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, 184 insertions, 0 deletions

diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
new file mode 100644
index 000000000..c0f97f363
--- /dev/null
+++ b/include/net/netns/sctp.h
@@ -0,0 +1,184 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NETNS_SCTP_H__
+#define __NETNS_SCTP_H__
+
+#include <linux/timer.h>
+#include <net/snmp.h>
+
+struct sock;
+struct proc_dir_entry;
+struct sctp_mib;
+struct ctl_table_header;
+
+struct netns_sctp {
+	DEFINE_SNMP_STAT(struct sctp_mib, sctp_statistics);
+
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *proc_net_sctp;
+#endif
+#ifdef CONFIG_SYSCTL
+	struct ctl_table_header *sysctl_header;
+#endif
+	/* This is the global socket data structure used for responding to
+	 * the Out-of-the-blue (OOTB) packets.  A control sock will be created
+	 * for this socket at the initialization time.
+	 */
+	struct sock *ctl_sock;
+
+	/* UDP tunneling listening sock. */
+	struct sock *udp4_sock;
+	struct sock *udp6_sock;
+	/* UDP tunneling listening port. */
+	int udp_port;
+	/* UDP tunneling remote encap port. */
+	int encap_port;
+
+	/* This is the global local address list.
+	 * We actively maintain this complete list of addresses on
+	 * the system by catching address add/delete events.
+	 *
+	 * It is a list of sctp_sockaddr_entry.
+	 */
+	struct list_head local_addr_list;
+	struct list_head addr_waitq;
+	struct timer_list addr_wq_timer;
+	struct list_head auto_asconf_splist;
+	/* Lock that protects both addr_waitq and auto_asconf_splist */
+	spinlock_t addr_wq_lock;
+
+	/* Lock that protects the local_addr_list writers */
+	spinlock_t local_addr_lock;
+
+	/* RFC2960 Section 14. Suggested SCTP Protocol Parameter Values
+	 *
+	 * The following protocol parameters are RECOMMENDED:
+	 *
+	 * RTO.Initial		    - 3	 seconds
+	 * RTO.Min		    - 1	 second
+	 * RTO.Max		   -  60 seconds
+	 * RTO.Alpha		    - 1/8  (3 when converted to right shifts.)
+	 * RTO.Beta		    - 1/4  (2 when converted to right shifts.)
+	 */
+	unsigned int rto_initial;
+	unsigned int rto_min;
+	unsigned int rto_max;
+
+	/* Note: rto_alpha and rto_beta are really defined as inverse
+	 * powers of two to facilitate integer operations.
+	 */
+	int rto_alpha;
+	int rto_beta;
+
+	/* Max.Burst		    - 4 */
+	int max_burst;
+
+	/* Whether Cookie Preservative is enabled(1) or not(0) */
+	int cookie_preserve_enable;
+
+	/* Whether cookie authentication is enabled(1) or not(0) */
+	int cookie_auth_enable;
+
+	/* Valid.Cookie.Life	    - 60  seconds  */
+	unsigned int valid_cookie_life;
+
+	/* Delayed SACK timeout  200ms default*/
+	unsigned int sack_timeout;
+
+	/* HB.interval		    - 30 seconds  */
+	unsigned int hb_interval;
+
+	/* The interval for PLPMTUD probe timer */
+	unsigned int probe_interval;
+
+	/* Association.Max.Retrans  - 10 attempts
+	 * Path.Max.Retrans	    - 5	 attempts (per destination address)
+	 * Max.Init.Retransmits	    - 8	 attempts
+	 */
+	int max_retrans_association;
+	int max_retrans_path;
+	int max_retrans_init;
+	/* Potentially-Failed.Max.Retrans sysctl value
+	 * taken from:
+	 * http://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05
+	 */
+	int pf_retrans;
+
+	/* Primary.Switchover.Max.Retrans sysctl value
+	 * taken from:
+	 * https://tools.ietf.org/html/rfc7829
+	 */
+	int ps_retrans;
+
+	/*
+	 * Disable Potentially-Failed feature, the feature is enabled by default
+	 * pf_enable	-  0  : disable pf
+	 *		- >0  : enable pf
+	 */
+	int pf_enable;
+
+	/*
+	 * Disable Potentially-Failed state exposure, ignored by default
+	 * pf_expose	-  0  : compatible with old applications (by default)
+	 *		-  1  : disable pf state exposure
+	 *		-  2  : enable  pf state exposure
+	 */
+	int pf_expose;
+
+	/*
+	 * Policy for performing sctp/socket accounting
+	 * 0   - do socket level accounting, all assocs share sk_sndbuf
+	 * 1   - do sctp accounting, each asoc may use sk_sndbuf bytes
+	 */
+	int sndbuf_policy;
+
+	/*
+	 * Policy for performing sctp/socket accounting
+	 * 0   - do socket level accounting, all assocs share sk_rcvbuf
+	 * 1   - do sctp accounting, each asoc may use sk_rcvbuf bytes
+	 */
+	int rcvbuf_policy;
+
+	int default_auto_asconf;
+
+	/* Flag to indicate if addip is enabled. */
+	int addip_enable;
+	int addip_noauth;
+
+	/* Flag to indicate if PR-SCTP is enabled. */
+	int prsctp_enable;
+
+	/* Flag to indicate if PR-CONFIG is enabled. */
+	int reconf_enable;
+
+	/* Flag to indicate if SCTP-AUTH is enabled */
+	int auth_enable;
+
+	/* Flag to indicate if stream interleave is enabled */
+	int intl_enable;
+
+	/* Flag to indicate if ecn is enabled */
+	int ecn_enable;
+
+	/*
+	 * Policy to control SCTP IPv4 address scoping
+	 * 0   - Disable IPv4 address scoping
+	 * 1   - Enable IPv4 address scoping
+	 * 2   - Selectively allow only IPv4 private addresses
+	 * 3   - Selectively allow only IPv4 link local address
+	 */
+	int scope_policy;
+
+	/* Threshold for rwnd update SACKS.  Receive buffer shifted this many
+	 * bits is an indicator of when to send and window update SACK.
+	 */
+	int rwnd_upd_shift;
+
+	/* Threshold for autoclose timeout, in seconds. */
+	unsigned long max_autoclose;
+
+#ifdef CONFIG_NET_L3_MASTER_DEV
+	int l3mdev_accept;
+#endif
+};
+
+#endif /* __NETNS_SCTP_H__ */