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, 496 insertions, 0 deletions

diff --git a/net/wireless/ibss.c b/net/wireless/ibss.c
new file mode 100644
index 000000000..b1d748bdb
--- /dev/null
+++ b/net/wireless/ibss.c
@@ -0,0 +1,496 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Some IBSS support code for cfg80211.
+ *
+ * Copyright 2009	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright (C) 2020-2026 Intel Corporation
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <net/cfg80211.h>
+#include "wext-compat.h"
+#include "nl80211.h"
+#include "rdev-ops.h"
+
+
+void __cfg80211_ibss_joined(struct net_device *dev, const u8 *bssid,
+			    struct ieee80211_channel *channel)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_bss *bss;
+#ifdef CONFIG_CFG80211_WEXT
+	union iwreq_data wrqu;
+#endif
+
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return;
+
+	if (!wdev->u.ibss.ssid_len)
+		return;
+
+	bss = cfg80211_get_bss(wdev->wiphy, channel, bssid, NULL, 0,
+			       IEEE80211_BSS_TYPE_IBSS, IEEE80211_PRIVACY_ANY);
+
+	if (WARN_ON(!bss))
+		return;
+
+	if (wdev->u.ibss.current_bss) {
+		cfg80211_unhold_bss(wdev->u.ibss.current_bss);
+		cfg80211_put_bss(wdev->wiphy, &wdev->u.ibss.current_bss->pub);
+	}
+
+	cfg80211_hold_bss(bss_from_pub(bss));
+	wdev->u.ibss.current_bss = bss_from_pub(bss);
+
+	cfg80211_upload_connect_keys(wdev);
+
+	nl80211_send_ibss_bssid(wiphy_to_rdev(wdev->wiphy), dev, bssid,
+				GFP_KERNEL);
+#ifdef CONFIG_CFG80211_WEXT
+	memset(&wrqu, 0, sizeof(wrqu));
+	memcpy(wrqu.ap_addr.sa_data, bssid, ETH_ALEN);
+	wireless_send_event(dev, SIOCGIWAP, &wrqu, NULL);
+#endif
+}
+
+void cfg80211_ibss_joined(struct net_device *dev, const u8 *bssid,
+			  struct ieee80211_channel *channel, gfp_t gfp)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	struct cfg80211_event *ev;
+	unsigned long flags;
+
+	trace_cfg80211_ibss_joined(dev, bssid, channel);
+
+	if (WARN_ON(!channel))
+		return;
+
+	ev = kzalloc_obj(*ev, gfp);
+	if (!ev)
+		return;
+
+	ev->type = EVENT_IBSS_JOINED;
+	memcpy(ev->ij.bssid, bssid, ETH_ALEN);
+	ev->ij.channel = channel;
+
+	spin_lock_irqsave(&wdev->event_lock, flags);
+	list_add_tail(&ev->list, &wdev->event_list);
+	spin_unlock_irqrestore(&wdev->event_lock, flags);
+	queue_work(cfg80211_wq, &rdev->event_work);
+}
+EXPORT_SYMBOL(cfg80211_ibss_joined);
+
+int __cfg80211_join_ibss(struct cfg80211_registered_device *rdev,
+			 struct net_device *dev,
+			 struct cfg80211_ibss_params *params,
+			 struct cfg80211_cached_keys *connkeys)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	int err;
+
+	lockdep_assert_held(&rdev->wiphy.mtx);
+
+	if (wdev->links[0].cac_started)
+		return -EBUSY;
+
+	if (wdev->u.ibss.ssid_len)
+		return -EALREADY;
+
+	if (!params->basic_rates) {
+		/*
+		* If no rates were explicitly configured,
+		* use the mandatory rate set for 11b or
+		* 11a for maximum compatibility.
+		*/
+		struct ieee80211_supported_band *sband;
+		enum nl80211_band band;
+		u32 flag;
+		int j;
+
+		band = params->chandef.chan->band;
+		if (band == NL80211_BAND_5GHZ ||
+		    band == NL80211_BAND_6GHZ)
+			flag = IEEE80211_RATE_MANDATORY_A;
+		else
+			flag = IEEE80211_RATE_MANDATORY_B;
+
+		sband = rdev->wiphy.bands[band];
+		for (j = 0; j < sband->n_bitrates; j++) {
+			if (sband->bitrates[j].flags & flag)
+				params->basic_rates |= BIT(j);
+		}
+	}
+
+	if (WARN_ON(connkeys && connkeys->def < 0))
+		return -EINVAL;
+
+	if (WARN_ON(wdev->connect_keys))
+		kfree_sensitive(wdev->connect_keys);
+	wdev->connect_keys = connkeys;
+
+	wdev->u.ibss.chandef = params->chandef;
+	if (connkeys) {
+		params->wep_keys = connkeys->params;
+		params->wep_tx_key = connkeys->def;
+	}
+
+#ifdef CONFIG_CFG80211_WEXT
+	wdev->wext.ibss.chandef = params->chandef;
+#endif
+	err = rdev_join_ibss(rdev, dev, params);
+	if (err) {
+		wdev->connect_keys = NULL;
+		return err;
+	}
+
+	memcpy(wdev->u.ibss.ssid, params->ssid, params->ssid_len);
+	wdev->u.ibss.ssid_len = params->ssid_len;
+
+	return 0;
+}
+
+void cfg80211_clear_ibss(struct net_device *dev, bool nowext)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	int i;
+
+	lockdep_assert_wiphy(wdev->wiphy);
+
+	kfree_sensitive(wdev->connect_keys);
+	wdev->connect_keys = NULL;
+
+	rdev_set_qos_map(rdev, dev, NULL);
+
+	/*
+	 * Delete all the keys ... pairwise keys can't really
+	 * exist any more anyway, but default keys might.
+	 */
+	if (rdev->ops->del_key)
+		for (i = 0; i < 6; i++)
+			rdev_del_key(rdev, wdev, -1, i, false, NULL);
+
+	if (wdev->u.ibss.current_bss) {
+		cfg80211_unhold_bss(wdev->u.ibss.current_bss);
+		cfg80211_put_bss(wdev->wiphy, &wdev->u.ibss.current_bss->pub);
+	}
+
+	wdev->u.ibss.current_bss = NULL;
+	wdev->u.ibss.ssid_len = 0;
+	memset(&wdev->u.ibss.chandef, 0, sizeof(wdev->u.ibss.chandef));
+#ifdef CONFIG_CFG80211_WEXT
+	if (!nowext)
+		wdev->wext.ibss.ssid_len = 0;
+#endif
+	cfg80211_sched_dfs_chan_update(rdev);
+}
+
+int cfg80211_leave_ibss(struct cfg80211_registered_device *rdev,
+			struct net_device *dev, bool nowext)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	int err;
+
+	lockdep_assert_wiphy(wdev->wiphy);
+
+	if (!wdev->u.ibss.ssid_len)
+		return -ENOLINK;
+
+	err = rdev_leave_ibss(rdev, dev);
+
+	if (err)
+		return err;
+
+	wdev->conn_owner_nlportid = 0;
+	cfg80211_clear_ibss(dev, nowext);
+
+	return 0;
+}
+
+#ifdef CONFIG_CFG80211_WEXT
+int cfg80211_ibss_wext_join(struct cfg80211_registered_device *rdev,
+			    struct wireless_dev *wdev)
+{
+	struct cfg80211_cached_keys *ck = NULL;
+	enum nl80211_band band;
+	int i, err;
+
+	lockdep_assert_wiphy(wdev->wiphy);
+
+	if (!wdev->wext.ibss.beacon_interval)
+		wdev->wext.ibss.beacon_interval = 100;
+
+	/* try to find an IBSS channel if none requested ... */
+	if (!wdev->wext.ibss.chandef.chan) {
+		struct ieee80211_channel *new_chan = NULL;
+
+		for (band = 0; band < NUM_NL80211_BANDS; band++) {
+			struct ieee80211_supported_band *sband;
+			struct ieee80211_channel *chan;
+
+			sband = rdev->wiphy.bands[band];
+			if (!sband)
+				continue;
+
+			for (i = 0; i < sband->n_channels; i++) {
+				chan = &sband->channels[i];
+				if (chan->flags & IEEE80211_CHAN_NO_IR)
+					continue;
+				if (chan->flags & IEEE80211_CHAN_DISABLED)
+					continue;
+				new_chan = chan;
+				break;
+			}
+
+			if (new_chan)
+				break;
+		}
+
+		if (!new_chan)
+			return -EINVAL;
+
+		cfg80211_chandef_create(&wdev->wext.ibss.chandef, new_chan,
+					NL80211_CHAN_NO_HT);
+	}
+
+	/* don't join -- SSID is not there */
+	if (!wdev->wext.ibss.ssid_len)
+		return 0;
+
+	if (!netif_running(wdev->netdev))
+		return 0;
+
+	if (wdev->wext.keys)
+		wdev->wext.keys->def = wdev->wext.default_key;
+
+	wdev->wext.ibss.privacy = wdev->wext.default_key != -1;
+
+	if (wdev->wext.keys && wdev->wext.keys->def != -1) {
+		ck = kmemdup(wdev->wext.keys, sizeof(*ck), GFP_KERNEL);
+		if (!ck)
+			return -ENOMEM;
+		for (i = 0; i < 4; i++)
+			ck->params[i].key = ck->data[i];
+	}
+	err = __cfg80211_join_ibss(rdev, wdev->netdev,
+				   &wdev->wext.ibss, ck);
+	if (err)
+		kfree(ck);
+
+	return err;
+}
+
+int cfg80211_ibss_wext_siwfreq(struct net_device *dev,
+			       struct iw_request_info *info,
+			       struct iw_freq *wextfreq, char *extra)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	struct ieee80211_channel *chan = NULL;
+	int err, freq;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	if (!rdev->ops->join_ibss)
+		return -EOPNOTSUPP;
+
+	freq = cfg80211_wext_freq(wextfreq);
+	if (freq < 0)
+		return freq;
+
+	if (freq) {
+		chan = ieee80211_get_channel(wdev->wiphy, freq);
+		if (!chan)
+			return -EINVAL;
+		if (chan->flags & IEEE80211_CHAN_NO_IR ||
+		    chan->flags & IEEE80211_CHAN_DISABLED)
+			return -EINVAL;
+	}
+
+	if (wdev->wext.ibss.chandef.chan == chan)
+		return 0;
+
+	err = 0;
+	if (wdev->u.ibss.ssid_len)
+		err = cfg80211_leave_ibss(rdev, dev, true);
+
+	if (err)
+		return err;
+
+	if (chan) {
+		cfg80211_chandef_create(&wdev->wext.ibss.chandef, chan,
+					NL80211_CHAN_NO_HT);
+		wdev->wext.ibss.channel_fixed = true;
+	} else {
+		/* cfg80211_ibss_wext_join will pick one if needed */
+		wdev->wext.ibss.channel_fixed = false;
+	}
+
+	return cfg80211_ibss_wext_join(rdev, wdev);
+}
+
+int cfg80211_ibss_wext_giwfreq(struct net_device *dev,
+			       struct iw_request_info *info,
+			       struct iw_freq *freq, char *extra)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct ieee80211_channel *chan = NULL;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	if (wdev->u.ibss.current_bss)
+		chan = wdev->u.ibss.current_bss->pub.channel;
+	else if (wdev->wext.ibss.chandef.chan)
+		chan = wdev->wext.ibss.chandef.chan;
+
+	if (chan) {
+		freq->m = chan->center_freq;
+		freq->e = 6;
+		return 0;
+	}
+
+	/* no channel if not joining */
+	return -EINVAL;
+}
+
+int cfg80211_ibss_wext_siwessid(struct net_device *dev,
+				struct iw_request_info *info,
+				struct iw_point *data, char *ssid)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	size_t len = data->length;
+	int err;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	if (!rdev->ops->join_ibss)
+		return -EOPNOTSUPP;
+
+	err = 0;
+	if (wdev->u.ibss.ssid_len)
+		err = cfg80211_leave_ibss(rdev, dev, true);
+
+	if (err)
+		return err;
+
+	/* iwconfig uses nul termination in SSID.. */
+	if (len > 0 && ssid[len - 1] == '\0')
+		len--;
+
+	memcpy(wdev->u.ibss.ssid, ssid, len);
+	wdev->wext.ibss.ssid = wdev->u.ibss.ssid;
+	wdev->wext.ibss.ssid_len = len;
+
+	return cfg80211_ibss_wext_join(rdev, wdev);
+}
+
+int cfg80211_ibss_wext_giwessid(struct net_device *dev,
+				struct iw_request_info *info,
+				struct iw_point *data, char *ssid)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	data->flags = 0;
+
+	if (wdev->u.ibss.ssid_len) {
+		data->flags = 1;
+		data->length = wdev->u.ibss.ssid_len;
+		memcpy(ssid, wdev->u.ibss.ssid, data->length);
+	} else if (wdev->wext.ibss.ssid && wdev->wext.ibss.ssid_len) {
+		data->flags = 1;
+		data->length = wdev->wext.ibss.ssid_len;
+		memcpy(ssid, wdev->wext.ibss.ssid, data->length);
+	}
+
+	return 0;
+}
+
+int cfg80211_ibss_wext_siwap(struct net_device *dev,
+			     struct iw_request_info *info,
+			     struct sockaddr *ap_addr, char *extra)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	u8 *bssid = ap_addr->sa_data;
+	int err;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	if (!rdev->ops->join_ibss)
+		return -EOPNOTSUPP;
+
+	if (ap_addr->sa_family != ARPHRD_ETHER)
+		return -EINVAL;
+
+	/* automatic mode */
+	if (is_zero_ether_addr(bssid) || is_broadcast_ether_addr(bssid))
+		bssid = NULL;
+
+	if (bssid && !is_valid_ether_addr(bssid))
+		return -EINVAL;
+
+	/* both automatic */
+	if (!bssid && !wdev->wext.ibss.bssid)
+		return 0;
+
+	/* fixed already - and no change */
+	if (wdev->wext.ibss.bssid && bssid &&
+	    ether_addr_equal(bssid, wdev->wext.ibss.bssid))
+		return 0;
+
+	err = 0;
+	if (wdev->u.ibss.ssid_len)
+		err = cfg80211_leave_ibss(rdev, dev, true);
+
+	if (err)
+		return err;
+
+	if (bssid) {
+		memcpy(wdev->wext.bssid, bssid, ETH_ALEN);
+		wdev->wext.ibss.bssid = wdev->wext.bssid;
+	} else
+		wdev->wext.ibss.bssid = NULL;
+
+	return cfg80211_ibss_wext_join(rdev, wdev);
+}
+
+int cfg80211_ibss_wext_giwap(struct net_device *dev,
+			     struct iw_request_info *info,
+			     struct sockaddr *ap_addr, char *extra)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+
+	/* call only for ibss! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_ADHOC))
+		return -EINVAL;
+
+	ap_addr->sa_family = ARPHRD_ETHER;
+
+	if (wdev->u.ibss.current_bss)
+		memcpy(ap_addr->sa_data, wdev->u.ibss.current_bss->pub.bssid,
+		       ETH_ALEN);
+	else if (wdev->wext.ibss.bssid)
+		memcpy(ap_addr->sa_data, wdev->wext.ibss.bssid, ETH_ALEN);
+	else
+		eth_zero_addr(ap_addr->sa_data);
+
+	return 0;
+}
+#endif