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, 378 insertions, 0 deletions

diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c
new file mode 100644
index 000000000..b5914f365
--- /dev/null
+++ b/net/wireless/wext-sme.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cfg80211 wext compat for managed mode.
+ *
+ * Copyright 2009	Johannes Berg <johannes@sipsolutions.net>
+ * Copyright (C) 2009, 2020-2023 Intel Corporation
+ */
+
+#include <linux/export.h>
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/slab.h>
+#include <net/cfg80211.h>
+#include <net/cfg80211-wext.h>
+#include "wext-compat.h"
+#include "nl80211.h"
+
+int cfg80211_mgd_wext_connect(struct cfg80211_registered_device *rdev,
+			      struct wireless_dev *wdev)
+{
+	struct cfg80211_cached_keys *ck = NULL;
+	const u8 *prev_bssid = NULL;
+	int err, i;
+
+	ASSERT_RTNL();
+	lockdep_assert_wiphy(wdev->wiphy);
+
+	if (!netif_running(wdev->netdev))
+		return 0;
+
+	wdev->wext.connect.ie = wdev->wext.ie;
+	wdev->wext.connect.ie_len = wdev->wext.ie_len;
+
+	/* Use default background scan period */
+	wdev->wext.connect.bg_scan_period = -1;
+
+	if (wdev->wext.keys) {
+		wdev->wext.keys->def = wdev->wext.default_key;
+		if (wdev->wext.default_key != -1)
+			wdev->wext.connect.privacy = true;
+	}
+
+	if (!wdev->wext.connect.ssid_len)
+		return 0;
+
+	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];
+	}
+
+	if (wdev->wext.prev_bssid_valid)
+		prev_bssid = wdev->wext.prev_bssid;
+
+	err = cfg80211_connect(rdev, wdev->netdev,
+			       &wdev->wext.connect, ck, prev_bssid);
+	if (err)
+		kfree_sensitive(ck);
+
+	return err;
+}
+
+int cfg80211_mgd_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 station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	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_DISABLED)
+			return -EINVAL;
+	}
+
+	if (wdev->conn) {
+		bool event = true;
+
+		if (wdev->wext.connect.channel == chan)
+			return 0;
+
+		/* if SSID set, we'll try right again, avoid event */
+		if (wdev->wext.connect.ssid_len)
+			event = false;
+		err = cfg80211_disconnect(rdev, dev,
+					  WLAN_REASON_DEAUTH_LEAVING, event);
+		if (err)
+			return err;
+	}
+
+	wdev->wext.connect.channel = chan;
+	return cfg80211_mgd_wext_connect(rdev, wdev);
+}
+
+int cfg80211_mgd_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 station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	if (wdev->valid_links)
+		return -EOPNOTSUPP;
+
+	if (wdev->links[0].client.current_bss)
+		chan = wdev->links[0].client.current_bss->pub.channel;
+	else if (wdev->wext.connect.channel)
+		chan = wdev->wext.connect.channel;
+
+	if (chan) {
+		freq->m = chan->center_freq;
+		freq->e = 6;
+		return 0;
+	}
+
+	/* no channel if not joining */
+	return -EINVAL;
+}
+
+int cfg80211_mgd_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 station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	if (!data->flags)
+		len = 0;
+
+	/* iwconfig uses nul termination in SSID.. */
+	if (len > 0 && ssid[len - 1] == '\0')
+		len--;
+
+	if (wdev->conn) {
+		bool event = true;
+
+		if (wdev->wext.connect.ssid && len &&
+		    len == wdev->wext.connect.ssid_len &&
+		    memcmp(wdev->wext.connect.ssid, ssid, len) == 0)
+			return 0;
+
+		/* if SSID set now, we'll try to connect, avoid event */
+		if (len)
+			event = false;
+		err = cfg80211_disconnect(rdev, dev,
+					  WLAN_REASON_DEAUTH_LEAVING, event);
+		if (err)
+			return err;
+	}
+
+	wdev->wext.prev_bssid_valid = false;
+	wdev->wext.connect.ssid = wdev->wext.ssid;
+	memcpy(wdev->wext.ssid, ssid, len);
+	wdev->wext.connect.ssid_len = len;
+
+	wdev->wext.connect.crypto.control_port = false;
+	wdev->wext.connect.crypto.control_port_ethertype =
+					cpu_to_be16(ETH_P_PAE);
+
+	return cfg80211_mgd_wext_connect(rdev, wdev);
+}
+
+int cfg80211_mgd_wext_giwessid(struct net_device *dev,
+			       struct iw_request_info *info,
+			       struct iw_point *data, char *ssid)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	int ret = 0;
+
+	/* call only for station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	if (wdev->valid_links)
+		return -EINVAL;
+
+	data->flags = 0;
+
+	if (wdev->links[0].client.current_bss) {
+		const struct element *ssid_elem;
+
+		rcu_read_lock();
+		ssid_elem = ieee80211_bss_get_elem(
+				&wdev->links[0].client.current_bss->pub,
+				WLAN_EID_SSID);
+		if (ssid_elem) {
+			data->flags = 1;
+			data->length = ssid_elem->datalen;
+			if (data->length > IW_ESSID_MAX_SIZE)
+				ret = -EINVAL;
+			else
+				memcpy(ssid, ssid_elem->data, data->length);
+		}
+		rcu_read_unlock();
+	} else if (wdev->wext.connect.ssid && wdev->wext.connect.ssid_len) {
+		data->flags = 1;
+		data->length = wdev->wext.connect.ssid_len;
+		memcpy(ssid, wdev->wext.connect.ssid, data->length);
+	}
+
+	return ret;
+}
+
+int cfg80211_mgd_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 station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	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 (wdev->conn) {
+		/* both automatic */
+		if (!bssid && !wdev->wext.connect.bssid)
+			return 0;
+
+		/* fixed already - and no change */
+		if (wdev->wext.connect.bssid && bssid &&
+		    ether_addr_equal(bssid, wdev->wext.connect.bssid))
+			return 0;
+
+		err = cfg80211_disconnect(rdev, dev,
+					  WLAN_REASON_DEAUTH_LEAVING, false);
+		if (err)
+			return err;
+	}
+
+	if (bssid) {
+		memcpy(wdev->wext.bssid, bssid, ETH_ALEN);
+		wdev->wext.connect.bssid = wdev->wext.bssid;
+	} else
+		wdev->wext.connect.bssid = NULL;
+
+	return cfg80211_mgd_wext_connect(rdev, wdev);
+}
+
+int cfg80211_mgd_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 station! */
+	if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
+		return -EINVAL;
+
+	ap_addr->sa_family = ARPHRD_ETHER;
+
+	if (wdev->valid_links)
+		return -EOPNOTSUPP;
+
+	if (wdev->links[0].client.current_bss)
+		memcpy(ap_addr->sa_data,
+		       wdev->links[0].client.current_bss->pub.bssid,
+		       ETH_ALEN);
+	else
+		eth_zero_addr(ap_addr->sa_data);
+
+	return 0;
+}
+
+int cfg80211_wext_siwgenie(struct net_device *dev,
+			   struct iw_request_info *info,
+			   union iwreq_data *wrqu, char *extra)
+{
+	struct iw_point *data = &wrqu->data;
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+	int ie_len = data->length;
+	u8 *ie = extra;
+
+	if (wdev->iftype != NL80211_IFTYPE_STATION)
+		return -EOPNOTSUPP;
+
+	if (!ie_len)
+		ie = NULL;
+
+	guard(wiphy)(wdev->wiphy);
+
+	/* no change */
+	if (wdev->wext.ie_len == ie_len &&
+	    memcmp(wdev->wext.ie, ie, ie_len) == 0)
+		return 0;
+
+	if (ie_len) {
+		const struct element *elem;
+
+		for_each_element(elem, extra, ie_len) {
+			/* nothing */
+		}
+
+		if (!for_each_element_completed(elem, extra, ie_len))
+			return -EINVAL;
+
+		ie = kmemdup(extra, ie_len, GFP_KERNEL);
+		if (!ie)
+			return -ENOMEM;
+	} else {
+		ie = NULL;
+	}
+
+	kfree(wdev->wext.ie);
+	wdev->wext.ie = ie;
+	wdev->wext.ie_len = ie_len;
+
+	if (wdev->conn)
+		return cfg80211_disconnect(rdev, dev,
+					   WLAN_REASON_DEAUTH_LEAVING, false);
+
+	/* userspace better not think we'll reconnect */
+	return 0;
+}
+
+int cfg80211_wext_siwmlme(struct net_device *dev,
+			  struct iw_request_info *info,
+			  union iwreq_data *wrqu, char *extra)
+{
+	struct wireless_dev *wdev = dev->ieee80211_ptr;
+	struct iw_mlme *mlme = (struct iw_mlme *)extra;
+	struct cfg80211_registered_device *rdev;
+
+	if (!wdev)
+		return -EOPNOTSUPP;
+
+	rdev = wiphy_to_rdev(wdev->wiphy);
+
+	if (wdev->iftype != NL80211_IFTYPE_STATION)
+		return -EINVAL;
+
+	if (mlme->addr.sa_family != ARPHRD_ETHER)
+		return -EINVAL;
+
+	guard(wiphy)(&rdev->wiphy);
+
+	switch (mlme->cmd) {
+	case IW_MLME_DEAUTH:
+	case IW_MLME_DISASSOC:
+		return cfg80211_disconnect(rdev, dev, mlme->reason_code, true);
+	default:
+		return -EOPNOTSUPP;
+	}
+}