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, 132 insertions, 0 deletions

diff --git a/fs/afs/protocol_uae.h b/fs/afs/protocol_uae.h
new file mode 100644
index 000000000..1b3d1060b
--- /dev/null
+++ b/fs/afs/protocol_uae.h
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Universal AFS Error codes (UAE).
+ *
+ * Copyright (C) 2003, Daria Phoebe Brashear
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ */
+
+enum {
+	UAEPERM			= 0x2f6df00, /* Operation not permitted */
+	UAENOENT		= 0x2f6df01, /* No such file or directory */
+	UAESRCH			= 0x2f6df02, /* No such process */
+	UAEINTR			= 0x2f6df03, /* Interrupted system call */
+	UAEIO			= 0x2f6df04, /* I/O error */
+	UAENXIO			= 0x2f6df05, /* No such device or address */
+	UAE2BIG			= 0x2f6df06, /* Arg list too long */
+	UAENOEXEC		= 0x2f6df07, /* Exec format error */
+	UAEBADF			= 0x2f6df08, /* Bad file number */
+	UAECHILD		= 0x2f6df09, /* No child processes */
+	UAEAGAIN		= 0x2f6df0a, /* Try again */
+	UAENOMEM		= 0x2f6df0b, /* Out of memory */
+	UAEACCES		= 0x2f6df0c, /* Permission denied */
+	UAEFAULT		= 0x2f6df0d, /* Bad address */
+	UAENOTBLK		= 0x2f6df0e, /* Block device required */
+	UAEBUSY			= 0x2f6df0f, /* Device or resource busy */
+	UAEEXIST		= 0x2f6df10, /* File exists */
+	UAEXDEV			= 0x2f6df11, /* Cross-device link */
+	UAENODEV		= 0x2f6df12, /* No such device */
+	UAENOTDIR		= 0x2f6df13, /* Not a directory */
+	UAEISDIR		= 0x2f6df14, /* Is a directory */
+	UAEINVAL		= 0x2f6df15, /* Invalid argument */
+	UAENFILE		= 0x2f6df16, /* File table overflow */
+	UAEMFILE		= 0x2f6df17, /* Too many open files */
+	UAENOTTY		= 0x2f6df18, /* Not a typewriter */
+	UAETXTBSY		= 0x2f6df19, /* Text file busy */
+	UAEFBIG			= 0x2f6df1a, /* File too large */
+	UAENOSPC		= 0x2f6df1b, /* No space left on device */
+	UAESPIPE		= 0x2f6df1c, /* Illegal seek */
+	UAEROFS			= 0x2f6df1d, /* Read-only file system */
+	UAEMLINK		= 0x2f6df1e, /* Too many links */
+	UAEPIPE			= 0x2f6df1f, /* Broken pipe */
+	UAEDOM			= 0x2f6df20, /* Math argument out of domain of func */
+	UAERANGE		= 0x2f6df21, /* Math result not representable */
+	UAEDEADLK		= 0x2f6df22, /* Resource deadlock would occur */
+	UAENAMETOOLONG		= 0x2f6df23, /* File name too long */
+	UAENOLCK		= 0x2f6df24, /* No record locks available */
+	UAENOSYS		= 0x2f6df25, /* Function not implemented */
+	UAENOTEMPTY		= 0x2f6df26, /* Directory not empty */
+	UAELOOP			= 0x2f6df27, /* Too many symbolic links encountered */
+	UAEWOULDBLOCK		= 0x2f6df28, /* Operation would block */
+	UAENOMSG		= 0x2f6df29, /* No message of desired type */
+	UAEIDRM			= 0x2f6df2a, /* Identifier removed */
+	UAECHRNG		= 0x2f6df2b, /* Channel number out of range */
+	UAEL2NSYNC		= 0x2f6df2c, /* Level 2 not synchronized */
+	UAEL3HLT		= 0x2f6df2d, /* Level 3 halted */
+	UAEL3RST		= 0x2f6df2e, /* Level 3 reset */
+	UAELNRNG		= 0x2f6df2f, /* Link number out of range */
+	UAEUNATCH		= 0x2f6df30, /* Protocol driver not attached */
+	UAENOCSI		= 0x2f6df31, /* No CSI structure available */
+	UAEL2HLT		= 0x2f6df32, /* Level 2 halted */
+	UAEBADE			= 0x2f6df33, /* Invalid exchange */
+	UAEBADR			= 0x2f6df34, /* Invalid request descriptor */
+	UAEXFULL		= 0x2f6df35, /* Exchange full */
+	UAENOANO		= 0x2f6df36, /* No anode */
+	UAEBADRQC		= 0x2f6df37, /* Invalid request code */
+	UAEBADSLT		= 0x2f6df38, /* Invalid slot */
+	UAEBFONT		= 0x2f6df39, /* Bad font file format */
+	UAENOSTR		= 0x2f6df3a, /* Device not a stream */
+	UAENODATA		= 0x2f6df3b, /* No data available */
+	UAETIME			= 0x2f6df3c, /* Timer expired */
+	UAENOSR			= 0x2f6df3d, /* Out of streams resources */
+	UAENONET		= 0x2f6df3e, /* Machine is not on the network */
+	UAENOPKG		= 0x2f6df3f, /* Package not installed */
+	UAEREMOTE		= 0x2f6df40, /* Object is remote */
+	UAENOLINK		= 0x2f6df41, /* Link has been severed */
+	UAEADV			= 0x2f6df42, /* Advertise error */
+	UAESRMNT		= 0x2f6df43, /* Srmount error */
+	UAECOMM			= 0x2f6df44, /* Communication error on send */
+	UAEPROTO		= 0x2f6df45, /* Protocol error */
+	UAEMULTIHOP		= 0x2f6df46, /* Multihop attempted */
+	UAEDOTDOT		= 0x2f6df47, /* RFS specific error */
+	UAEBADMSG		= 0x2f6df48, /* Not a data message */
+	UAEOVERFLOW		= 0x2f6df49, /* Value too large for defined data type */
+	UAENOTUNIQ		= 0x2f6df4a, /* Name not unique on network */
+	UAEBADFD		= 0x2f6df4b, /* File descriptor in bad state */
+	UAEREMCHG		= 0x2f6df4c, /* Remote address changed */
+	UAELIBACC		= 0x2f6df4d, /* Can not access a needed shared library */
+	UAELIBBAD		= 0x2f6df4e, /* Accessing a corrupted shared library */
+	UAELIBSCN		= 0x2f6df4f, /* .lib section in a.out corrupted */
+	UAELIBMAX		= 0x2f6df50, /* Attempting to link in too many shared libraries */
+	UAELIBEXEC		= 0x2f6df51, /* Cannot exec a shared library directly */
+	UAEILSEQ		= 0x2f6df52, /* Illegal byte sequence */
+	UAERESTART		= 0x2f6df53, /* Interrupted system call should be restarted */
+	UAESTRPIPE		= 0x2f6df54, /* Streams pipe error */
+	UAEUSERS		= 0x2f6df55, /* Too many users */
+	UAENOTSOCK		= 0x2f6df56, /* Socket operation on non-socket */
+	UAEDESTADDRREQ		= 0x2f6df57, /* Destination address required */
+	UAEMSGSIZE		= 0x2f6df58, /* Message too long */
+	UAEPROTOTYPE		= 0x2f6df59, /* Protocol wrong type for socket */
+	UAENOPROTOOPT		= 0x2f6df5a, /* Protocol not available */
+	UAEPROTONOSUPPORT	= 0x2f6df5b, /* Protocol not supported */
+	UAESOCKTNOSUPPORT	= 0x2f6df5c, /* Socket type not supported */
+	UAEOPNOTSUPP		= 0x2f6df5d, /* Operation not supported on transport endpoint */
+	UAEPFNOSUPPORT		= 0x2f6df5e, /* Protocol family not supported */
+	UAEAFNOSUPPORT		= 0x2f6df5f, /* Address family not supported by protocol */
+	UAEADDRINUSE		= 0x2f6df60, /* Address already in use */
+	UAEADDRNOTAVAIL		= 0x2f6df61, /* Cannot assign requested address */
+	UAENETDOWN		= 0x2f6df62, /* Network is down */
+	UAENETUNREACH		= 0x2f6df63, /* Network is unreachable */
+	UAENETRESET		= 0x2f6df64, /* Network dropped connection because of reset */
+	UAECONNABORTED		= 0x2f6df65, /* Software caused connection abort */
+	UAECONNRESET		= 0x2f6df66, /* Connection reset by peer */
+	UAENOBUFS		= 0x2f6df67, /* No buffer space available */
+	UAEISCONN		= 0x2f6df68, /* Transport endpoint is already connected */
+	UAENOTCONN		= 0x2f6df69, /* Transport endpoint is not connected */
+	UAESHUTDOWN		= 0x2f6df6a, /* Cannot send after transport endpoint shutdown */
+	UAETOOMANYREFS		= 0x2f6df6b, /* Too many references: cannot splice */
+	UAETIMEDOUT		= 0x2f6df6c, /* Connection timed out */
+	UAECONNREFUSED		= 0x2f6df6d, /* Connection refused */
+	UAEHOSTDOWN		= 0x2f6df6e, /* Host is down */
+	UAEHOSTUNREACH		= 0x2f6df6f, /* No route to host */
+	UAEALREADY		= 0x2f6df70, /* Operation already in progress */
+	UAEINPROGRESS		= 0x2f6df71, /* Operation now in progress */
+	UAESTALE		= 0x2f6df72, /* Stale NFS file handle */
+	UAEUCLEAN		= 0x2f6df73, /* Structure needs cleaning */
+	UAENOTNAM		= 0x2f6df74, /* Not a XENIX named type file */
+	UAENAVAIL		= 0x2f6df75, /* No XENIX semaphores available */
+	UAEISNAM		= 0x2f6df76, /* Is a named type file */
+	UAEREMOTEIO		= 0x2f6df77, /* Remote I/O error */
+	UAEDQUOT		= 0x2f6df78, /* Quota exceeded */
+	UAENOMEDIUM		= 0x2f6df79, /* No medium found */
+	UAEMEDIUMTYPE		= 0x2f6df7a, /* Wrong medium type */
+};