Merge commit 'kgdb/kgdb-next'

arch/x86/kernel/kgdb.c

@@ -85,10 +85,15 @@ void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 	gdb_regs[GDB_DS]	= regs->ds;
 	gdb_regs[GDB_ES]	= regs->es;
 	gdb_regs[GDB_CS]	= regs->cs;
-	gdb_regs[GDB_SS]	= __KERNEL_DS;
 	gdb_regs[GDB_FS]	= 0xFFFF;
 	gdb_regs[GDB_GS]	= 0xFFFF;
-	gdb_regs[GDB_SP]	= (int)&regs->sp;
+	if (user_mode_vm(regs)) {
+		gdb_regs[GDB_SS] = regs->ss;
+		gdb_regs[GDB_SP] = regs->sp;
+	} else {
+		gdb_regs[GDB_SS] = __KERNEL_DS;
+		gdb_regs[GDB_SP] = (unsigned long)&regs->sp;
+	}
 #else
 	gdb_regs[GDB_R8]	= regs->r8;
 	gdb_regs[GDB_R9]	= regs->r9;
@@ -220,8 +225,7 @@ static void kgdb_correct_hw_break(void)
 			dr7 |= ((breakinfo[breakno].len << 2) |
 				 breakinfo[breakno].type) <<
 			       ((breakno << 2) + 16);
-			if (breakno >= 0 && breakno <= 3)
-				set_debugreg(breakinfo[breakno].addr, breakno);
+			set_debugreg(breakinfo[breakno].addr, breakno);
 
 		} else {
 			if ((dr7 & breakbit) && !breakinfo[breakno].enabled) {

include/linux/sched.h

@@ -302,6 +302,7 @@ extern void sched_show_task(struct task_struct *p);
 #ifdef CONFIG_DETECT_SOFTLOCKUP
 extern void softlockup_tick(void);
 extern void touch_softlockup_watchdog(void);
+extern void touch_softlockup_watchdog_sync(void);
 extern void touch_all_softlockup_watchdogs(void);
 extern int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
 				    struct file *filp, void __user *buffer,
@@ -315,6 +316,9 @@ static inline void softlockup_tick(void)
 static inline void touch_softlockup_watchdog(void)
 {
 }
+static inline void touch_softlockup_watchdog_sync(void)
+{
+}
 static inline void touch_all_softlockup_watchdogs(void)
 {
 }

kernel/kgdb.c

@@ -129,6 +129,7 @@ struct task_struct		*kgdb_usethread;
 struct task_struct		*kgdb_contthread;
 
 int				kgdb_single_step;
+pid_t				kgdb_sstep_pid;
 
 /* Our I/O buffers. */
 static char			remcom_in_buffer[BUFMAX];
@@ -541,12 +542,17 @@ static struct task_struct *getthread(struct pt_regs *regs, int tid)
 	 */
 	if (tid == 0 || tid == -1)
 		tid = -atomic_read(&kgdb_active) - 2;
-	if (tid < 0) {
+	if (tid < -1 && tid > -NR_CPUS - 2) {
 		if (kgdb_info[-tid - 2].task)
 			return kgdb_info[-tid - 2].task;
 		else
 			return idle_task(-tid - 2);
 	}
+	if (tid <= 0) {
+		printk(KERN_ERR "KGDB: Internal thread select error\n");
+		dump_stack();
+		return NULL;
+	}
 
 	/*
 	 * find_task_by_pid_ns() does not take the tasklist lock anymore
@@ -590,7 +596,7 @@ static void kgdb_wait(struct pt_regs *regs)
 
 	/* Signal the primary CPU that we are done: */
 	atomic_set(&cpu_in_kgdb[cpu], 0);
-	touch_softlockup_watchdog();
+	touch_softlockup_watchdog_sync();
 	clocksource_touch_watchdog();
 	local_irq_restore(flags);
 }
@@ -1204,8 +1210,10 @@ static int gdb_cmd_exception_pass(struct kgdb_state *ks)
 		return 1;
 
 	} else {
-		error_packet(remcom_out_buffer, -EINVAL);
-		return 0;
+		kgdb_msg_write("KGDB only knows signal 9 (pass)"
+			" and 15 (pass and disconnect)\n"
+			"Executing a continue without signal passing\n", 0);
+		remcom_in_buffer[0] = 'c';
 	}
 
 	/* Indicate fall through */
@@ -1430,10 +1438,10 @@ acquirelock:
 	 * debugger on a different CPU via a single step
 	 */
 	if (atomic_read(&kgdb_cpu_doing_single_step) != -1 &&
-	    atomic_read(&kgdb_cpu_doing_single_step) != cpu) {
-
+	    kgdb_info[cpu].task &&
+	    kgdb_info[cpu].task->pid != kgdb_sstep_pid) {
 		atomic_set(&kgdb_active, -1);
-		touch_softlockup_watchdog();
+		touch_softlockup_watchdog_sync();
 		clocksource_touch_watchdog();
 		local_irq_restore(flags);
 
@@ -1524,9 +1532,16 @@ acquirelock:
 	}
 
 kgdb_restore:
+	if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
+		int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step);
+		if (kgdb_info[sstep_cpu].task)
+			kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid;
+		else
+			kgdb_sstep_pid = 0;
+	}
 	/* Free kgdb_active */
 	atomic_set(&kgdb_active, -1);
-	touch_softlockup_watchdog();
+	touch_softlockup_watchdog_sync();
 	clocksource_touch_watchdog();
 	local_irq_restore(flags);
 

kernel/softlockup.c

@@ -79,6 +79,14 @@ void touch_softlockup_watchdog(void)
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
+static int softlock_touch_sync[NR_CPUS];
+
+void touch_softlockup_watchdog_sync(void)
+{
+	softlock_touch_sync[raw_smp_processor_id()] = 1;
+	__raw_get_cpu_var(touch_timestamp) = 0;
+}
+
 void touch_all_softlockup_watchdogs(void)
 {
 	int cpu;
@@ -118,6 +126,14 @@ void softlockup_tick(void)
 	}
 
 	if (touch_timestamp == 0) {
+		if (unlikely(softlock_touch_sync[this_cpu])) {
+			/*
+			 * If the time stamp was touched atomically
+			 * make sure the scheduler tick is up to date.
+			 */
+			softlock_touch_sync[this_cpu] = 0;
+			sched_clock_tick();
+		}
 		__touch_softlockup_watchdog();
 		return;
 	}