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, 363 insertions, 0 deletions

diff --git a/fs/smb/server/misc.c b/fs/smb/server/misc.c
new file mode 100644
index 000000000..2dd91c9e9
--- /dev/null
+++ b/fs/smb/server/misc.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/kernel.h>
+#include <linux/xattr.h>
+#include <linux/fs.h>
+#include <linux/unicode.h>
+
+#include "misc.h"
+#include "smb_common.h"
+#include "connection.h"
+#include "vfs.h"
+
+#include "mgmt/share_config.h"
+
+/**
+ * match_pattern() - compare a string with a pattern which might include
+ * wildcard '*' and '?'
+ * TODO : implement consideration about DOS_DOT, DOS_QM and DOS_STAR
+ *
+ * @str:	string to compare with a pattern
+ * @len:	string length
+ * @pattern:	pattern string which might include wildcard '*' and '?'
+ *
+ * Return:	0 if pattern matched with the string, otherwise non zero value
+ */
+int match_pattern(const char *str, size_t len, const char *pattern)
+{
+	const char *s = str;
+	const char *p = pattern;
+	bool star = false;
+
+	while (*s && len) {
+		switch (*p) {
+		case '?':
+			s++;
+			len--;
+			p++;
+			break;
+		case '*':
+			star = true;
+			str = s;
+			if (!*++p)
+				return true;
+			pattern = p;
+			break;
+		default:
+			if (tolower(*s) == tolower(*p)) {
+				s++;
+				len--;
+				p++;
+			} else {
+				if (!star)
+					return false;
+				str++;
+				s = str;
+				p = pattern;
+			}
+			break;
+		}
+	}
+
+	if (*p == '*')
+		++p;
+	return !*p;
+}
+
+/*
+ * is_char_allowed() - check for valid character
+ * @ch:		input character to be checked
+ *
+ * Return:	1 if char is allowed, otherwise 0
+ */
+static inline int is_char_allowed(char ch)
+{
+	/* check for control chars, wildcards etc. */
+	if (!(ch & 0x80) &&
+	    (ch <= 0x1f ||
+	     ch == '?' || ch == '"' || ch == '<' ||
+	     ch == '>' || ch == '|' || ch == '*'))
+		return 0;
+
+	return 1;
+}
+
+int ksmbd_validate_filename(char *filename)
+{
+	while (*filename) {
+		char c = *filename;
+
+		filename++;
+		if (!is_char_allowed(c)) {
+			ksmbd_debug(VFS, "File name validation failed: 0x%x\n", c);
+			return -ENOENT;
+		}
+	}
+
+	return 0;
+}
+
+static int ksmbd_validate_stream_name(char *stream_name)
+{
+	while (*stream_name) {
+		char c = *stream_name;
+
+		stream_name++;
+		if (c == '/' || c == ':' || c == '\\') {
+			pr_err("Stream name validation failed: %c\n", c);
+			return -ENOENT;
+		}
+	}
+
+	return 0;
+}
+
+int parse_stream_name(char *filename, char **stream_name, int *s_type)
+{
+	char *stream_type;
+	char *s_name;
+	int rc = 0;
+	bool has_stream_type = false;
+
+	*stream_name = NULL;
+	s_name = filename;
+	filename = strsep(&s_name, ":");
+	ksmbd_debug(SMB, "filename : %s, streams : %s\n", filename, s_name);
+	if (strchr(s_name, ':')) {
+		stream_type = s_name;
+		s_name = strsep(&stream_type, ":");
+
+		rc = ksmbd_validate_stream_name(s_name);
+		if (rc < 0) {
+			rc = -ENOENT;
+			goto out;
+		}
+
+		ksmbd_debug(SMB, "stream name : %s, stream type : %s\n", s_name,
+			    stream_type);
+		if (!strncasecmp("$data", stream_type, 5)) {
+			*s_type = DATA_STREAM;
+			has_stream_type = true;
+		} else if (!strncasecmp("$index_allocation", stream_type, 17)) {
+			*s_type = DIR_STREAM;
+			has_stream_type = true;
+		} else {
+			rc = -ENOENT;
+		}
+	}
+
+	if (has_stream_type && !s_name[0] && *s_type == DATA_STREAM)
+		goto out;
+
+	*stream_name = s_name;
+out:
+	return rc;
+}
+
+/**
+ * convert_to_nt_pathname() - extract and return windows path string
+ *      whose share directory prefix was removed from file path
+ * @share: ksmbd_share_config pointer
+ * @path: path to report
+ *
+ * Return : windows path string or error
+ */
+
+char *convert_to_nt_pathname(struct ksmbd_share_config *share,
+			     const struct path *path)
+{
+	char *pathname, *ab_pathname, *nt_pathname;
+	int share_path_len = share->path_sz;
+	size_t ab_pathname_len;
+	int prefix;
+
+	pathname = kmalloc(PATH_MAX, KSMBD_DEFAULT_GFP);
+	if (!pathname)
+		return ERR_PTR(-EACCES);
+
+	ab_pathname = d_path(path, pathname, PATH_MAX);
+	if (IS_ERR(ab_pathname)) {
+		nt_pathname = ERR_PTR(-EACCES);
+		goto free_pathname;
+	}
+
+	if (strncmp(ab_pathname, share->path, share_path_len)) {
+		nt_pathname = ERR_PTR(-EACCES);
+		goto free_pathname;
+	}
+
+	ab_pathname_len = strlen(&ab_pathname[share_path_len]);
+	prefix = ab_pathname[share_path_len] == '\0' ? 1 : 0;
+	nt_pathname = kmalloc(prefix + ab_pathname_len + 1, KSMBD_DEFAULT_GFP);
+	if (!nt_pathname) {
+		nt_pathname = ERR_PTR(-ENOMEM);
+		goto free_pathname;
+	}
+
+	if (prefix)
+		*nt_pathname = '/';
+	memcpy(nt_pathname + prefix, &ab_pathname[share_path_len],
+	       ab_pathname_len + 1);
+
+	ksmbd_conv_path_to_windows(nt_pathname);
+
+free_pathname:
+	kfree(pathname);
+	return nt_pathname;
+}
+
+int get_nlink(struct kstat *st)
+{
+	int nlink;
+
+	nlink = st->nlink;
+	if (S_ISDIR(st->mode))
+		nlink--;
+
+	return nlink;
+}
+
+void ksmbd_conv_path_to_unix(char *path)
+{
+	strreplace(path, '\\', '/');
+}
+
+void ksmbd_strip_last_slash(char *path)
+{
+	int len = strlen(path);
+
+	while (len && path[len - 1] == '/') {
+		path[len - 1] = '\0';
+		len--;
+	}
+}
+
+void ksmbd_conv_path_to_windows(char *path)
+{
+	strreplace(path, '/', '\\');
+}
+
+char *ksmbd_casefold_sharename(struct unicode_map *um, const char *name)
+{
+	char *cf_name;
+	int cf_len;
+
+	cf_name = kzalloc(KSMBD_REQ_MAX_SHARE_NAME, KSMBD_DEFAULT_GFP);
+	if (!cf_name)
+		return ERR_PTR(-ENOMEM);
+
+	if (IS_ENABLED(CONFIG_UNICODE) && um) {
+		const struct qstr q_name = {.name = name, .len = strlen(name)};
+
+		cf_len = utf8_casefold(um, &q_name, cf_name,
+				       KSMBD_REQ_MAX_SHARE_NAME);
+		if (cf_len < 0)
+			goto out_ascii;
+
+		return cf_name;
+	}
+
+out_ascii:
+	cf_len = strscpy(cf_name, name, KSMBD_REQ_MAX_SHARE_NAME);
+	if (cf_len < 0) {
+		kfree(cf_name);
+		return ERR_PTR(-E2BIG);
+	}
+
+	for (; *cf_name; ++cf_name)
+		*cf_name = isascii(*cf_name) ? tolower(*cf_name) : *cf_name;
+	return cf_name - cf_len;
+}
+
+/**
+ * ksmbd_extract_sharename() - get share name from tree connect request
+ * @um: pointer to a unicode_map structure for character encoding handling
+ * @treename:	buffer containing tree name and share name
+ *
+ * Return:      share name on success, otherwise error
+ */
+char *ksmbd_extract_sharename(struct unicode_map *um, const char *treename)
+{
+	const char *name = treename, *pos = strrchr(name, '\\');
+
+	if (pos)
+		name = (pos + 1);
+
+	/* caller has to free the memory */
+	return ksmbd_casefold_sharename(um, name);
+}
+
+char *ksmbd_convert_dir_info_name(struct ksmbd_dir_info *d_info,
+				  const struct nls_table *local_nls,
+				  int *conv_len)
+{
+	char *conv;
+	int  sz = min(4 * d_info->name_len, PATH_MAX);
+
+	if (!sz)
+		return NULL;
+
+	conv = kmalloc(sz, KSMBD_DEFAULT_GFP);
+	if (!conv)
+		return NULL;
+
+	/* XXX */
+	*conv_len = smbConvertToUTF16((__le16 *)conv, d_info->name,
+				      d_info->name_len, local_nls, 0);
+	*conv_len *= 2;
+
+	/* We allocate buffer twice bigger than needed. */
+	conv[*conv_len] = 0x00;
+	conv[*conv_len + 1] = 0x00;
+	return conv;
+}
+
+/*
+ * Convert the NT UTC (based 1601-01-01, in hundred nanosecond units)
+ * into Unix UTC (based 1970-01-01, in seconds).
+ */
+struct timespec64 ksmbd_NTtimeToUnix(__le64 ntutc)
+{
+	struct timespec64 ts;
+
+	/* Subtract the NTFS time offset, then convert to 1s intervals. */
+	s64 t = le64_to_cpu(ntutc) - NTFS_TIME_OFFSET;
+	u64 abs_t;
+
+	/*
+	 * Unfortunately can not use normal 64 bit division on 32 bit arch, but
+	 * the alternative, do_div, does not work with negative numbers so have
+	 * to special case them
+	 */
+	if (t < 0) {
+		abs_t = -t;
+		ts.tv_nsec = do_div(abs_t, 10000000) * 100;
+		ts.tv_nsec = -ts.tv_nsec;
+		ts.tv_sec = -abs_t;
+	} else {
+		abs_t = t;
+		ts.tv_nsec = do_div(abs_t, 10000000) * 100;
+		ts.tv_sec = abs_t;
+	}
+
+	return ts;
+}
+
+/* Convert the Unix UTC into NT UTC. */
+inline u64 ksmbd_UnixTimeToNT(struct timespec64 t)
+{
+	/* Convert to 100ns intervals and then add the NTFS time offset. */
+	return (u64)t.tv_sec * 10000000 + t.tv_nsec / 100 + NTFS_TIME_OFFSET;
+}
+
+inline long long ksmbd_systime(void)
+{
+	struct timespec64	ts;
+
+	ktime_get_real_ts64(&ts);
+	return ksmbd_UnixTimeToNT(ts);
+}