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, 318 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/serialio.c b/drivers/accessibility/speakup/serialio.c
new file mode 100644
index 000000000..3418ea31d
--- /dev/null
+++ b/drivers/accessibility/speakup/serialio.c
@@ -0,0 +1,318 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+
+#include "spk_types.h"
+#include "speakup.h"
+#include "spk_priv.h"
+#include "serialio.h"
+
+#include <linux/serial_core.h>
+/* WARNING:  Do not change this to <linux/serial.h> without testing that
+ * SERIAL_PORT_DFNS does get defined to the appropriate value.
+ */
+#include <asm/serial.h>
+
+#ifndef SERIAL_PORT_DFNS
+#define SERIAL_PORT_DFNS
+#endif
+
+static void start_serial_interrupt(int irq);
+
+static const struct old_serial_port rs_table[] = {
+	SERIAL_PORT_DFNS
+};
+
+static const struct old_serial_port *serstate;
+static int timeouts;
+
+static int spk_serial_out(struct spk_synth *in_synth, const char ch);
+static void spk_serial_send_xchar(struct spk_synth *in_synth, char ch);
+static void spk_serial_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear);
+static unsigned char spk_serial_in(struct spk_synth *in_synth);
+static unsigned char spk_serial_in_nowait(struct spk_synth *in_synth);
+static void spk_serial_flush_buffer(struct spk_synth *in_synth);
+static int spk_serial_wait_for_xmitr(struct spk_synth *in_synth);
+
+struct spk_io_ops spk_serial_io_ops = {
+	.synth_out = spk_serial_out,
+	.send_xchar = spk_serial_send_xchar,
+	.tiocmset = spk_serial_tiocmset,
+	.synth_in = spk_serial_in,
+	.synth_in_nowait = spk_serial_in_nowait,
+	.flush_buffer = spk_serial_flush_buffer,
+	.wait_for_xmitr = spk_serial_wait_for_xmitr,
+};
+EXPORT_SYMBOL_GPL(spk_serial_io_ops);
+
+const struct old_serial_port *spk_serial_init(int index)
+{
+	int baud = 9600, quot = 0;
+	unsigned int cval = 0;
+	int cflag = CREAD | HUPCL | CLOCAL | B9600 | CS8;
+	const struct old_serial_port *ser;
+	int err;
+
+	if (index >= ARRAY_SIZE(rs_table)) {
+		pr_info("no port info for ttyS%d\n", index);
+		return NULL;
+	}
+	ser = rs_table + index;
+
+	/*	Divisor, byte size and parity */
+	quot = ser->baud_base / baud;
+	cval = cflag & (CSIZE | CSTOPB);
+#if defined(__powerpc__) || defined(__alpha__)
+	cval >>= 8;
+#else /* !__powerpc__ && !__alpha__ */
+	cval >>= 4;
+#endif /* !__powerpc__ && !__alpha__ */
+	if (cflag & PARENB)
+		cval |= UART_LCR_PARITY;
+	if (!(cflag & PARODD))
+		cval |= UART_LCR_EPAR;
+	if (synth_request_region(ser->port, 8)) {
+		/* try to take it back. */
+		pr_info("Ports not available, trying to steal them\n");
+		__release_region(&ioport_resource, ser->port, 8);
+		err = synth_request_region(ser->port, 8);
+		if (err) {
+			pr_warn("Unable to allocate port at %x, errno %i",
+				ser->port, err);
+			return NULL;
+		}
+	}
+
+	/*	Disable UART interrupts, set DTR and RTS high
+	 *	and set speed.
+	 */
+	outb(cval | UART_LCR_DLAB, ser->port + UART_LCR);	/* set DLAB */
+	outb(quot & 0xff, ser->port + UART_DLL);	/* LS of divisor */
+	outb(quot >> 8, ser->port + UART_DLM);		/* MS of divisor */
+	outb(cval, ser->port + UART_LCR);		/* reset DLAB */
+
+	/* Turn off Interrupts */
+	outb(0, ser->port + UART_IER);
+	outb(UART_MCR_DTR | UART_MCR_RTS, ser->port + UART_MCR);
+
+	/* If we read 0xff from the LSR, there is no UART here. */
+	if (inb(ser->port + UART_LSR) == 0xff) {
+		synth_release_region(ser->port, 8);
+		serstate = NULL;
+		return NULL;
+	}
+
+	mdelay(1);
+	speakup_info.port_tts = ser->port;
+	serstate = ser;
+
+	start_serial_interrupt(ser->irq);
+
+	return ser;
+}
+
+static irqreturn_t synth_readbuf_handler(int irq, void *dev_id)
+{
+	unsigned long flags;
+	int c;
+
+	spin_lock_irqsave(&speakup_info.spinlock, flags);
+	while (inb_p(speakup_info.port_tts + UART_LSR) & UART_LSR_DR) {
+		c = inb_p(speakup_info.port_tts + UART_RX);
+		synth->read_buff_add((u_char)c);
+	}
+	spin_unlock_irqrestore(&speakup_info.spinlock, flags);
+	return IRQ_HANDLED;
+}
+
+static void start_serial_interrupt(int irq)
+{
+	int rv;
+
+	if (!synth->read_buff_add)
+		return;
+
+	rv = request_irq(irq, synth_readbuf_handler, IRQF_SHARED,
+			 "serial", (void *)synth_readbuf_handler);
+
+	if (rv)
+		pr_err("Unable to request Speakup serial I R Q\n");
+	/* Set MCR */
+	outb(UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2,
+	     speakup_info.port_tts + UART_MCR);
+	/* Turn on Interrupts */
+	outb(UART_IER_MSI | UART_IER_RLSI | UART_IER_RDI,
+	     speakup_info.port_tts + UART_IER);
+	inb(speakup_info.port_tts + UART_LSR);
+	inb(speakup_info.port_tts + UART_RX);
+	inb(speakup_info.port_tts + UART_IIR);
+	inb(speakup_info.port_tts + UART_MSR);
+	outb(1, speakup_info.port_tts + UART_FCR);	/* Turn FIFO On */
+}
+
+static void spk_serial_send_xchar(struct spk_synth *synth, char ch)
+{
+	int timeout = SPK_XMITR_TIMEOUT;
+
+	while (spk_serial_tx_busy()) {
+		if (!--timeout)
+			break;
+		udelay(1);
+	}
+	outb(ch, speakup_info.port_tts);
+}
+
+static void spk_serial_tiocmset(struct spk_synth *in_synth, unsigned int set, unsigned int clear)
+{
+	int old = inb(speakup_info.port_tts + UART_MCR);
+
+	outb((old & ~clear) | set, speakup_info.port_tts + UART_MCR);
+}
+
+int spk_serial_synth_probe(struct spk_synth *synth)
+{
+	const struct old_serial_port *ser;
+	int failed = 0;
+
+	if ((synth->ser >= SPK_LO_TTY) && (synth->ser <= SPK_HI_TTY)) {
+		ser = spk_serial_init(synth->ser);
+		if (!ser) {
+			failed = -1;
+		} else {
+			outb_p(0, ser->port);
+			mdelay(1);
+			outb_p('\r', ser->port);
+		}
+	} else {
+		failed = -1;
+		pr_warn("ttyS%i is an invalid port\n", synth->ser);
+	}
+	if (failed) {
+		pr_info("%s: not found\n", synth->long_name);
+		return -ENODEV;
+	}
+	pr_info("%s: ttyS%i, Driver Version %s\n",
+		synth->long_name, synth->ser, synth->version);
+	synth->alive = 1;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spk_serial_synth_probe);
+
+void spk_stop_serial_interrupt(void)
+{
+	if (speakup_info.port_tts == 0)
+		return;
+
+	if (!synth->read_buff_add)
+		return;
+
+	/* Turn off interrupts */
+	outb(0, speakup_info.port_tts + UART_IER);
+	/* Free IRQ */
+	free_irq(serstate->irq, (void *)synth_readbuf_handler);
+}
+EXPORT_SYMBOL_GPL(spk_stop_serial_interrupt);
+
+static int spk_serial_wait_for_xmitr(struct spk_synth *in_synth)
+{
+	int tmout = SPK_XMITR_TIMEOUT;
+
+	if ((in_synth->alive) && (timeouts >= NUM_DISABLE_TIMEOUTS)) {
+		pr_warn("%s: too many timeouts, deactivating speakup\n",
+			in_synth->long_name);
+		in_synth->alive = 0;
+		/* No synth any more, so nobody will restart TTYs, and we thus
+		 * need to do it ourselves.  Now that there is no synth we can
+		 * let application flood anyway
+		 */
+		speakup_start_ttys();
+		timeouts = 0;
+		return 0;
+	}
+	while (spk_serial_tx_busy()) {
+		if (--tmout == 0) {
+			pr_warn("%s: timed out (tx busy)\n",
+				in_synth->long_name);
+			timeouts++;
+			return 0;
+		}
+		udelay(1);
+	}
+	tmout = SPK_CTS_TIMEOUT;
+	while (!((inb_p(speakup_info.port_tts + UART_MSR)) & UART_MSR_CTS)) {
+		/* CTS */
+		if (--tmout == 0) {
+			timeouts++;
+			return 0;
+		}
+		udelay(1);
+	}
+	timeouts = 0;
+	return 1;
+}
+
+static unsigned char spk_serial_in(struct spk_synth *in_synth)
+{
+	int tmout = SPK_SERIAL_TIMEOUT;
+
+	while (!(inb_p(speakup_info.port_tts + UART_LSR) & UART_LSR_DR)) {
+		if (--tmout == 0) {
+			pr_warn("time out while waiting for input.\n");
+			return 0xff;
+		}
+		udelay(1);
+	}
+	return inb_p(speakup_info.port_tts + UART_RX);
+}
+
+static unsigned char spk_serial_in_nowait(struct spk_synth *in_synth)
+{
+	unsigned char lsr;
+
+	lsr = inb_p(speakup_info.port_tts + UART_LSR);
+	if (!(lsr & UART_LSR_DR))
+		return 0;
+	return inb_p(speakup_info.port_tts + UART_RX);
+}
+
+static void spk_serial_flush_buffer(struct spk_synth *in_synth)
+{
+	/* TODO: flush the UART 16550 buffer */
+}
+
+static int spk_serial_out(struct spk_synth *in_synth, const char ch)
+{
+	if (in_synth->alive && spk_serial_wait_for_xmitr(in_synth)) {
+		outb_p(ch, speakup_info.port_tts);
+		return 1;
+	}
+	return 0;
+}
+
+const char *spk_serial_synth_immediate(struct spk_synth *synth,
+				       const char *buff)
+{
+	u_char ch;
+
+	while ((ch = *buff)) {
+		if (ch == '\n')
+			ch = synth->procspeech;
+		if (spk_serial_wait_for_xmitr(synth))
+			outb(ch, speakup_info.port_tts);
+		else
+			return buff;
+		buff++;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(spk_serial_synth_immediate);
+
+void spk_serial_release(struct spk_synth *synth)
+{
+	spk_stop_serial_interrupt();
+	if (speakup_info.port_tts == 0)
+		return;
+	synth_release_region(speakup_info.port_tts, 8);
+	speakup_info.port_tts = 0;
+}
+EXPORT_SYMBOL_GPL(spk_serial_release);