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, 71 insertions, 0 deletions

diff --git a/security/selinux/include/audit.h b/security/selinux/include/audit.h
new file mode 100644
index 000000000..85a531ac7
--- /dev/null
+++ b/security/selinux/include/audit.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * SELinux support for the Audit LSM hooks
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2005 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ * Copyright (C) 2006 Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
+ * Copyright (C) 2006 IBM Corporation, Timothy R. Chavez <tinytim@us.ibm.com>
+ */
+
+#ifndef _SELINUX_AUDIT_H
+#define _SELINUX_AUDIT_H
+
+#include <linux/audit.h>
+#include <linux/types.h>
+
+/**
+ * selinux_audit_rule_avc_callback - update the audit LSM rules on AVC events.
+ * @event: the AVC event
+ *
+ * Update any audit LSM rules based on the AVC event specified in @event.
+ * Returns 0 on success, negative values otherwise.
+ */
+int selinux_audit_rule_avc_callback(u32 event);
+
+/**
+ * selinux_audit_rule_init - alloc/init an selinux audit rule structure.
+ * @field: the field this rule refers to
+ * @op: the operator the rule uses
+ * @rulestr: the text "target" of the rule
+ * @rule: pointer to the new rule structure returned via this
+ * @gfp: GFP flag used for kmalloc
+ *
+ * Returns 0 if successful, -errno if not.  On success, the rule structure
+ * will be allocated internally.  The caller must free this structure with
+ * selinux_audit_rule_free() after use.
+ */
+int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule,
+			    gfp_t gfp);
+
+/**
+ * selinux_audit_rule_free - free an selinux audit rule structure.
+ * @rule: pointer to the audit rule to be freed
+ *
+ * This will free all memory associated with the given rule.
+ * If @rule is NULL, no operation is performed.
+ */
+void selinux_audit_rule_free(void *rule);
+
+/**
+ * selinux_audit_rule_match - determine if a context ID matches a rule.
+ * @prop: includes the context ID to check
+ * @field: the field this rule refers to
+ * @op: the operator the rule uses
+ * @rule: pointer to the audit rule to check against
+ *
+ * Returns 1 if the context id matches the rule, 0 if it does not, and
+ * -errno on failure.
+ */
+int selinux_audit_rule_match(struct lsm_prop *prop, u32 field, u32 op,
+			     void *rule);
+
+/**
+ * selinux_audit_rule_known - check to see if rule contains selinux fields.
+ * @rule: rule to be checked
+ * Returns 1 if there are selinux fields specified in the rule, 0 otherwise.
+ */
+int selinux_audit_rule_known(struct audit_krule *rule);
+
+#endif /* _SELINUX_AUDIT_H */