the max xid supported by fcoe_sw */
+
+extern unsigned int fcoe_debug_logging;
+
+#define FCOE_LOGGING	    0x01 /* General logging, not categorized */
+#define FCOE_NETDEV_LOGGING 0x02 /* Netdevice logging */
+
+#define FCOE_CHECK_LOGGING(LEVEL, CMD)					\
+do {                                                            	\
+	if (unlikely(fcoe_debug_logging & LEVEL))			\
+		do {							\
+			CMD;						\
+		} while (0);						\
+} while (0)
+
+#define FCOE_DBG(fmt, args...)						\
+	FCOE_CHECK_LOGGING(FCOE_LOGGING,				\
+			   pr_info("fcoe: " fmt, ##args);)
+
+#define FCOE_NETDEV_DBG(netdev, fmt, args...)			\
+	FCOE_CHECK_LOGGING(FCOE_NETDEV_LOGGING,			\
+			   pr_info("fcoe: %s: " fmt,		\
+				   netdev->name, ##args);)
+
+/**
+ * struct fcoe_interface - A FCoE interface
+ * @list:	      Handle for a list of FCoE interfaces
+ * @netdev:	      The associated net device
+ * @fcoe_packet_type: FCoE packet type
+ * @fip_packet_type:  FIP packet type
+ * @oem:	      The offload exchange manager for all local port
+ *		      instances associated with this port
+ * @removed:	      Indicates fcoe interface removed from net device
+ * @priority:	      Priority for the FCoE packet (DCB)
+ * This structure is 1:1 with a net device.
+ */
+struct fcoe_interface {
+	struct list_head   list;
+	struct net_device  *netdev;
+	struct net_device  *realdev;
+	struct packet_type fcoe_packet_type;
+	struct packet_type fip_packet_type;
+	struct packet_type fip_vlan_packet_type;
+	struct fc_exch_mgr *oem;
+	u8	removed;
+	u8	priority;
+};
+
+#define fcoe_to_ctlr(x)						\
+	(struct fcoe_ctlr *)(((struct fcoe_ctlr *)(x)) - 1)
+
+#define fcoe_from_ctlr(x)			\
+	((struct fcoe_interface *)((x) + 1))
+
+/**
+ * fcoe_netdev() - Return the net device associated with a local port
+ * @lport: The local port to get the net device from
+ */
+static inline struct net_device *fcoe_netdev(const struct fc_lport *lport)
+{
+	return ((struct fcoe_interface *)
+			((struct fcoe_port *)lport_priv(lport))->priv)->netdev;
+}
+
+#endif /* _FCOE_H_ */