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, 643 insertions, 0 deletions

diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
new file mode 100644
index 000000000..51fcba2e6
--- /dev/null
+++ b/fs/hfsplus/dir.c
@@ -0,0 +1,643 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hfsplus/dir.c
+ *
+ * Copyright (C) 2001
+ * Brad Boyer (flar@allandria.com)
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ *
+ * Handling of directories
+ */
+
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/nls.h>
+
+#include "hfsplus_fs.h"
+#include "hfsplus_raw.h"
+#include "xattr.h"
+
+static inline void hfsplus_instantiate(struct dentry *dentry,
+				       struct inode *inode, u32 cnid)
+{
+	dentry->d_fsdata = (void *)(unsigned long)cnid;
+	d_instantiate(dentry, inode);
+}
+
+/* Find the entry inside dir named dentry->d_name */
+static struct dentry *hfsplus_lookup(struct inode *dir, struct dentry *dentry,
+				     unsigned int flags)
+{
+	struct inode *inode = NULL;
+	struct hfs_find_data fd;
+	struct super_block *sb;
+	hfsplus_cat_entry entry;
+	int err;
+	u32 cnid, linkid = 0;
+	u16 type;
+
+	sb = dir->i_sb;
+
+	dentry->d_fsdata = NULL;
+	err = hfs_find_init(HFSPLUS_SB(sb)->cat_tree, &fd);
+	if (err)
+		return ERR_PTR(err);
+	err = hfsplus_cat_build_key(sb, fd.search_key, dir->i_ino,
+			&dentry->d_name);
+	if (unlikely(err < 0))
+		goto fail;
+again:
+	err = hfsplus_brec_read_cat(&fd, &entry);
+	if (err) {
+		if (err == -ENOENT) {
+			hfs_find_exit(&fd);
+			/* No such entry */
+			inode = NULL;
+			goto out;
+		}
+		goto fail;
+	}
+	type = be16_to_cpu(entry.type);
+	if (type == HFSPLUS_FOLDER) {
+		if (fd.entrylength < sizeof(struct hfsplus_cat_folder)) {
+			err = -EIO;
+			goto fail;
+		}
+		cnid = be32_to_cpu(entry.folder.id);
+		dentry->d_fsdata = (void *)(unsigned long)cnid;
+	} else if (type == HFSPLUS_FILE) {
+		if (fd.entrylength < sizeof(struct hfsplus_cat_file)) {
+			err = -EIO;
+			goto fail;
+		}
+		cnid = be32_to_cpu(entry.file.id);
+		if (entry.file.user_info.fdType ==
+				cpu_to_be32(HFSP_HARDLINK_TYPE) &&
+				entry.file.user_info.fdCreator ==
+				cpu_to_be32(HFSP_HFSPLUS_CREATOR) &&
+				HFSPLUS_SB(sb)->hidden_dir &&
+				(entry.file.create_date ==
+					HFSPLUS_I(HFSPLUS_SB(sb)->hidden_dir)->
+						create_date ||
+				entry.file.create_date ==
+					HFSPLUS_I(d_inode(sb->s_root))->
+						create_date)) {
+			struct qstr str;
+			char name[32];
+
+			if (dentry->d_fsdata) {
+				/*
+				 * We found a link pointing to another link,
+				 * so ignore it and treat it as regular file.
+				 */
+				cnid = (unsigned long)dentry->d_fsdata;
+				linkid = 0;
+			} else {
+				dentry->d_fsdata = (void *)(unsigned long)cnid;
+				linkid =
+					be32_to_cpu(entry.file.permissions.dev);
+				str.len = sprintf(name, "iNode%d", linkid);
+				str.name = name;
+				err = hfsplus_cat_build_key(sb, fd.search_key,
+					HFSPLUS_SB(sb)->hidden_dir->i_ino,
+					&str);
+				if (unlikely(err < 0))
+					goto fail;
+				goto again;
+			}
+		} else if (!dentry->d_fsdata)
+			dentry->d_fsdata = (void *)(unsigned long)cnid;
+	} else {
+		pr_err("invalid catalog entry type in lookup\n");
+		err = -EIO;
+		goto fail;
+	}
+	hfs_find_exit(&fd);
+	inode = hfsplus_iget(dir->i_sb, cnid);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+	if (S_ISREG(inode->i_mode))
+		HFSPLUS_I(inode)->linkid = linkid;
+out:
+	return d_splice_alias(inode, dentry);
+fail:
+	hfs_find_exit(&fd);
+	return ERR_PTR(err);
+}
+
+static int hfsplus_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	int len, err;
+	char *strbuf;
+	hfsplus_cat_entry entry;
+	struct hfs_find_data fd;
+	struct hfsplus_readdir_data *rd;
+	u16 type;
+
+	if (file->f_pos >= inode->i_size)
+		return 0;
+
+	err = hfs_find_init(HFSPLUS_SB(sb)->cat_tree, &fd);
+	if (err)
+		return err;
+	strbuf = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_MAX_STRLEN + 1, GFP_KERNEL);
+	if (!strbuf) {
+		err = -ENOMEM;
+		goto out;
+	}
+	hfsplus_cat_build_key_with_cnid(sb, fd.search_key, inode->i_ino);
+	err = hfs_brec_find(&fd, hfs_find_rec_by_key);
+	if (err)
+		goto out;
+
+	if (ctx->pos == 0) {
+		/* This is completely artificial... */
+		if (!dir_emit_dot(file, ctx))
+			goto out;
+		ctx->pos = 1;
+	}
+	if (ctx->pos == 1) {
+		if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
+			err = -EIO;
+			goto out;
+		}
+
+		hfs_bnode_read(fd.bnode, &entry, fd.entryoffset,
+			fd.entrylength);
+		if (be16_to_cpu(entry.type) != HFSPLUS_FOLDER_THREAD) {
+			pr_err("bad catalog folder thread\n");
+			err = -EIO;
+			goto out;
+		}
+		if (fd.entrylength < HFSPLUS_MIN_THREAD_SZ) {
+			pr_err("truncated catalog thread\n");
+			err = -EIO;
+			goto out;
+		}
+		if (!dir_emit(ctx, "..", 2,
+			    be32_to_cpu(entry.thread.parentID), DT_DIR))
+			goto out;
+		ctx->pos = 2;
+	}
+	if (ctx->pos >= inode->i_size)
+		goto out;
+	rd = file->private_data;
+	if (rd && rd->pos == ctx->pos) {
+		memcpy(fd.search_key, &rd->key, sizeof(struct hfsplus_cat_key));
+		err = hfs_brec_find(&fd, hfs_find_rec_by_key);
+		if (err == -ENOENT)
+			err = hfs_brec_goto(&fd, 1);
+	} else {
+		err = hfs_brec_goto(&fd, ctx->pos - 1);
+	}
+	if (err)
+		goto out;
+	for (;;) {
+		if (be32_to_cpu(fd.key->cat.parent) != inode->i_ino) {
+			pr_err("walked past end of dir\n");
+			err = -EIO;
+			goto out;
+		}
+
+		if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
+			err = -EIO;
+			goto out;
+		}
+
+		hfs_bnode_read(fd.bnode, &entry, fd.entryoffset,
+			fd.entrylength);
+		type = be16_to_cpu(entry.type);
+		len = NLS_MAX_CHARSET_SIZE * HFSPLUS_MAX_STRLEN;
+		err = hfsplus_uni2asc_str(sb, &fd.key->cat.name, strbuf, &len);
+		if (err)
+			goto out;
+		if (type == HFSPLUS_FOLDER) {
+			if (fd.entrylength <
+					sizeof(struct hfsplus_cat_folder)) {
+				pr_err("small dir entry\n");
+				err = -EIO;
+				goto out;
+			}
+			if (HFSPLUS_SB(sb)->hidden_dir &&
+			    HFSPLUS_SB(sb)->hidden_dir->i_ino ==
+					be32_to_cpu(entry.folder.id))
+				goto next;
+			if (!dir_emit(ctx, strbuf, len,
+				    be32_to_cpu(entry.folder.id), DT_DIR))
+				break;
+		} else if (type == HFSPLUS_FILE) {
+			u16 mode;
+			unsigned type = DT_UNKNOWN;
+
+			if (fd.entrylength < sizeof(struct hfsplus_cat_file)) {
+				pr_err("small file entry\n");
+				err = -EIO;
+				goto out;
+			}
+
+			mode = be16_to_cpu(entry.file.permissions.mode);
+			if (S_ISREG(mode))
+				type = DT_REG;
+			else if (S_ISLNK(mode))
+				type = DT_LNK;
+			else if (S_ISFIFO(mode))
+				type = DT_FIFO;
+			else if (S_ISCHR(mode))
+				type = DT_CHR;
+			else if (S_ISBLK(mode))
+				type = DT_BLK;
+			else if (S_ISSOCK(mode))
+				type = DT_SOCK;
+
+			if (!dir_emit(ctx, strbuf, len,
+				      be32_to_cpu(entry.file.id), type))
+				break;
+		} else {
+			pr_err("bad catalog entry type\n");
+			err = -EIO;
+			goto out;
+		}
+next:
+		ctx->pos++;
+		if (ctx->pos >= inode->i_size)
+			goto out;
+		err = hfs_brec_goto(&fd, 1);
+		if (err)
+			goto out;
+	}
+	if (!rd) {
+		rd = kmalloc_obj(struct hfsplus_readdir_data);
+		if (!rd) {
+			err = -ENOMEM;
+			goto out;
+		}
+		file->private_data = rd;
+	}
+	rd->pos = ctx->pos;
+	memcpy(&rd->key, fd.key, sizeof(struct hfsplus_cat_key));
+out:
+	kfree(strbuf);
+	hfs_find_exit(&fd);
+	return err;
+}
+
+static int hfsplus_dir_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
+			struct dentry *dst_dentry)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dst_dir->i_sb);
+	struct inode *inode = d_inode(src_dentry);
+	struct inode *src_dir = d_inode(src_dentry->d_parent);
+	struct qstr str;
+	char name[32];
+	u32 cnid, id;
+	int res;
+
+	if (HFSPLUS_IS_RSRC(inode))
+		return -EPERM;
+	if (!S_ISREG(inode->i_mode))
+		return -EPERM;
+
+	hfs_dbg("src_dir->i_ino %llu, dst_dir->i_ino %llu, inode->i_ino %llu\n",
+		src_dir->i_ino, dst_dir->i_ino, inode->i_ino);
+
+	mutex_lock(&sbi->vh_mutex);
+	if (inode->i_ino == (u32)(unsigned long)src_dentry->d_fsdata) {
+		for (;;) {
+			get_random_bytes(&id, sizeof(cnid));
+			id &= 0x3fffffff;
+			str.name = name;
+			str.len = sprintf(name, "iNode%d", id);
+			res = hfsplus_rename_cat(inode->i_ino,
+						 src_dir, &src_dentry->d_name,
+						 sbi->hidden_dir, &str);
+			if (!res)
+				break;
+			if (res != -EEXIST)
+				goto out;
+		}
+		HFSPLUS_I(inode)->linkid = id;
+		cnid = sbi->next_cnid++;
+		src_dentry->d_fsdata = (void *)(unsigned long)cnid;
+		res = hfsplus_create_cat(cnid, src_dir,
+					 &src_dentry->d_name, inode);
+		if (res)
+			/* panic? */
+			goto out;
+		sbi->file_count++;
+	}
+	cnid = sbi->next_cnid++;
+	res = hfsplus_create_cat(cnid, dst_dir, &dst_dentry->d_name, inode);
+	if (res)
+		goto out;
+
+	inc_nlink(inode);
+	hfsplus_instantiate(dst_dentry, inode, cnid);
+	ihold(inode);
+	inode_set_ctime_current(inode);
+	mark_inode_dirty(inode);
+	sbi->file_count++;
+	hfsplus_mark_mdb_dirty(dst_dir->i_sb);
+
+	res = hfsplus_cat_write_inode(src_dir);
+	if (res)
+		goto out;
+
+	res = hfsplus_cat_write_inode(dst_dir);
+	if (res)
+		goto out;
+
+	res = hfsplus_cat_write_inode(sbi->hidden_dir);
+	if (res)
+		goto out;
+
+	res = hfsplus_cat_write_inode(inode);
+
+out:
+	mutex_unlock(&sbi->vh_mutex);
+	return res;
+}
+
+static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
+	struct inode *inode = d_inode(dentry);
+	struct qstr str;
+	char name[32];
+	u32 cnid;
+	int res;
+
+	if (HFSPLUS_IS_RSRC(inode))
+		return -EPERM;
+
+	hfs_dbg("dir->i_ino %llu, inode->i_ino %llu\n",
+		dir->i_ino, inode->i_ino);
+
+	mutex_lock(&sbi->vh_mutex);
+	cnid = (u32)(unsigned long)dentry->d_fsdata;
+	if (inode->i_ino == cnid &&
+	    atomic_read(&HFSPLUS_I(inode)->opencnt)) {
+		str.name = name;
+		str.len = sprintf(name, "temp%llu", inode->i_ino);
+		res = hfsplus_rename_cat(inode->i_ino,
+					 dir, &dentry->d_name,
+					 sbi->hidden_dir, &str);
+		if (!res) {
+			inode->i_flags |= S_DEAD;
+			drop_nlink(inode);
+		}
+		goto out;
+	}
+	res = hfsplus_delete_cat(cnid, dir, &dentry->d_name);
+	if (res)
+		goto out;
+
+	if (inode->i_nlink > 0)
+		drop_nlink(inode);
+	if (inode->i_ino == cnid)
+		clear_nlink(inode);
+	if (!inode->i_nlink) {
+		if (inode->i_ino != cnid) {
+			sbi->file_count--;
+			if (!atomic_read(&HFSPLUS_I(inode)->opencnt)) {
+				res = hfsplus_delete_cat(inode->i_ino,
+							 sbi->hidden_dir,
+							 NULL);
+				if (!res)
+					hfsplus_delete_inode(inode);
+			} else
+				inode->i_flags |= S_DEAD;
+		} else
+			hfsplus_delete_inode(inode);
+	} else
+		sbi->file_count--;
+	inode_set_ctime_current(inode);
+	mark_inode_dirty(inode);
+out:
+	if (!res) {
+		res = hfsplus_cat_write_inode(dir);
+		if (!res) {
+			res = hfsplus_cat_write_inode(sbi->hidden_dir);
+			if (!res)
+				res = hfsplus_cat_write_inode(inode);
+		}
+	}
+
+	mutex_unlock(&sbi->vh_mutex);
+	return res;
+}
+
+static int hfsplus_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
+	struct inode *inode = d_inode(dentry);
+	int res;
+
+	if (inode->i_size != 2)
+		return -ENOTEMPTY;
+
+	mutex_lock(&sbi->vh_mutex);
+	res = hfsplus_delete_cat(inode->i_ino, dir, &dentry->d_name);
+	if (res)
+		goto out;
+	clear_nlink(inode);
+	inode_set_ctime_current(inode);
+	hfsplus_delete_inode(inode);
+	mark_inode_dirty(inode);
+
+	res = hfsplus_cat_write_inode(dir);
+out:
+	mutex_unlock(&sbi->vh_mutex);
+	return res;
+}
+
+static int hfsplus_symlink(struct mnt_idmap *idmap, struct inode *dir,
+			   struct dentry *dentry, const char *symname)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
+	struct inode *inode;
+	int res = -ENOMEM;
+
+	mutex_lock(&sbi->vh_mutex);
+	inode = hfsplus_new_inode(dir->i_sb, dir, S_IFLNK | S_IRWXUGO);
+	if (!inode)
+		goto out;
+
+	hfs_dbg("dir->i_ino %llu, inode->i_ino %llu\n",
+		dir->i_ino, inode->i_ino);
+
+	res = page_symlink(inode, symname, strlen(symname) + 1);
+	if (res)
+		goto out_err;
+
+	res = hfsplus_create_cat(inode->i_ino, dir, &dentry->d_name, inode);
+	if (res)
+		goto out_err;
+
+	res = hfsplus_init_security(inode, dir, &dentry->d_name);
+	if (res == -EOPNOTSUPP)
+		res = 0; /* Operation is not supported. */
+	else if (res) {
+		/* Try to delete anyway without error analysis. */
+		hfsplus_delete_cat(inode->i_ino, dir, &dentry->d_name);
+		goto out_err;
+	}
+
+	hfsplus_instantiate(dentry, inode, inode->i_ino);
+	mark_inode_dirty(inode);
+
+	res = hfsplus_cat_write_inode(dir);
+	if (res)
+		goto out;
+
+	res = hfsplus_cat_write_inode(inode);
+	goto out;
+
+out_err:
+	clear_nlink(inode);
+	hfsplus_delete_inode(inode);
+	iput(inode);
+out:
+	mutex_unlock(&sbi->vh_mutex);
+	return res;
+}
+
+static int hfsplus_mknod(struct mnt_idmap *idmap, struct inode *dir,
+			 struct dentry *dentry, umode_t mode, dev_t rdev)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
+	struct inode *inode;
+	int res = -ENOMEM;
+
+	mutex_lock(&sbi->vh_mutex);
+	inode = hfsplus_new_inode(dir->i_sb, dir, mode);
+	if (!inode)
+		goto out;
+
+	hfs_dbg("dir->i_ino %llu, inode->i_ino %llu\n",
+		dir->i_ino, inode->i_ino);
+
+	if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode))
+		init_special_inode(inode, mode, rdev);
+
+	res = hfsplus_create_cat(inode->i_ino, dir, &dentry->d_name, inode);
+	if (res)
+		goto failed_mknod;
+
+	res = hfsplus_init_security(inode, dir, &dentry->d_name);
+	if (res == -EOPNOTSUPP)
+		res = 0; /* Operation is not supported. */
+	else if (res) {
+		/* Try to delete anyway without error analysis. */
+		hfsplus_delete_cat(inode->i_ino, dir, &dentry->d_name);
+		goto failed_mknod;
+	}
+
+	hfsplus_instantiate(dentry, inode, inode->i_ino);
+	mark_inode_dirty(inode);
+
+	res = hfsplus_cat_write_inode(dir);
+	if (res)
+		goto out;
+
+	res = hfsplus_cat_write_inode(inode);
+	goto out;
+
+failed_mknod:
+	clear_nlink(inode);
+	hfsplus_delete_inode(inode);
+	iput(inode);
+out:
+	mutex_unlock(&sbi->vh_mutex);
+	return res;
+}
+
+static int hfsplus_create(struct mnt_idmap *idmap, struct inode *dir,
+			  struct dentry *dentry, umode_t mode)
+{
+	return hfsplus_mknod(&nop_mnt_idmap, dir, dentry, mode, 0);
+}
+
+static struct dentry *hfsplus_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+				    struct dentry *dentry, umode_t mode)
+{
+	return ERR_PTR(hfsplus_mknod(&nop_mnt_idmap, dir, dentry, mode, 0));
+}
+
+static int hfsplus_rename(struct mnt_idmap *idmap,
+			  struct inode *old_dir, struct dentry *old_dentry,
+			  struct inode *new_dir, struct dentry *new_dentry,
+			  unsigned int flags)
+{
+	int res;
+
+	if (flags & ~RENAME_NOREPLACE)
+		return -EINVAL;
+
+	/* Unlink destination if it already exists */
+	if (d_really_is_positive(new_dentry)) {
+		if (d_is_dir(new_dentry))
+			res = hfsplus_rmdir(new_dir, new_dentry);
+		else
+			res = hfsplus_unlink(new_dir, new_dentry);
+		if (res)
+			return res;
+	}
+
+	res = hfsplus_rename_cat((u32)(unsigned long)old_dentry->d_fsdata,
+				 old_dir, &old_dentry->d_name,
+				 new_dir, &new_dentry->d_name);
+	if (!res) {
+		struct inode *inode = d_inode(old_dentry);
+
+		new_dentry->d_fsdata = old_dentry->d_fsdata;
+
+		inode_set_ctime_current(inode);
+		mark_inode_dirty(inode);
+
+		res = hfsplus_cat_write_inode(old_dir);
+		if (res)
+			return res;
+
+		res = hfsplus_cat_write_inode(new_dir);
+		if (res)
+			return res;
+
+		res = hfsplus_cat_write_inode(inode);
+	}
+	return res;
+}
+
+const struct inode_operations hfsplus_dir_inode_operations = {
+	.lookup			= hfsplus_lookup,
+	.create			= hfsplus_create,
+	.link			= hfsplus_link,
+	.unlink			= hfsplus_unlink,
+	.mkdir			= hfsplus_mkdir,
+	.rmdir			= hfsplus_rmdir,
+	.symlink		= hfsplus_symlink,
+	.mknod			= hfsplus_mknod,
+	.rename			= hfsplus_rename,
+	.getattr		= hfsplus_getattr,
+	.listxattr		= hfsplus_listxattr,
+	.fileattr_get		= hfsplus_fileattr_get,
+	.fileattr_set		= hfsplus_fileattr_set,
+};
+
+const struct file_operations hfsplus_dir_operations = {
+	.fsync		= hfsplus_file_fsync,
+	.read		= generic_read_dir,
+	.iterate_shared	= hfsplus_readdir,
+	.unlocked_ioctl = hfsplus_ioctl,
+	.llseek		= generic_file_llseek,
+	.release	= hfsplus_dir_release,
+};