ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 338 insertions, 0 deletions

diff --git a/lib/ts_fsm.c b/lib/ts_fsm.c
new file mode 100644
index 000000000..053615f4f
--- /dev/null
+++ b/lib/ts_fsm.c
@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lib/ts_fsm.c	   A naive finite state machine text search approach
+ *
+ * Authors:	Thomas Graf <tgraf@suug.ch>
+ *
+ * ==========================================================================
+ *
+ *   A finite state machine consists of n states (struct ts_fsm_token)
+ *   representing the pattern as a finite automaton. The data is read
+ *   sequentially on an octet basis. Every state token specifies the number
+ *   of recurrences and the type of value accepted which can be either a
+ *   specific character or ctype based set of characters. The available
+ *   type of recurrences include 1, (0|1), [0 n], and [1 n].
+ *
+ *   The algorithm differs between strict/non-strict mode specifying
+ *   whether the pattern has to start at the first octet. Strict mode
+ *   is enabled by default and can be disabled by inserting
+ *   TS_FSM_HEAD_IGNORE as the first token in the chain.
+ *
+ *   The runtime performance of the algorithm should be around O(n),
+ *   however while in strict mode the average runtime can be better.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/textsearch.h>
+#include <linux/textsearch_fsm.h>
+
+struct ts_fsm
+{
+	unsigned int		ntokens;
+	struct ts_fsm_token	tokens[];
+};
+
+/* other values derived from ctype.h */
+#define _A		0x100 /* ascii */
+#define _W		0x200 /* wildcard */
+
+/* Map to _ctype flags and some magic numbers */
+static const u16 token_map[TS_FSM_TYPE_MAX+1] = {
+	[TS_FSM_SPECIFIC] = 0,
+	[TS_FSM_WILDCARD] = _W,
+	[TS_FSM_CNTRL]	  = _C,
+	[TS_FSM_LOWER]	  = _L,
+	[TS_FSM_UPPER]	  = _U,
+	[TS_FSM_PUNCT]	  = _P,
+	[TS_FSM_SPACE]	  = _S,
+	[TS_FSM_DIGIT]	  = _D,
+	[TS_FSM_XDIGIT]	  = _D | _X,
+	[TS_FSM_ALPHA]	  = _U | _L,
+	[TS_FSM_ALNUM]	  = _U | _L | _D,
+	[TS_FSM_PRINT]	  = _P | _U | _L | _D | _SP,
+	[TS_FSM_GRAPH]	  = _P | _U | _L | _D,
+	[TS_FSM_ASCII]	  = _A,
+};
+
+static const u16 token_lookup_tbl[256] = {
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*   0-  3 */
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*   4-  7 */
+_W|_A|_C,      _W|_A|_C|_S,  _W|_A|_C|_S,  _W|_A|_C|_S,		/*   8- 11 */
+_W|_A|_C|_S,   _W|_A|_C|_S,  _W|_A|_C,     _W|_A|_C,		/*  12- 15 */
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*  16- 19 */
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*  20- 23 */
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*  24- 27 */
+_W|_A|_C,      _W|_A|_C,     _W|_A|_C,     _W|_A|_C,		/*  28- 31 */
+_W|_A|_S|_SP,  _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  32- 35 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  36- 39 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  40- 43 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  44- 47 */
+_W|_A|_D,      _W|_A|_D,     _W|_A|_D,     _W|_A|_D,		/*  48- 51 */
+_W|_A|_D,      _W|_A|_D,     _W|_A|_D,     _W|_A|_D,		/*  52- 55 */
+_W|_A|_D,      _W|_A|_D,     _W|_A|_P,     _W|_A|_P,		/*  56- 59 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  60- 63 */
+_W|_A|_P,      _W|_A|_U|_X,  _W|_A|_U|_X,  _W|_A|_U|_X,		/*  64- 67 */
+_W|_A|_U|_X,   _W|_A|_U|_X,  _W|_A|_U|_X,  _W|_A|_U,		/*  68- 71 */
+_W|_A|_U,      _W|_A|_U,     _W|_A|_U,     _W|_A|_U,		/*  72- 75 */
+_W|_A|_U,      _W|_A|_U,     _W|_A|_U,     _W|_A|_U,		/*  76- 79 */
+_W|_A|_U,      _W|_A|_U,     _W|_A|_U,     _W|_A|_U,		/*  80- 83 */
+_W|_A|_U,      _W|_A|_U,     _W|_A|_U,     _W|_A|_U,		/*  84- 87 */
+_W|_A|_U,      _W|_A|_U,     _W|_A|_U,     _W|_A|_P,		/*  88- 91 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_P,		/*  92- 95 */
+_W|_A|_P,      _W|_A|_L|_X,  _W|_A|_L|_X,  _W|_A|_L|_X,		/*  96- 99 */
+_W|_A|_L|_X,   _W|_A|_L|_X,  _W|_A|_L|_X,  _W|_A|_L,		/* 100-103 */
+_W|_A|_L,      _W|_A|_L,     _W|_A|_L,     _W|_A|_L,		/* 104-107 */
+_W|_A|_L,      _W|_A|_L,     _W|_A|_L,     _W|_A|_L,		/* 108-111 */
+_W|_A|_L,      _W|_A|_L,     _W|_A|_L,     _W|_A|_L,		/* 112-115 */
+_W|_A|_L,      _W|_A|_L,     _W|_A|_L,     _W|_A|_L,		/* 116-119 */
+_W|_A|_L,      _W|_A|_L,     _W|_A|_L,     _W|_A|_P,		/* 120-123 */
+_W|_A|_P,      _W|_A|_P,     _W|_A|_P,     _W|_A|_C,		/* 124-127 */
+_W,            _W,           _W,           _W,			/* 128-131 */
+_W,            _W,           _W,           _W,			/* 132-135 */
+_W,            _W,           _W,           _W,			/* 136-139 */
+_W,            _W,           _W,           _W,			/* 140-143 */
+_W,            _W,           _W,           _W,			/* 144-147 */
+_W,            _W,           _W,           _W,			/* 148-151 */
+_W,            _W,           _W,           _W,			/* 152-155 */
+_W,            _W,           _W,           _W,			/* 156-159 */
+_W|_S|_SP,     _W|_P,        _W|_P,        _W|_P,		/* 160-163 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 164-167 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 168-171 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 172-175 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 176-179 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 180-183 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 184-187 */
+_W|_P,         _W|_P,        _W|_P,        _W|_P,		/* 188-191 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 192-195 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 196-199 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 200-203 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 204-207 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 208-211 */
+_W|_U,         _W|_U,        _W|_U,        _W|_P,		/* 212-215 */
+_W|_U,         _W|_U,        _W|_U,        _W|_U,		/* 216-219 */
+_W|_U,         _W|_U,        _W|_U,        _W|_L,		/* 220-223 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 224-227 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 228-231 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 232-235 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 236-239 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 240-243 */
+_W|_L,         _W|_L,        _W|_L,        _W|_P,		/* 244-247 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L,		/* 248-251 */
+_W|_L,         _W|_L,        _W|_L,        _W|_L};		/* 252-255 */
+
+static inline int match_token(struct ts_fsm_token *t, u8 d)
+{
+	if (t->type)
+		return (token_lookup_tbl[d] & t->type) != 0;
+	else
+		return t->value == d;
+}
+
+static unsigned int fsm_find(struct ts_config *conf, struct ts_state *state)
+{
+	struct ts_fsm *fsm = ts_config_priv(conf);
+	struct ts_fsm_token *cur = NULL, *next;
+	unsigned int match_start, block_idx = 0, tok_idx;
+	unsigned block_len = 0, strict, consumed = state->offset;
+	const u8 *data;
+
+#define GET_NEXT_BLOCK()		\
+({	consumed += block_idx;		\
+	block_idx = 0;			\
+	block_len = conf->get_next_block(consumed, &data, conf, state); })
+
+#define TOKEN_MISMATCH()		\
+	do {				\
+		if (strict)		\
+			goto no_match;	\
+		block_idx++;		\
+		goto startover;		\
+	} while(0)
+
+#define end_of_data() unlikely(block_idx >= block_len && !GET_NEXT_BLOCK())
+
+	if (end_of_data())
+		goto no_match;
+
+	strict = fsm->tokens[0].recur != TS_FSM_HEAD_IGNORE;
+
+startover:
+	match_start = consumed + block_idx;
+
+	for (tok_idx = 0; tok_idx < fsm->ntokens; tok_idx++) {
+		cur = &fsm->tokens[tok_idx];
+
+		if (likely(tok_idx < (fsm->ntokens - 1)))
+			next = &fsm->tokens[tok_idx + 1];
+		else
+			next = NULL;
+
+		switch (cur->recur) {
+		case TS_FSM_SINGLE:
+			if (end_of_data())
+				goto no_match;
+
+			if (!match_token(cur, data[block_idx]))
+				TOKEN_MISMATCH();
+			break;
+
+		case TS_FSM_PERHAPS:
+			if (end_of_data() ||
+			    !match_token(cur, data[block_idx]))
+				continue;
+			break;
+
+		case TS_FSM_MULTI:
+			if (end_of_data())
+				goto no_match;
+
+			if (!match_token(cur, data[block_idx]))
+				TOKEN_MISMATCH();
+
+			block_idx++;
+			fallthrough;
+
+		case TS_FSM_ANY:
+			if (next == NULL)
+				goto found_match;
+
+			if (end_of_data())
+				continue;
+
+			while (!match_token(next, data[block_idx])) {
+				if (!match_token(cur, data[block_idx]))
+					TOKEN_MISMATCH();
+				block_idx++;
+				if (end_of_data())
+					goto no_match;
+			}
+			continue;
+
+		/*
+		 * Optimization: Prefer small local loop over jumping
+		 * back and forth until garbage at head is munched.
+		 */
+		case TS_FSM_HEAD_IGNORE:
+			if (end_of_data())
+				continue;
+
+			while (!match_token(next, data[block_idx])) {
+				/*
+				 * Special case, don't start over upon
+				 * a mismatch, give the user the
+				 * chance to specify the type of data
+				 * allowed to be ignored.
+				 */
+				if (!match_token(cur, data[block_idx]))
+					goto no_match;
+
+				block_idx++;
+				if (end_of_data())
+					goto no_match;
+			}
+
+			match_start = consumed + block_idx;
+			continue;
+		}
+
+		block_idx++;
+	}
+
+	if (end_of_data())
+		goto found_match;
+
+no_match:
+	return UINT_MAX;
+
+found_match:
+	state->offset = consumed + block_idx;
+	return match_start;
+}
+
+static struct ts_config *fsm_init(const void *pattern, unsigned int len,
+				    gfp_t gfp_mask, int flags)
+{
+	int i, err = -EINVAL;
+	struct ts_config *conf;
+	struct ts_fsm *fsm;
+	struct ts_fsm_token *tokens = (struct ts_fsm_token *) pattern;
+	unsigned int ntokens = len / sizeof(*tokens);
+	size_t priv_size = sizeof(*fsm) + len;
+
+	if (len  % sizeof(struct ts_fsm_token) || ntokens < 1)
+		goto errout;
+
+	if (flags & TS_IGNORECASE)
+		goto errout;
+
+	for (i = 0; i < ntokens; i++) {
+		struct ts_fsm_token *t = &tokens[i];
+
+		if (t->type > TS_FSM_TYPE_MAX || t->recur > TS_FSM_RECUR_MAX)
+			goto errout;
+
+		if (t->recur == TS_FSM_HEAD_IGNORE &&
+		    (i != 0 || i == (ntokens - 1)))
+			goto errout;
+	}
+
+	conf = alloc_ts_config(priv_size, gfp_mask);
+	if (IS_ERR(conf))
+		return conf;
+
+	conf->flags = flags;
+	fsm = ts_config_priv(conf);
+	fsm->ntokens = ntokens;
+	memcpy(fsm->tokens, pattern, len);
+
+	for (i = 0; i < fsm->ntokens; i++) {
+		struct ts_fsm_token *t = &fsm->tokens[i];
+		t->type = token_map[t->type];
+	}
+
+	return conf;
+
+errout:
+	return ERR_PTR(err);
+}
+
+static void *fsm_get_pattern(struct ts_config *conf)
+{
+	struct ts_fsm *fsm = ts_config_priv(conf);
+	return fsm->tokens;
+}
+
+static unsigned int fsm_get_pattern_len(struct ts_config *conf)
+{
+	struct ts_fsm *fsm = ts_config_priv(conf);
+	return fsm->ntokens * sizeof(struct ts_fsm_token);
+}
+
+static struct ts_ops fsm_ops = {
+	.name		  = "fsm",
+	.find		  = fsm_find,
+	.init		  = fsm_init,
+	.get_pattern	  = fsm_get_pattern,
+	.get_pattern_len  = fsm_get_pattern_len,
+	.owner		  = THIS_MODULE,
+	.list		  = LIST_HEAD_INIT(fsm_ops.list)
+};
+
+static int __init init_fsm(void)
+{
+	return textsearch_register(&fsm_ops);
+}
+
+static void __exit exit_fsm(void)
+{
+	textsearch_unregister(&fsm_ops);
+}
+
+MODULE_DESCRIPTION("naive finite state machine text search");
+MODULE_LICENSE("GPL");
+
+module_init(init_fsm);
+module_exit(exit_fsm);