KGDB/KDB FIQ (NMI) debugger

index c4d2fc1..7800cce 100644
@@ -240,6 +240,7 @@ extern void kgdb_arch_late(void);
  * hardware breakpoints.
  * @correct_hw_break: Allow an architecture to specify how to correct the
  * hardware debug registers.
+ * @enable_nmi: Manage NMI-triggered entry to KGDB
  */
 struct kgdb_arch {
 	unsigned char		gdb_bpt_instr[BREAK_INSTR_SIZE];

@@ -252,6 +253,8 @@ struct kgdb_arch {
 	void	(*disable_hw_break)(struct pt_regs *regs);
 	void	(*remove_all_hw_break)(void);
 	void	(*correct_hw_break)(void);
+
+	void	(*enable_nmi)(bool on);
 };
 
 /**

index 0557f24..17e073c 100644
@@ -672,6 +672,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 {
 	struct kgdb_state kgdb_var;
 	struct kgdb_state *ks = &kgdb_var;
+	int ret = 0;
+
+	if (arch_kgdb_ops.enable_nmi)
+		arch_kgdb_ops.enable_nmi(0);
 
 	ks->cpu			= raw_smp_processor_id();
 	ks->ex_vector		= evector;

@@ -681,11 +685,15 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	ks->linux_regs		= regs;
 
 	if (kgdb_reenter_check(ks))
-		return 0; /* Ouch, double exception ! */
+		goto out; /* Ouch, double exception ! */
 	if (kgdb_info[ks->cpu].enter_kgdb != 0)
-		return 0;
+		goto out;
 
-	return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+	ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+out:
+	if (arch_kgdb_ops.enable_nmi)
+		arch_kgdb_ops.enable_nmi(1);
+	return ret;
 }
 
 int kgdb_nmicallback(int cpu, void *regs)

index 31df170..1261dc7 100644
@@ -21,6 +21,7 @@
 #include <linux/smp.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
+#include <linux/atomic.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/init.h>

@@ -2107,6 +2108,32 @@ static int kdb_dmesg(int argc, const char **argv)
 	return 0;
 }
 #endif /* CONFIG_PRINTK */
+
+/* Make sure we balance enable/disable calls, must disable first. */
+static atomic_t kdb_nmi_disabled;
+
+static int kdb_disable_nmi(int argc, const char *argv[])
+{
+	if (atomic_read(&kdb_nmi_disabled))
+		return 0;
+	atomic_set(&kdb_nmi_disabled, 1);
+	arch_kgdb_ops.enable_nmi(0);
+	return 0;
+}
+
+static int kdb_param_enable_nmi(const char *val, const struct kernel_param *kp)
+{
+	if (!atomic_add_unless(&kdb_nmi_disabled, -1, 0))
+		return -EINVAL;
+	arch_kgdb_ops.enable_nmi(1);
+	return 0;
+}
+
+static const struct kernel_param_ops kdb_param_ops_enable_nmi = {
+	.set = kdb_param_enable_nmi,
+};
+module_param_cb(enable_nmi, &kdb_param_ops_enable_nmi, NULL, 0600);
+
 /*
  * kdb_cpu - This function implements the 'cpu' command.
  *	cpu	[<cpunum>]

@@ -2851,6 +2878,10 @@ static void __init kdb_inittab(void)
 	kdb_register_repeat("dmesg", kdb_dmesg, "[lines]",
 	  "Display syslog buffer", 0, KDB_REPEAT_NONE);
 #endif
+	if (arch_kgdb_ops.enable_nmi) {
+		kdb_register_repeat("disable_nmi", kdb_disable_nmi, "",
+		  "Disable NMI entry to KDB", 0, KDB_REPEAT_NONE);
+	}
 	kdb_register_repeat("defcmd", kdb_defcmd, "name \"usage\" \"help\"",
 	  "Define a set of commands, down to endefcmd", 0, KDB_REPEAT_NONE);
 	kdb_register_repeat("kill", kdb_kill, "<-signal> <pid>",

index 42d9e86..7f6fe6e 100644
@@ -13,6 +13,14 @@
  * Copyright (C) 2009 Jason Wessel <[email protected]>
  */
 
+typedef enum {
+	KDB_REPEAT_NONE = 0,	/* Do not repeat this command */
+	KDB_REPEAT_NO_ARGS,	/* Repeat the command without arguments */
+	KDB_REPEAT_WITH_ARGS,	/* Repeat the command including its arguments */
+} kdb_repeat_t;
+
+typedef int (*kdb_func_t)(int, const char **);
+
 #ifdef	CONFIG_KGDB_KDB
 #include <linux/init.h>
 #include <linux/sched.h>

@@ -32,14 +40,6 @@ extern atomic_t kdb_event;
 
 #define KDB_MAXARGS    16 /* Maximum number of arguments to a function  */
 
-typedef enum {
-	KDB_REPEAT_NONE = 0,	/* Do not repeat this command */
-	KDB_REPEAT_NO_ARGS,	/* Repeat the command without arguments */
-	KDB_REPEAT_WITH_ARGS,	/* Repeat the command including its arguments */
-} kdb_repeat_t;
-
-typedef int (*kdb_func_t)(int, const char **);
-
 /* KDB return codes from a command or internal kdb function */
 #define KDB_NOTFOUND	(-1)
 #define KDB_ARGCOUNT	(-2)

@@ -149,11 +149,14 @@ extern int kdb_register_repeat(char *, kdb_func_t, char *, char *,
 			       short, kdb_repeat_t);
 extern int kdb_unregister(char *);
 #else /* ! CONFIG_KGDB_KDB */
-#define kdb_printf(...)
-#define kdb_init(x)
-#define kdb_register(...)
-#define kdb_register_repeat(...)
-#define kdb_uregister(x)
+static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
+static inline void kdb_init(int level) {}
+static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
+			       char *help, short minlen) { return 0; }
+static inline int kdb_register_repeat(char *cmd, kdb_func_t func, char *usage,
+				      char *help, short minlen,
+				      kdb_repeat_t repeat) { return 0; }
+static inline int kdb_unregister(char *cmd) { return 0; }
 #endif	/* CONFIG_KGDB_KDB */
 enum {
 	KDB_NOT_INITIALIZED,

index 046279c..dcb2d5a 100644
@@ -2129,6 +2129,7 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
 	int bits = 8;
 	int parity = 'n';
 	int flow = 'n';
+	int ret;
 
 	if (!state || !state->uart_port)
 		return -1;

@@ -2137,6 +2138,22 @@ static int uart_poll_init(struct tty_driver *driver, int line, char *options)
 	if (!(port->ops->poll_get_char && port->ops->poll_put_char))
 		return -1;
 
+	if (port->ops->poll_init) {
+		struct tty_port *tport = &state->port;
+
+		ret = 0;
+		mutex_lock(&tport->mutex);
+		/*
+		 * We don't set ASYNCB_INITIALIZED as we only initialized the
+		 * hw, e.g. state->xmit is still uninitialized.
+		 */
+		if (!test_bit(ASYNCB_INITIALIZED, &tport->flags))
+			ret = port->ops->poll_init(port);
+		mutex_unlock(&tport->mutex);
+		if (ret)
+			return ret;
+	}
+
 	if (options) {
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 		return uart_set_options(port, NULL, baud, parity, bits, flow);

index 7cf0b68..822c887 100644
@@ -274,6 +274,7 @@ struct uart_ops {
 	int		(*verify_port)(struct uart_port *, struct serial_struct *);
 	int		(*ioctl)(struct uart_port *, unsigned int, unsigned long);
 #ifdef CONFIG_CONSOLE_POLL
+	int		(*poll_init)(struct uart_port *);
 	void	(*poll_put_char)(struct uart_port *, unsigned char);
 	int		(*poll_get_char)(struct uart_port *);
 #endif

index cede938..45137e4 100644
@@ -1309,10 +1309,9 @@ static void pl011_put_poll_char(struct uart_port *port,
 
 #endif /* CONFIG_CONSOLE_POLL */
 
-static int pl011_startup(struct uart_port *port)
+static int pl011_hwinit(struct uart_port *port)
 {
 	struct uart_amba_port *uap = (struct uart_amba_port *)port;
-	unsigned int cr;
 	int retval;
 
 	/* Optionaly enable pins to be muxed in and configured */

@@ -1337,6 +1336,37 @@ static int pl011_startup(struct uart_port *port)
 	       UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
 
 	/*
+	 * Save interrupts enable mask, and enable RX interrupts in case if
+	 * the interrupt is used for NMI entry.
+	 */
+	uap->im = readw(uap->port.membase + UART011_IMSC);
+	writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
+
+	if (uap->port.dev->platform_data) {
+		struct amba_pl011_data *plat;
+
+		plat = uap->port.dev->platform_data;
+		if (plat->init)
+			plat->init();
+	}
+	return 0;
+ out:
+	return retval;
+}
+
+static int pl011_startup(struct uart_port *port)
+{
+	struct uart_amba_port *uap = (struct uart_amba_port *)port;
+	unsigned int cr;
+	int retval;
+
+	retval = pl011_hwinit(port);
+	if (retval)
+		goto clk_dis;
+
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	/*
 	 * Allocate the IRQ
 	 */
 	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);

@@ -1395,19 +1425,10 @@ static int pl011_startup(struct uart_port *port)
 	writew(uap->im, uap->port.membase + UART011_IMSC);
 	spin_unlock_irq(&uap->port.lock);
 
-	if (uap->port.dev->platform_data) {
-		struct amba_pl011_data *plat;
-
-		plat = uap->port.dev->platform_data;
-		if (plat->init)
-			plat->init();
-	}
-
 	return 0;
 
  clk_dis:
 	clk_disable_unprepare(uap->clk);
- out:
 	return retval;
 }
 

@@ -1688,6 +1709,7 @@ static struct uart_ops amba_pl011_pops = {
 	.config_port	= pl011_config_port,
 	.verify_port	= pl011_verify_port,
 #ifdef CONFIG_CONSOLE_POLL
+	.poll_init     = pl011_hwinit,
 	.poll_get_char = pl011_get_poll_char,
 	.poll_put_char = pl011_put_poll_char,
 #endif

index 45137e4..459f8ba 100644
@@ -1284,11 +1284,40 @@ static void pl011_break_ctl(struct uart_port *port, int break_state)
 }
 
 #ifdef CONFIG_CONSOLE_POLL
+
+static void pl011_quiesce_irqs(struct uart_port *port)
+{
+	struct uart_amba_port *uap = (struct uart_amba_port *)port;
+	unsigned char __iomem *regs = uap->port.membase;
+
+	writew(readw(regs + UART011_MIS), regs + UART011_ICR);
+	/*
+	 * There is no way to clear TXIM as this is "ready to transmit IRQ", so
+	 * we simply mask it. start_tx() will unmask it.
+	 *
+	 * Note we can race with start_tx(), and if the race happens, the
+	 * polling user might get another interrupt just after we clear it.
+	 * But it should be OK and can happen even w/o the race, e.g.
+	 * controller immediately got some new data and raised the IRQ.
+	 *
+	 * And whoever uses polling routines assumes that it manages the device
+	 * (including tx queue), so we're also fine with start_tx()'s caller
+	 * side.
+	 */
+	writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC);
+}
+
 static int pl011_get_poll_char(struct uart_port *port)
 {
 	struct uart_amba_port *uap = (struct uart_amba_port *)port;
 	unsigned int status;
 
+	/*
+	 * The caller might need IRQs lowered, e.g. if used with KDB NMI
+	 * debugger.
+	 */
+	pl011_quiesce_irqs(port);
+
 	status = readw(uap->port.membase + UART01x_FR);
 	if (status & UART01x_FR_RXFE)
 		return NO_POLL_CHAR;

402 lines not on this page · raw message

index 2b42a01..3f63d83 100644
@@ -145,6 +145,8 @@ __setup("kgdboc=", kgdboc_option_setup);
 
 static void cleanup_kgdboc(void)
 {
+	if (kgdb_unregister_nmi_console())
+		return;
 	kgdboc_unregister_kbd();
 	if (configured == 1)
 		kgdb_unregister_io_module(&kgdboc_io_ops);

@@ -198,11 +200,18 @@ do_register:
 	if (err)
 		goto noconfig;
 
+	err = kgdb_register_nmi_console();
+	if (err)
+		goto nmi_con_failed;
+
 	configured = 1;
 
 	return 0;
 
+nmi_con_failed:
+	kgdb_unregister_io_module(&kgdboc_io_ops);
 noconfig:
+	kgdboc_unregister_kbd();
 	config[0] = 0;
 	configured = 0;
 	cleanup_kgdboc();

index 7800cce..4dff0c6 100644
@@ -286,6 +286,16 @@ extern struct kgdb_arch		arch_kgdb_ops;
 
 extern unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs);
 
+#ifdef CONFIG_SERIAL_KGDB_NMI
+extern int kgdb_register_nmi_console(void);
+extern int kgdb_unregister_nmi_console(void);
+extern bool kgdb_nmi_poll_knock(void);
+#else
+static inline int kgdb_register_nmi_console(void) { return 0; }
+static inline int kgdb_unregister_nmi_console(void) { return 0; }
+static inline bool kgdb_nmi_poll_knock(void) { return 1; }
+#endif
+
 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern struct kgdb_io *dbg_io_ops;

@@ -32,10 +32,10 @@
 
 static int kgdb_nmi_knock = 1;
 module_param_named(knock, kgdb_nmi_knock, int, 0600);
-MODULE_PARM_DESC(knock, "if set to 1 (default), the special '$3#33' command "
-			"must be used to enter the debugger; when set to 0, "
-			"hitting return key is enough to enter the debugger; "
-			"when set to -1, the debugger is entered immediately "
+MODULE_PARM_DESC(knock, "if set to 1 (default), the special '$3#33' command " \
+			"must be used to enter the debugger; when set to 0, " \
+			"hitting return key is enough to enter the debugger; " \
+			"when set to -1, the debugger is entered immediately " \
 			"upon NMI");
 
 static char *kgdb_nmi_magic = "$3#33";

402 lines not on this page · raw message

index 2b42a01..3f63d83 100644
@@ -145,6 +145,8 @@ __setup("kgdboc=", kgdboc_option_setup);
 
 static void cleanup_kgdboc(void)
 {
+	if (kgdb_unregister_nmi_console())
+		return;
 	kgdboc_unregister_kbd();
 	if (configured == 1)
 		kgdb_unregister_io_module(&kgdboc_io_ops);

@@ -198,11 +200,18 @@ do_register:
 	if (err)
 		goto noconfig;
 
+	err = kgdb_register_nmi_console();
+	if (err)
+		goto nmi_con_failed;
+
 	configured = 1;
 
 	return 0;
 
+nmi_con_failed:
+	kgdb_unregister_io_module(&kgdboc_io_ops);
 noconfig:
+	kgdboc_unregister_kbd();
 	config[0] = 0;
 	configured = 0;
 	cleanup_kgdboc();

index 7800cce..4dff0c6 100644
@@ -286,6 +286,16 @@ extern struct kgdb_arch		arch_kgdb_ops;
 
 extern unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs);
 
+#ifdef CONFIG_SERIAL_KGDB_NMI
+extern int kgdb_register_nmi_console(void);
+extern int kgdb_unregister_nmi_console(void);
+extern bool kgdb_nmi_poll_knock(void);
+#else
+static inline int kgdb_register_nmi_console(void) { return 0; }
+static inline int kgdb_unregister_nmi_console(void) { return 0; }
+static inline bool kgdb_nmi_poll_knock(void) { return 1; }
+#endif
+
 extern int kgdb_register_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
 extern struct kgdb_io *dbg_io_ops;

index 48066ce..807e547 100644
@@ -11,6 +11,8 @@
 #define __ARM_KGDB_H__
 
 #include <linux/ptrace.h>
+#include <linux/linkage.h>
+#include <asm/exception.h>
 
 /*
  * GDB assumes that we're a user process being debugged, so

@@ -47,6 +49,12 @@ static inline void arch_kgdb_breakpoint(void)
 extern void kgdb_handle_bus_error(void);
 extern int kgdb_fault_expected;
 
+extern char kgdb_fiq_handler;
+extern char kgdb_fiq_handler_end;
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs);
+extern int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq,
+		     void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on),
+		     bool (*mach_is_kgdb_fiq)(unsigned int irq));
 #endif /* !__ASSEMBLY__ */
 
 /*

124 lines not on this page · raw message

index e0d5388..df2fc82 100644
@@ -66,6 +66,34 @@ static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];
 
 static int vic_id;
 
+static void __iomem *vic_base(struct irq_data *d)
+{
+	return (void __iomem *)irq_data_get_irq_chip_data(d);
+}
+
+void vic_fiq_select(unsigned int irq, bool on)
+{
+	void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+	void __iomem *sel = base + VIC_INT_SELECT;
+	u32 msk = 1 << irq;
+	u32 val;
+
+	pr_debug("rerouting VIC vector %d to %s\n", irq, on ? "FIQ" : "IRQ");
+
+	val = readl(sel);
+	val &= ~msk;
+	if (on)
+		val |= msk;
+	writel(val, sel);
+}
+
+bool vic_is_fiq_rised(unsigned int irq)
+{
+	void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+
+	return readl(base + VIC_FIQ_STATUS) & (1 << irq);
+}
+
 /**
  * vic_init2 - common initialisation code
  * @base: Base of the VIC.

index e14af1a..2728975 100644
@@ -52,6 +52,8 @@ void __vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources,
 void vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, u32 resume_sources);
 int vic_of_init(struct device_node *node, struct device_node *parent);
 void vic_handle_irq(struct pt_regs *regs);
+void vic_fiq_select(unsigned int irq, bool on);
+bool vic_is_fiq_rised(unsigned int irq);
 
 #endif /* __ASSEMBLY__ */
 #endif

new file mode 100644
index 0000000..3cdf71d
@@ -0,0 +1,31 @@
+/*
+ * KGDB FIQ board support
+ *
+ * Copyright 2012 Linaro Ltd.
+ *		  Anton Vorontsov <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <asm/hardware/vic.h>
+
+static int kgdb_fiq;
+module_param_named(uart_num, kgdb_fiq, int, 0600);
+MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ");
+
+static int __init kgdb_fiq_init(void)
+{
+	WARN_ON(kgdb_fiq > INT_UARTINT2 - INT_UARTINT0);
+
+	return kgdb_register_fiq(INT_UARTINT0 + kgdb_fiq,
+				 vic_fiq_select,
+				 vic_is_fiq_rised);
+}
+console_initcall(kgdb_fiq_init);