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, 447 insertions, 0 deletions

diff --git a/fs/jffs2/compr_rubin.c b/fs/jffs2/compr_rubin.c
new file mode 100644
index 000000000..9854253d0
--- /dev/null
+++ b/fs/jffs2/compr_rubin.c
@@ -0,0 +1,447 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by Arjan van de Ven <arjanv@redhat.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/jffs2.h>
+#include <linux/errno.h>
+#include "compr.h"
+
+
+#define RUBIN_REG_SIZE   16
+#define UPPER_BIT_RUBIN    (((long) 1)<<(RUBIN_REG_SIZE-1))
+#define LOWER_BITS_RUBIN   ((((long) 1)<<(RUBIN_REG_SIZE-1))-1)
+
+
+#define BIT_DIVIDER_MIPS 1043
+static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241};
+
+struct pushpull {
+	unsigned char *buf;
+	unsigned int buflen;
+	unsigned int ofs;
+	unsigned int reserve;
+};
+
+struct rubin_state {
+	unsigned long p;
+	unsigned long q;
+	unsigned long rec_q;
+	long bit_number;
+	struct pushpull pp;
+	int bit_divider;
+	int bits[8];
+};
+
+static inline void init_pushpull(struct pushpull *pp, char *buf,
+				 unsigned buflen, unsigned ofs,
+				 unsigned reserve)
+{
+	pp->buf = buf;
+	pp->buflen = buflen;
+	pp->ofs = ofs;
+	pp->reserve = reserve;
+}
+
+static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
+{
+	if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve))
+		return -ENOSPC;
+
+	if (bit)
+		pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7)));
+	else
+		pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7)));
+
+	pp->ofs++;
+
+	return 0;
+}
+
+static inline int pushedbits(struct pushpull *pp)
+{
+	return pp->ofs;
+}
+
+static inline int pullbit(struct pushpull *pp)
+{
+	int bit;
+
+	bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;
+
+	pp->ofs++;
+	return bit;
+}
+
+
+static void init_rubin(struct rubin_state *rs, int div, int *bits)
+{
+	int c;
+
+	rs->q = 0;
+	rs->p = (long) (2 * UPPER_BIT_RUBIN);
+	rs->bit_number = (long) 0;
+	rs->bit_divider = div;
+
+	for (c=0; c<8; c++)
+		rs->bits[c] = bits[c];
+}
+
+
+static int encode(struct rubin_state *rs, long A, long B, int symbol)
+{
+
+	long i0, i1;
+	int ret;
+
+	while ((rs->q >= UPPER_BIT_RUBIN) ||
+	       ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) {
+		rs->bit_number++;
+
+		ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0);
+		if (ret)
+			return ret;
+		rs->q &= LOWER_BITS_RUBIN;
+		rs->q <<= 1;
+		rs->p <<= 1;
+	}
+	i0 = A * rs->p / (A + B);
+	if (i0 <= 0)
+		i0 = 1;
+
+	if (i0 >= rs->p)
+		i0 = rs->p - 1;
+
+	i1 = rs->p - i0;
+
+	if (symbol == 0)
+		rs->p = i0;
+	else {
+		rs->p = i1;
+		rs->q += i0;
+	}
+	return 0;
+}
+
+
+static void end_rubin(struct rubin_state *rs)
+{
+
+	int i;
+
+	for (i = 0; i < RUBIN_REG_SIZE; i++) {
+		pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1);
+		rs->q &= LOWER_BITS_RUBIN;
+		rs->q <<= 1;
+	}
+}
+
+
+static void init_decode(struct rubin_state *rs, int div, int *bits)
+{
+	init_rubin(rs, div, bits);
+
+	/* behalve lower */
+	rs->rec_q = 0;
+
+	for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE;
+	     rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp)))
+		;
+}
+
+static void __do_decode(struct rubin_state *rs, unsigned long p,
+			unsigned long q)
+{
+	register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN;
+	unsigned long rec_q;
+	int c, bits = 0;
+
+	/*
+	 * First, work out how many bits we need from the input stream.
+	 * Note that we have already done the initial check on this
+	 * loop prior to calling this function.
+	 */
+	do {
+		bits++;
+		q &= lower_bits_rubin;
+		q <<= 1;
+		p <<= 1;
+	} while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN));
+
+	rs->p = p;
+	rs->q = q;
+
+	rs->bit_number += bits;
+
+	/*
+	 * Now get the bits.  We really want this to be "get n bits".
+	 */
+	rec_q = rs->rec_q;
+	do {
+		c = pullbit(&rs->pp);
+		rec_q &= lower_bits_rubin;
+		rec_q <<= 1;
+		rec_q += c;
+	} while (--bits);
+	rs->rec_q = rec_q;
+}
+
+static int decode(struct rubin_state *rs, long A, long B)
+{
+	unsigned long p = rs->p, q = rs->q;
+	long i0, threshold;
+	int symbol;
+
+	if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN))
+		__do_decode(rs, p, q);
+
+	i0 = A * rs->p / (A + B);
+	if (i0 <= 0)
+		i0 = 1;
+
+	if (i0 >= rs->p)
+		i0 = rs->p - 1;
+
+	threshold = rs->q + i0;
+	symbol = rs->rec_q >= threshold;
+	if (rs->rec_q >= threshold) {
+		rs->q += i0;
+		i0 = rs->p - i0;
+	}
+
+	rs->p = i0;
+
+	return symbol;
+}
+
+
+
+static int out_byte(struct rubin_state *rs, unsigned char byte)
+{
+	int i, ret;
+	struct rubin_state rs_copy;
+	rs_copy = *rs;
+
+	for (i=0; i<8; i++) {
+		ret = encode(rs, rs->bit_divider-rs->bits[i],
+			     rs->bits[i], byte & 1);
+		if (ret) {
+			/* Failed. Restore old state */
+			*rs = rs_copy;
+			return ret;
+		}
+		byte >>= 1 ;
+	}
+	return 0;
+}
+
+static int in_byte(struct rubin_state *rs)
+{
+	int i, result = 0, bit_divider = rs->bit_divider;
+
+	for (i = 0; i < 8; i++)
+		result |= decode(rs, bit_divider - rs->bits[i],
+				 rs->bits[i]) << i;
+
+	return result;
+}
+
+
+
+static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in,
+			     unsigned char *cpage_out, uint32_t *sourcelen,
+			     uint32_t *dstlen)
+	{
+	int outpos = 0;
+	int pos=0;
+	struct rubin_state rs;
+
+	init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32);
+
+	init_rubin(&rs, bit_divider, bits);
+
+	while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos]))
+		pos++;
+
+	end_rubin(&rs);
+
+	/* Tell the caller how much we managed to compress,
+	 * and how much space it took */
+
+	outpos = (pushedbits(&rs.pp)+7)/8;
+
+	if (outpos >= pos)
+		return -1; /* We didn't actually compress */
+	*sourcelen = pos;
+	*dstlen = outpos;
+	return 0;
+}
+#if 0
+/* _compress returns the compressed size, -1 if bigger */
+int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out,
+		   uint32_t *sourcelen, uint32_t *dstlen)
+{
+	return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in,
+				 cpage_out, sourcelen, dstlen);
+}
+#endif
+static int jffs2_dynrubin_compress(unsigned char *data_in,
+				   unsigned char *cpage_out,
+				   uint32_t *sourcelen, uint32_t *dstlen)
+{
+	int bits[8];
+	unsigned char histo[256];
+	int i;
+	int ret;
+	uint32_t mysrclen, mydstlen;
+
+	mysrclen = *sourcelen;
+	mydstlen = *dstlen - 8;
+
+	if (*dstlen <= 12)
+		return -1;
+
+	memset(histo, 0, 256);
+	for (i=0; i<mysrclen; i++)
+		histo[data_in[i]]++;
+	memset(bits, 0, sizeof(int)*8);
+	for (i=0; i<256; i++) {
+		if (i&128)
+			bits[7] += histo[i];
+		if (i&64)
+			bits[6] += histo[i];
+		if (i&32)
+			bits[5] += histo[i];
+		if (i&16)
+			bits[4] += histo[i];
+		if (i&8)
+			bits[3] += histo[i];
+		if (i&4)
+			bits[2] += histo[i];
+		if (i&2)
+			bits[1] += histo[i];
+		if (i&1)
+			bits[0] += histo[i];
+	}
+
+	for (i=0; i<8; i++) {
+		bits[i] = (bits[i] * 256) / mysrclen;
+		if (!bits[i]) bits[i] = 1;
+		if (bits[i] > 255) bits[i] = 255;
+		cpage_out[i] = bits[i];
+	}
+
+	ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen,
+				&mydstlen);
+	if (ret)
+		return ret;
+
+	/* Add back the 8 bytes we took for the probabilities */
+	mydstlen += 8;
+
+	if (mysrclen <= mydstlen) {
+		/* We compressed */
+		return -1;
+	}
+
+	*sourcelen = mysrclen;
+	*dstlen = mydstlen;
+	return 0;
+}
+
+static void rubin_do_decompress(int bit_divider, int *bits,
+				unsigned char *cdata_in, 
+				unsigned char *page_out, uint32_t srclen,
+				uint32_t destlen)
+{
+	int outpos = 0;
+	struct rubin_state rs;
+
+	init_pushpull(&rs.pp, cdata_in, srclen, 0, 0);
+	init_decode(&rs, bit_divider, bits);
+
+	while (outpos < destlen)
+		page_out[outpos++] = in_byte(&rs);
+}
+
+
+static int jffs2_rubinmips_decompress(unsigned char *data_in,
+				      unsigned char *cpage_out,
+				      uint32_t sourcelen, uint32_t dstlen)
+{
+	rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in,
+			    cpage_out, sourcelen, dstlen);
+	return 0;
+}
+
+static int jffs2_dynrubin_decompress(unsigned char *data_in,
+				     unsigned char *cpage_out,
+				     uint32_t sourcelen, uint32_t dstlen)
+{
+	int bits[8];
+	int c;
+
+	for (c=0; c<8; c++)
+		bits[c] = data_in[c];
+
+	rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8,
+			    dstlen);
+	return 0;
+}
+
+static struct jffs2_compressor jffs2_rubinmips_comp = {
+	.priority = JFFS2_RUBINMIPS_PRIORITY,
+	.name = "rubinmips",
+	.compr = JFFS2_COMPR_DYNRUBIN,
+	.compress = NULL, /*&jffs2_rubinmips_compress,*/
+	.decompress = &jffs2_rubinmips_decompress,
+#ifdef JFFS2_RUBINMIPS_DISABLED
+	.disabled = 1,
+#else
+	.disabled = 0,
+#endif
+};
+
+int jffs2_rubinmips_init(void)
+{
+	return jffs2_register_compressor(&jffs2_rubinmips_comp);
+}
+
+void jffs2_rubinmips_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_rubinmips_comp);
+}
+
+static struct jffs2_compressor jffs2_dynrubin_comp = {
+	.priority = JFFS2_DYNRUBIN_PRIORITY,
+	.name = "dynrubin",
+	.compr = JFFS2_COMPR_RUBINMIPS,
+	.compress = jffs2_dynrubin_compress,
+	.decompress = &jffs2_dynrubin_decompress,
+#ifdef JFFS2_DYNRUBIN_DISABLED
+	.disabled = 1,
+#else
+	.disabled = 0,
+#endif
+};
+
+int jffs2_dynrubin_init(void)
+{
+	return jffs2_register_compressor(&jffs2_dynrubin_comp);
+}
+
+void jffs2_dynrubin_exit(void)
+{
+	jffs2_unregister_compressor(&jffs2_dynrubin_comp);
+}