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, 153 insertions, 0 deletions

diff --git a/fs/orangefs/acl.c b/fs/orangefs/acl.c
new file mode 100644
index 000000000..a01ef0c1b
--- /dev/null
+++ b/fs/orangefs/acl.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) 2001 Clemson University and The University of Chicago
+ *
+ * See COPYING in top-level directory.
+ */
+
+#include "protocol.h"
+#include "orangefs-kernel.h"
+#include "orangefs-bufmap.h"
+#include <linux/posix_acl_xattr.h>
+
+struct posix_acl *orangefs_get_acl(struct inode *inode, int type, bool rcu)
+{
+	struct posix_acl *acl;
+	int ret;
+	char *key = NULL, *value = NULL;
+
+	if (rcu)
+		return ERR_PTR(-ECHILD);
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		key = XATTR_NAME_POSIX_ACL_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		key = XATTR_NAME_POSIX_ACL_DEFAULT;
+		break;
+	default:
+		gossip_err("orangefs_get_acl: bogus value of type %d\n", type);
+		return ERR_PTR(-EINVAL);
+	}
+	/*
+	 * Rather than incurring a network call just to determine the exact
+	 * length of the attribute, I just allocate a max length to save on
+	 * the network call. Conceivably, we could pass NULL to
+	 * orangefs_inode_getxattr() to probe the length of the value, but
+	 * I don't do that for now.
+	 */
+	value = kmalloc(ORANGEFS_MAX_XATTR_VALUELEN, GFP_KERNEL);
+	if (!value)
+		return ERR_PTR(-ENOMEM);
+
+	gossip_debug(GOSSIP_ACL_DEBUG,
+		     "inode %pU, key %s, type %d\n",
+		     get_khandle_from_ino(inode),
+		     key,
+		     type);
+	ret = orangefs_inode_getxattr(inode, key, value,
+				      ORANGEFS_MAX_XATTR_VALUELEN);
+	/* if the key exists, convert it to an in-memory rep */
+	if (ret > 0) {
+		acl = posix_acl_from_xattr(&init_user_ns, value, ret);
+	} else if (ret == -ENODATA || ret == -ENOSYS) {
+		acl = NULL;
+	} else {
+		gossip_err("inode %pU retrieving acl's failed with error %d\n",
+			   get_khandle_from_ino(inode),
+			   ret);
+		acl = ERR_PTR(ret);
+	}
+	/* kfree(NULL) is safe, so don't worry if value ever got used */
+	kfree(value);
+	return acl;
+}
+
+int __orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int error = 0;
+	void *value = NULL;
+	size_t size = 0;
+	const char *name = NULL;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name = XATTR_NAME_POSIX_ACL_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		name = XATTR_NAME_POSIX_ACL_DEFAULT;
+		break;
+	default:
+		gossip_err("%s: invalid type %d!\n", __func__, type);
+		return -EINVAL;
+	}
+
+	gossip_debug(GOSSIP_ACL_DEBUG,
+		     "%s: inode %pU, key %s type %d\n",
+		     __func__, get_khandle_from_ino(inode),
+		     name,
+		     type);
+
+	if (acl) {
+		value = posix_acl_to_xattr(&init_user_ns, acl, &size, GFP_KERNEL);
+		if (!value)
+			return -ENOMEM;
+	}
+
+	gossip_debug(GOSSIP_ACL_DEBUG,
+		     "%s: name %s, value %p, size %zd, acl %p\n",
+		     __func__, name, value, size, acl);
+	/*
+	 * Go ahead and set the extended attribute now. NOTE: Suppose acl
+	 * was NULL, then value will be NULL and size will be 0 and that
+	 * will xlate to a removexattr. However, we don't want removexattr
+	 * complain if attributes does not exist.
+	 */
+	error = orangefs_inode_setxattr(inode, name, value, size, 0);
+
+	kfree(value);
+	if (!error)
+		set_cached_acl(inode, type, acl);
+	return error;
+}
+
+int orangefs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+		     struct posix_acl *acl, int type)
+{
+	int error;
+	struct iattr iattr;
+	int rc;
+	struct inode *inode = d_inode(dentry);
+
+	memset(&iattr, 0, sizeof iattr);
+
+	if (type == ACL_TYPE_ACCESS && acl) {
+		/*
+		 * posix_acl_update_mode checks to see if the permissions
+		 * described by the ACL can be encoded into the
+		 * object's mode. If so, it sets "acl" to NULL
+		 * and "mode" to the new desired value. It is up to
+		 * us to propagate the new mode back to the server...
+		 */
+		error = posix_acl_update_mode(&nop_mnt_idmap, inode,
+					      &iattr.ia_mode, &acl);
+		if (error) {
+			gossip_err("%s: posix_acl_update_mode err: %d\n",
+				   __func__,
+				   error);
+			return error;
+		}
+
+		if (inode->i_mode != iattr.ia_mode)
+			iattr.ia_valid = ATTR_MODE;
+
+	}
+
+	rc = __orangefs_set_acl(inode, acl, type);
+
+	if (!rc && (iattr.ia_valid == ATTR_MODE))
+		rc = __orangefs_setattr_mode(dentry, &iattr);
+
+	return rc;
+}