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, 249 insertions, 0 deletions

diff --git a/net/mac80211/debug.h b/net/mac80211/debug.h
new file mode 100644
index 000000000..ef7c1a68d
--- /dev/null
+++ b/net/mac80211/debug.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Portions
+ * Copyright (C) 2022 - 2025 Intel Corporation
+ */
+#ifndef __MAC80211_DEBUG_H
+#define __MAC80211_DEBUG_H
+#include <linux/once_lite.h>
+#include <net/cfg80211.h>
+
+#ifdef CONFIG_MAC80211_OCB_DEBUG
+#define MAC80211_OCB_DEBUG 1
+#else
+#define MAC80211_OCB_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_IBSS_DEBUG
+#define MAC80211_IBSS_DEBUG 1
+#else
+#define MAC80211_IBSS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_PS_DEBUG
+#define MAC80211_PS_DEBUG 1
+#else
+#define MAC80211_PS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+#define MAC80211_HT_DEBUG 1
+#else
+#define MAC80211_HT_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MPL_DEBUG
+#define MAC80211_MPL_DEBUG 1
+#else
+#define MAC80211_MPL_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MPATH_DEBUG
+#define MAC80211_MPATH_DEBUG 1
+#else
+#define MAC80211_MPATH_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MHWMP_DEBUG
+#define MAC80211_MHWMP_DEBUG 1
+#else
+#define MAC80211_MHWMP_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_SYNC_DEBUG
+#define MAC80211_MESH_SYNC_DEBUG 1
+#else
+#define MAC80211_MESH_SYNC_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_CSA_DEBUG
+#define MAC80211_MESH_CSA_DEBUG 1
+#else
+#define MAC80211_MESH_CSA_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESH_PS_DEBUG
+#define MAC80211_MESH_PS_DEBUG 1
+#else
+#define MAC80211_MESH_PS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_TDLS_DEBUG
+#define MAC80211_TDLS_DEBUG 1
+#else
+#define MAC80211_TDLS_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_STA_DEBUG
+#define MAC80211_STA_DEBUG 1
+#else
+#define MAC80211_STA_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MLME_DEBUG
+#define MAC80211_MLME_DEBUG 1
+#else
+#define MAC80211_MLME_DEBUG 0
+#endif
+
+#ifdef CONFIG_MAC80211_MESSAGE_TRACING
+void __sdata_info(const char *fmt, ...) __printf(1, 2);
+void __sdata_dbg(bool print, const char *fmt, ...) __printf(2, 3);
+void __sdata_err(const char *fmt, ...) __printf(1, 2);
+void __wiphy_dbg(struct wiphy *wiphy, bool print, const char *fmt, ...)
+	__printf(3, 4);
+
+#define _sdata_info(sdata, fmt, ...)					\
+	__sdata_info("%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _sdata_dbg(print, sdata, fmt, ...)				\
+	__sdata_dbg(print, "%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _sdata_err(sdata, fmt, ...)					\
+	__sdata_err("%s: " fmt, (sdata)->name, ##__VA_ARGS__)
+#define _wiphy_dbg(print, wiphy, fmt, ...)				\
+	__wiphy_dbg(wiphy, print, fmt, ##__VA_ARGS__)
+#else
+#define _sdata_info(sdata, fmt, ...)					\
+do {									\
+	pr_info("%s: " fmt,						\
+		(sdata)->name, ##__VA_ARGS__);				\
+} while (0)
+
+#define _sdata_dbg(print, sdata, fmt, ...)				\
+do {									\
+	if (print)							\
+		pr_debug("%s: " fmt,					\
+			 (sdata)->name, ##__VA_ARGS__);			\
+} while (0)
+
+#define _sdata_err(sdata, fmt, ...)					\
+do {									\
+	pr_err("%s: " fmt,						\
+	       (sdata)->name, ##__VA_ARGS__);				\
+} while (0)
+
+#define _wiphy_dbg(print, wiphy, fmt, ...)				\
+do {									\
+	if (print)							\
+		wiphy_dbg((wiphy), fmt, ##__VA_ARGS__);			\
+} while (0)
+#endif
+
+#define sdata_info(sdata, fmt, ...)					\
+	_sdata_info(sdata, fmt, ##__VA_ARGS__)
+#define sdata_err(sdata, fmt, ...)					\
+	_sdata_err(sdata, fmt, ##__VA_ARGS__)
+#define sdata_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(1, sdata, fmt, ##__VA_ARGS__)
+
+#define link_info(link, fmt, ...)					\
+	do {								\
+		if (ieee80211_vif_is_mld(&(link)->sdata->vif))          \
+			_sdata_info((link)->sdata, "[link %d] " fmt,	\
+				    (link)->link_id,			\
+				    ##__VA_ARGS__);			\
+		else							\
+			_sdata_info((link)->sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_err(link, fmt, ...)					\
+	do {								\
+		if (ieee80211_vif_is_mld(&(link)->sdata->vif))          \
+			_sdata_err((link)->sdata, "[link %d] " fmt,	\
+				   (link)->link_id,			\
+				   ##__VA_ARGS__);			\
+		else							\
+			_sdata_err((link)->sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_err_once(link, fmt, ...)					\
+	DO_ONCE_LITE(link_err, link, fmt, ##__VA_ARGS__)
+#define link_id_info(sdata, link_id, fmt, ...)				\
+	do {								\
+		if (ieee80211_vif_is_mld(&sdata->vif))			\
+			_sdata_info(sdata, "[link %d] " fmt, link_id,	\
+				    ##__VA_ARGS__);			\
+		else							\
+			_sdata_info(sdata, fmt, ##__VA_ARGS__);		\
+	} while (0)
+#define _link_id_dbg(print, sdata, link_id, fmt, ...)			\
+	do {								\
+		if (ieee80211_vif_is_mld(&(sdata)->vif))		\
+			_sdata_dbg(print, sdata, "[link %d] " fmt,	\
+				   link_id, ##__VA_ARGS__);		\
+		else							\
+			_sdata_dbg(print, sdata, fmt, ##__VA_ARGS__);	\
+	} while (0)
+#define link_dbg(link, fmt, ...)					\
+	_link_id_dbg(1, (link)->sdata, (link)->link_id,			\
+		     fmt, ##__VA_ARGS__)
+
+#define ht_dbg(sdata, fmt, ...)						\
+	_sdata_dbg(MAC80211_HT_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ht_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_HT_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ocb_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_OCB_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ibss_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_IBSS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ps_dbg(sdata, fmt, ...)						\
+	_sdata_dbg(MAC80211_PS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define ps_dbg_hw(hw, fmt, ...)						\
+	_wiphy_dbg(MAC80211_PS_DEBUG,					\
+		   (hw)->wiphy, fmt, ##__VA_ARGS__)
+
+#define ps_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_PS_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mpl_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MPL_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mpath_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MPATH_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mhwmp_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MHWMP_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define msync_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_SYNC_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mcsa_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_CSA_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mps_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MESH_PS_DEBUG,				\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define tdls_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_TDLS_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define sta_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_STA_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#define mlme_dbg(sdata, fmt, ...)					\
+	_sdata_dbg(MAC80211_MLME_DEBUG,					\
+		   sdata, fmt, ##__VA_ARGS__)
+#define mlme_link_id_dbg(sdata, link_id, fmt, ...)			\
+	_link_id_dbg(MAC80211_MLME_DEBUG, sdata, link_id,		\
+		     fmt, ##__VA_ARGS__)
+
+#define mlme_dbg_ratelimited(sdata, fmt, ...)				\
+	_sdata_dbg(MAC80211_MLME_DEBUG && net_ratelimit(),		\
+		   sdata, fmt, ##__VA_ARGS__)
+
+#endif /* __MAC80211_DEBUG_H */