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, 132 insertions, 0 deletions

diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
new file mode 100644
index 000000000..bdb065d14
--- /dev/null
+++ b/net/wireless/nl80211.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Portions of this file
+ * Copyright (C) 2018, 2020-2026 Intel Corporation
+ */
+#ifndef __NET_WIRELESS_NL80211_H
+#define __NET_WIRELESS_NL80211_H
+
+#include "core.h"
+
+int nl80211_init(void);
+void nl80211_exit(void);
+
+void *nl80211hdr_put(struct sk_buff *skb, u32 portid, u32 seq,
+		     int flags, u8 cmd);
+bool nl80211_put_sta_rate(struct sk_buff *msg, struct rate_info *info,
+			  int attr);
+
+static inline u64 wdev_id(struct wireless_dev *wdev)
+{
+	return (u64)wdev->identifier |
+	       ((u64)wiphy_to_rdev(wdev->wiphy)->wiphy_idx << 32);
+}
+
+int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
+			  struct netlink_ext_ack *extack,
+			  struct nlattr **attrs,
+			  struct cfg80211_chan_def *chandef,
+			  bool npca_permitted);
+int nl80211_parse_random_mac(struct nlattr **attrs,
+			     u8 *mac_addr, u8 *mac_addr_mask);
+
+void nl80211_notify_wiphy(struct cfg80211_registered_device *rdev,
+			  enum nl80211_commands cmd);
+void nl80211_notify_iface(struct cfg80211_registered_device *rdev,
+			  struct wireless_dev *wdev,
+			  enum nl80211_commands cmd);
+void nl80211_send_scan_start(struct cfg80211_registered_device *rdev,
+			     struct wireless_dev *wdev);
+struct sk_buff *nl80211_build_scan_msg(struct cfg80211_registered_device *rdev,
+				       struct wireless_dev *wdev, bool aborted);
+void nl80211_send_scan_msg(struct cfg80211_registered_device *rdev,
+			   struct sk_buff *msg);
+void nl80211_send_sched_scan(struct cfg80211_sched_scan_request *req, u32 cmd);
+void nl80211_common_reg_change_event(enum nl80211_commands cmd_id,
+				     struct regulatory_request *request);
+
+static inline void
+nl80211_send_reg_change_event(struct regulatory_request *request)
+{
+	nl80211_common_reg_change_event(NL80211_CMD_REG_CHANGE, request);
+}
+
+static inline void
+nl80211_send_wiphy_reg_change_event(struct regulatory_request *request)
+{
+	nl80211_common_reg_change_event(NL80211_CMD_WIPHY_REG_CHANGE, request);
+}
+
+void nl80211_send_rx_auth(struct cfg80211_registered_device *rdev,
+			  struct net_device *netdev,
+			  const u8 *buf, size_t len, gfp_t gfp);
+void nl80211_send_rx_assoc(struct cfg80211_registered_device *rdev,
+			   struct net_device *netdev,
+			   const struct cfg80211_rx_assoc_resp_data *data);
+void nl80211_send_deauth(struct cfg80211_registered_device *rdev,
+			 struct net_device *netdev,
+			 const u8 *buf, size_t len,
+			 bool reconnect, gfp_t gfp);
+void nl80211_send_disassoc(struct cfg80211_registered_device *rdev,
+			   struct net_device *netdev,
+			   const u8 *buf, size_t len,
+			   bool reconnect, gfp_t gfp);
+void nl80211_send_auth_timeout(struct cfg80211_registered_device *rdev,
+			       struct net_device *netdev,
+			       const u8 *addr, gfp_t gfp);
+void nl80211_send_assoc_timeout(struct cfg80211_registered_device *rdev,
+				struct net_device *netdev,
+				const u8 *addr, gfp_t gfp);
+void nl80211_send_connect_result(struct cfg80211_registered_device *rdev,
+				 struct net_device *netdev,
+				 struct cfg80211_connect_resp_params *params,
+				 gfp_t gfp);
+void nl80211_send_roamed(struct cfg80211_registered_device *rdev,
+			 struct net_device *netdev,
+			 struct cfg80211_roam_info *info, gfp_t gfp);
+/* For STA/GC, indicate port authorized with AP/GO bssid.
+ * For GO/AP, use peer GC/STA mac_addr.
+ */
+void nl80211_send_port_authorized(struct cfg80211_registered_device *rdev,
+				  struct net_device *netdev, const u8 *peer_addr,
+				  const u8 *td_bitmap, u8 td_bitmap_len);
+void nl80211_send_disconnected(struct cfg80211_registered_device *rdev,
+			       struct net_device *netdev, u16 reason,
+			       const u8 *ie, size_t ie_len, bool from_ap);
+
+void
+nl80211_michael_mic_failure(struct cfg80211_registered_device *rdev,
+			    struct net_device *netdev, const u8 *addr,
+			    enum nl80211_key_type key_type,
+			    int key_id, const u8 *tsc, gfp_t gfp);
+
+void
+nl80211_send_beacon_hint_event(struct wiphy *wiphy,
+			       struct ieee80211_channel *channel_before,
+			       struct ieee80211_channel *channel_after);
+
+void nl80211_send_ibss_bssid(struct cfg80211_registered_device *rdev,
+			     struct net_device *netdev, const u8 *bssid,
+			     gfp_t gfp);
+
+int nl80211_send_mgmt(struct cfg80211_registered_device *rdev,
+		      struct wireless_dev *wdev, u32 nlpid,
+		      struct cfg80211_rx_info *info, gfp_t gfp);
+
+void
+nl80211_radar_notify(struct cfg80211_registered_device *rdev,
+		     const struct cfg80211_chan_def *chandef,
+		     enum nl80211_radar_event event,
+		     struct net_device *netdev, gfp_t gfp);
+
+void nl80211_send_ap_stopped(struct wireless_dev *wdev, unsigned int link_id);
+
+void cfg80211_free_coalesce(struct cfg80211_coalesce *coalesce);
+
+/* peer measurement */
+int nl80211_pmsr_start(struct sk_buff *skb, struct genl_info *info);
+
+void nl80211_mlo_reconf_add_done(struct net_device *dev,
+				 struct cfg80211_mlo_reconf_done_data *data);
+
+#endif /* __NET_WIRELESS_NL80211_H */