1 files changed, 190 insertions, 76 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 76e506ee335c..66a5e2faf57e 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -20,6 +20,7 @@
 #include <linux/device.h>
 #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
 #include <linux/serial_core.h>
+#include <linux/sysrq.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/security.h>
@@ -40,6 +41,8 @@ static struct lock_class_key port_lock_key;
 
 #define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)
 
+#define SYSRQ_TIMEOUT	(HZ * 5)
+
 static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
 					struct ktermios *old_termios);
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
@@ -1908,6 +1911,24 @@ static int uart_proc_show(struct seq_file *m, void *v)
 }
 #endif
 
+static inline bool uart_console_enabled(struct uart_port *port)
+{
+	return uart_console(port) && (port->cons->flags & CON_ENABLED);
+}
+
+/*
+ * Ensure that the serial console lock is initialised early.
+ * If this port is a console, then the spinlock is already initialised.
+ */
+static inline void uart_port_spin_lock_init(struct uart_port *port)
+{
+	if (uart_console(port))
+		return;
+
+	spin_lock_init(&port->lock);
+	lockdep_set_class(&port->lock, &port_lock_key);
+}
+
 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
 /**
  *	uart_console_write - write a console message to a serial port
@@ -2060,16 +2081,7 @@ uart_set_options(struct uart_port *port, struct console *co,
 	struct ktermios termios;
 	static struct ktermios dummy;
 
-	/*
-	 * Ensure that the serial console lock is initialised
-	 * early.
-	 * If this port is a console, then the spinlock is already
-	 * initialised.
-	 */
-	if (!(uart_console(port) && (port->cons->flags & CON_ENABLED))) {
-		spin_lock_init(&port->lock);
-		lockdep_set_class(&port->lock, &port_lock_key);
-	}
+	uart_port_spin_lock_init(port);
 
 	memset(&termios, 0, sizeof(struct ktermios));
 
@@ -2605,7 +2617,7 @@ struct tty_driver *uart_console_device(struct console *co, int *index)
 }
 EXPORT_SYMBOL_GPL(uart_console_device);
 
-static ssize_t uart_get_attr_uartclk(struct device *dev,
+static ssize_t uartclk_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2615,7 +2627,7 @@ static ssize_t uart_get_attr_uartclk(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.baud_base * 16);
 }
 
-static ssize_t uart_get_attr_type(struct device *dev,
+static ssize_t type_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2624,7 +2636,8 @@ static ssize_t uart_get_attr_type(struct device *dev,
 	uart_get_info(port, &tmp);
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.type);
 }
-static ssize_t uart_get_attr_line(struct device *dev,
+
+static ssize_t line_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2634,7 +2647,7 @@ static ssize_t uart_get_attr_line(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.line);
 }
 
-static ssize_t uart_get_attr_port(struct device *dev,
+static ssize_t port_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2648,7 +2661,7 @@ static ssize_t uart_get_attr_port(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "0x%lX\n", ioaddr);
 }
 
-static ssize_t uart_get_attr_irq(struct device *dev,
+static ssize_t irq_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2658,7 +2671,7 @@ static ssize_t uart_get_attr_irq(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.irq);
 }
 
-static ssize_t uart_get_attr_flags(struct device *dev,
+static ssize_t flags_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2668,7 +2681,7 @@ static ssize_t uart_get_attr_flags(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "0x%X\n", tmp.flags);
 }
 
-static ssize_t uart_get_attr_xmit_fifo_size(struct device *dev,
+static ssize_t xmit_fifo_size_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2678,8 +2691,7 @@ static ssize_t uart_get_attr_xmit_fifo_size(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.xmit_fifo_size);
 }
 
-
-static ssize_t uart_get_attr_close_delay(struct device *dev,
+static ssize_t close_delay_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2689,8 +2701,7 @@ static ssize_t uart_get_attr_close_delay(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.close_delay);
 }
 
-
-static ssize_t uart_get_attr_closing_wait(struct device *dev,
+static ssize_t closing_wait_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2700,7 +2711,7 @@ static ssize_t uart_get_attr_closing_wait(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.closing_wait);
 }
 
-static ssize_t uart_get_attr_custom_divisor(struct device *dev,
+static ssize_t custom_divisor_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2710,7 +2721,7 @@ static ssize_t uart_get_attr_custom_divisor(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.custom_divisor);
 }
 
-static ssize_t uart_get_attr_io_type(struct device *dev,
+static ssize_t io_type_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2720,7 +2731,7 @@ static ssize_t uart_get_attr_io_type(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.io_type);
 }
 
-static ssize_t uart_get_attr_iomem_base(struct device *dev,
+static ssize_t iomem_base_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2730,7 +2741,7 @@ static ssize_t uart_get_attr_iomem_base(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "0x%lX\n", (unsigned long)tmp.iomem_base);
 }
 
-static ssize_t uart_get_attr_iomem_reg_shift(struct device *dev,
+static ssize_t iomem_reg_shift_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct serial_struct tmp;
@@ -2740,40 +2751,92 @@ static ssize_t uart_get_attr_iomem_reg_shift(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.iomem_reg_shift);
 }
 
-static DEVICE_ATTR(type, S_IRUSR | S_IRGRP, uart_get_attr_type, NULL);
-static DEVICE_ATTR(line, S_IRUSR | S_IRGRP, uart_get_attr_line, NULL);
-static DEVICE_ATTR(port, S_IRUSR | S_IRGRP, uart_get_attr_port, NULL);
-static DEVICE_ATTR(irq, S_IRUSR | S_IRGRP, uart_get_attr_irq, NULL);
-static DEVICE_ATTR(flags, S_IRUSR | S_IRGRP, uart_get_attr_flags, NULL);
-static DEVICE_ATTR(xmit_fifo_size, S_IRUSR | S_IRGRP, uart_get_attr_xmit_fifo_size, NULL);
-static DEVICE_ATTR(uartclk, S_IRUSR | S_IRGRP, uart_get_attr_uartclk, NULL);
-static DEVICE_ATTR(close_delay, S_IRUSR | S_IRGRP, uart_get_attr_close_delay, NULL);
-static DEVICE_ATTR(closing_wait, S_IRUSR | S_IRGRP, uart_get_attr_closing_wait, NULL);
-static DEVICE_ATTR(custom_divisor, S_IRUSR | S_IRGRP, uart_get_attr_custom_divisor, NULL);
-static DEVICE_ATTR(io_type, S_IRUSR | S_IRGRP, uart_get_attr_io_type, NULL);
-static DEVICE_ATTR(iomem_base, S_IRUSR | S_IRGRP, uart_get_attr_iomem_base, NULL);
-static DEVICE_ATTR(iomem_reg_shift, S_IRUSR | S_IRGRP, uart_get_attr_iomem_reg_shift, NULL);
+static ssize_t console_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct tty_port *port = dev_get_drvdata(dev);
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport;
+	bool console = false;
+
+	mutex_lock(&port->mutex);
+	uport = uart_port_check(state);
+	if (uport)
+		console = uart_console_enabled(uport);
+	mutex_unlock(&port->mutex);
+
+	return sprintf(buf, "%c\n", console ? 'Y' : 'N');
+}
+
+static ssize_t console_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct tty_port *port = dev_get_drvdata(dev);
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport;
+	bool oldconsole, newconsole;
+	int ret;
+
+	ret = kstrtobool(buf, &newconsole);
+	if (ret)
+		return ret;
+
+	mutex_lock(&port->mutex);
+	uport = uart_port_check(state);
+	if (uport) {
+		oldconsole = uart_console_enabled(uport);
+		if (oldconsole && !newconsole) {
+			ret = unregister_console(uport->cons);
+		} else if (!oldconsole && newconsole) {
+			if (uart_console(uport))
+				register_console(uport->cons);
+			else
+				ret = -ENOENT;
+		}
+	} else {
+		ret = -ENXIO;
+	}
+	mutex_unlock(&port->mutex);
+
+	return ret < 0 ? ret : count;
+}
+
+static DEVICE_ATTR_RO(uartclk);
+static DEVICE_ATTR_RO(type);
+static DEVICE_ATTR_RO(line);
+static DEVICE_ATTR_RO(port);
+static DEVICE_ATTR_RO(irq);
+static DEVICE_ATTR_RO(flags);
+static DEVICE_ATTR_RO(xmit_fifo_size);
+static DEVICE_ATTR_RO(close_delay);
+static DEVICE_ATTR_RO(closing_wait);
+static DEVICE_ATTR_RO(custom_divisor);
+static DEVICE_ATTR_RO(io_type);
+static DEVICE_ATTR_RO(iomem_base);
+static DEVICE_ATTR_RO(iomem_reg_shift);
+static DEVICE_ATTR_RW(console);
 
 static struct attribute *tty_dev_attrs[] = {
+	&dev_attr_uartclk.attr,
 	&dev_attr_type.attr,
 	&dev_attr_line.attr,
 	&dev_attr_port.attr,
 	&dev_attr_irq.attr,
 	&dev_attr_flags.attr,
 	&dev_attr_xmit_fifo_size.attr,
-	&dev_attr_uartclk.attr,
 	&dev_attr_close_delay.attr,
 	&dev_attr_closing_wait.attr,
 	&dev_attr_custom_divisor.attr,
 	&dev_attr_io_type.attr,
 	&dev_attr_iomem_base.attr,
 	&dev_attr_iomem_reg_shift.attr,
-	NULL,
-	};
+	&dev_attr_console.attr,
+	NULL
+};
 
 static const struct attribute_group tty_dev_attr_group = {
 	.attrs = tty_dev_attrs,
-	};
+};
 
 /**
  *	uart_add_one_port - attach a driver-defined port structure
@@ -2824,14 +2887,8 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 		goto out;
 	}
 
-	/*
-	 * If this port is a console, then the spinlock is already
-	 * initialised.
-	 */
-	if (!(uart_console(uport) && (uport->cons->flags & CON_ENABLED))) {
-		spin_lock_init(&uport->lock);
-		lockdep_set_class(&uport->lock, &port_lock_key);
-	}
+	uart_port_spin_lock_init(uport);
+
 	if (uport->cons && uport->dev)
 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
 
@@ -3082,6 +3139,60 @@ void uart_insert_char(struct uart_port *port, unsigned int status,
 }
 EXPORT_SYMBOL_GPL(uart_insert_char);
 
+#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
+static const char sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
+
+static void uart_sysrq_on(struct work_struct *w)
+{
+	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
+
+	sysrq_toggle_support(1);
+	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
+		sysrq_toggle_seq_len, sysrq_toggle_seq);
+}
+static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
+
+/**
+ *	uart_try_toggle_sysrq - Enables SysRq from serial line
+ *	@port: uart_port structure where char(s) after BREAK met
+ *	@ch: new character in the sequence after received BREAK
+ *
+ *	Enables magic SysRq when the required sequence is met on port
+ *	(see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
+ *
+ *	Returns false if @ch is out of enabling sequence and should be
+ *	handled some other way, true if @ch was consumed.
+ */
+static bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
+{
+	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
+
+	if (!sysrq_toggle_seq_len)
+		return false;
+
+	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
+	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
+		port->sysrq_seq = 0;
+		return false;
+	}
+
+	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
+		port->sysrq = jiffies + SYSRQ_TIMEOUT;
+		return true;
+	}
+
+	schedule_work(&sysrq_enable_work);
+
+	port->sysrq = 0;
+	return true;
+}
+#else
+static inline bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
+{
+	return false;
+}
+#endif
+
 int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 {
 	if (!IS_ENABLED(CONFIG_MAGIC_SYSRQ_SERIAL))
@@ -3091,9 +3202,13 @@ int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
 		return 0;
 
 	if (ch && time_before(jiffies, port->sysrq)) {
-		handle_sysrq(ch);
-		port->sysrq = 0;
-		return 1;
+		if (sysrq_mask()) {
+			handle_sysrq(ch);
+			port->sysrq = 0;
+			return 1;
+		}
+		if (uart_try_toggle_sysrq(port, ch))
+			return 1;
 	}
 	port->sysrq = 0;
 
@@ -3110,9 +3225,13 @@ int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
 		return 0;
 
 	if (ch && time_before(jiffies, port->sysrq)) {
-		port->sysrq_ch = ch;
-		port->sysrq = 0;
-		return 1;
+		if (sysrq_mask()) {
+			port->sysrq_ch = ch;
+			port->sysrq = 0;
+			return 1;
+		}
+		if (uart_try_toggle_sysrq(port, ch))
+			return 1;
 	}
 	port->sysrq = 0;
 
@@ -3120,22 +3239,19 @@ int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
 }
 EXPORT_SYMBOL_GPL(uart_prepare_sysrq_char);
 
-void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
+void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long flags)
+__releases(&port->lock)
 {
-	int sysrq_ch;
+	if (port->has_sysrq) {
+		int sysrq_ch = port->sysrq_ch;
 
-	if (!port->has_sysrq) {
-		spin_unlock_irqrestore(&port->lock, irqflags);
-		return;
+		port->sysrq_ch = 0;
+		spin_unlock_irqrestore(&port->lock, flags);
+		if (sysrq_ch)
+			handle_sysrq(sysrq_ch);
+	} else {
+		spin_unlock_irqrestore(&port->lock, flags);
 	}
-
-	sysrq_ch = port->sysrq_ch;
-	port->sysrq_ch = 0;
-
-	spin_unlock_irqrestore(&port->lock, irqflags);
-
-	if (sysrq_ch)
-		handle_sysrq(sysrq_ch);
 }
 EXPORT_SYMBOL_GPL(uart_unlock_and_check_sysrq);
 
@@ -3149,14 +3265,12 @@ int uart_handle_break(struct uart_port *port)
 	if (port->handle_break)
 		port->handle_break(port);
 
-	if (port->has_sysrq) {
-		if (port->cons && port->cons->index == port->line) {
-			if (!port->sysrq) {
-				port->sysrq = jiffies + HZ*5;
-				return 1;
-			}
-			port->sysrq = 0;
+	if (port->has_sysrq && uart_console(port)) {
+		if (!port->sysrq) {
+			port->sysrq = jiffies + SYSRQ_TIMEOUT;
+			return 1;
 		}
+		port->sysrq = 0;
 	}
 
 	if (port->flags & UPF_SAK)