Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel…

…/git/jwessel/linux-2.6-kgdb

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  kdb,debug_core: adjust master cpu switch logic against new debug_core locking
  debug_core: refactor locking for master/slave cpus
  x86,kgdb: remove unnecessary call to kgdb_correct_hw_break()
  debug_core: disable hw_breakpoints on all cores in kgdb_cpu_enter()
  kdb,kgdb: fix sparse fixups
  kdb: Fix oops in kdb_unregister
  kdb,ftdump: Remove reference to internal kdb include
  kdb: Allow kernel loadable modules to add kdb shell functions
  debug_core: stop rcu warnings on kernel resume
  debug_core: move all watch dog syncs to a single function
  x86,kgdb: fix debugger hw breakpoint test regression in 2.6.35

arch/x86/kernel/kgdb.c

@@ -477,8 +477,6 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
 				   raw_smp_processor_id());
 		}
 
-		kgdb_correct_hw_break();
-
 		return 0;
 	}
 
@@ -621,7 +619,12 @@ int kgdb_arch_init(void)
 static void kgdb_hw_overflow_handler(struct perf_event *event, int nmi,
 		struct perf_sample_data *data, struct pt_regs *regs)
 {
-	kgdb_ll_trap(DIE_DEBUG, "debug", regs, 0, 0, SIGTRAP);
+	struct task_struct *tsk = current;
+	int i;
+
+	for (i = 0; i < 4; i++)
+		if (breakinfo[i].enabled)
+			tsk->thread.debugreg6 |= (DR_TRAP0 << i);
 }
 
 void kgdb_arch_late(void)
@@ -644,7 +647,7 @@ void kgdb_arch_late(void)
 		if (breakinfo[i].pev)
 			continue;
 		breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
-		if (IS_ERR(breakinfo[i].pev)) {
+		if (IS_ERR((void * __force)breakinfo[i].pev)) {
 			printk(KERN_ERR "kgdb: Could not allocate hw"
 			       "breakpoints\nDisabling the kernel debugger\n");
 			breakinfo[i].pev = NULL;

drivers/serial/kgdboc.c

@@ -243,7 +243,7 @@ static struct kgdb_io kgdboc_io_ops = {
 
 #ifdef CONFIG_KGDB_SERIAL_CONSOLE
 /* This is only available if kgdboc is a built in for early debugging */
-int __init kgdboc_early_init(char *opt)
+static int __init kgdboc_early_init(char *opt)
 {
 	/* save the first character of the config string because the
 	 * init routine can destroy it.

include/linux/kdb.h

@@ -28,6 +28,41 @@ extern int kdb_poll_idx;
 extern int kdb_initial_cpu;
 extern atomic_t kdb_event;
 
+/* Types and messages used for dynamically added kdb shell commands */
+
+#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)
+#define KDB_BADWIDTH	(-3)
+#define KDB_BADRADIX	(-4)
+#define KDB_NOTENV	(-5)
+#define KDB_NOENVVALUE	(-6)
+#define KDB_NOTIMP	(-7)
+#define KDB_ENVFULL	(-8)
+#define KDB_ENVBUFFULL	(-9)
+#define KDB_TOOMANYBPT	(-10)
+#define KDB_TOOMANYDBREGS (-11)
+#define KDB_DUPBPT	(-12)
+#define KDB_BPTNOTFOUND	(-13)
+#define KDB_BADMODE	(-14)
+#define KDB_BADINT	(-15)
+#define KDB_INVADDRFMT  (-16)
+#define KDB_BADREG      (-17)
+#define KDB_BADCPUNUM   (-18)
+#define KDB_BADLENGTH	(-19)
+#define KDB_NOBP	(-20)
+#define KDB_BADADDR	(-21)
+
 /*
  * kdb_diemsg
  *
@@ -104,10 +139,26 @@ int kdb_process_cpu(const struct task_struct *p)
 
 /* kdb access to register set for stack dumping */
 extern struct pt_regs *kdb_current_regs;
+#ifdef CONFIG_KALLSYMS
+extern const char *kdb_walk_kallsyms(loff_t *pos);
+#else /* ! CONFIG_KALLSYMS */
+static inline const char *kdb_walk_kallsyms(loff_t *pos)
+{
+	return NULL;
+}
+#endif /* ! CONFIG_KALLSYMS */
 
+/* Dynamic kdb shell command registration */
+extern int kdb_register(char *, kdb_func_t, char *, char *, short);
+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)
 #endif	/* CONFIG_KGDB_KDB */
 enum {
 	KDB_NOT_INITIALIZED,

kernel/debug/debug_core.c

@@ -47,6 +47,7 @@
 #include <linux/pid.h>
 #include <linux/smp.h>
 #include <linux/mm.h>
+#include <linux/rcupdate.h>
 
 #include <asm/cacheflush.h>
 #include <asm/byteorder.h>
@@ -109,13 +110,15 @@ static struct kgdb_bkpt		kgdb_break[KGDB_MAX_BREAKPOINTS] = {
  */
 atomic_t			kgdb_active = ATOMIC_INIT(-1);
 EXPORT_SYMBOL_GPL(kgdb_active);
+static DEFINE_RAW_SPINLOCK(dbg_master_lock);
+static DEFINE_RAW_SPINLOCK(dbg_slave_lock);
 
 /*
  * We use NR_CPUs not PERCPU, in case kgdb is used to debug early
  * bootup code (which might not have percpu set up yet):
  */
-static atomic_t			passive_cpu_wait[NR_CPUS];
-static atomic_t			cpu_in_kgdb[NR_CPUS];
+static atomic_t			masters_in_kgdb;
+static atomic_t			slaves_in_kgdb;
 static atomic_t			kgdb_break_tasklet_var;
 atomic_t			kgdb_setting_breakpoint;
 
@@ -457,26 +460,32 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
 	return 1;
 }
 
-static void dbg_cpu_switch(int cpu, int next_cpu)
+static void dbg_touch_watchdogs(void)
 {
-	/* Mark the cpu we are switching away from as a slave when it
-	 * holds the kgdb_active token.  This must be done so that the
-	 * that all the cpus wait in for the debug core will not enter
-	 * again as the master. */
-	if (cpu == atomic_read(&kgdb_active)) {
-		kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
-		kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER;
-	}
-	kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER;
+	touch_softlockup_watchdog_sync();
+	clocksource_touch_watchdog();
+	rcu_cpu_stall_reset();
 }
 
-static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
+static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
+		int exception_state)
 {
 	unsigned long flags;
 	int sstep_tries = 100;
 	int error;
-	int i, cpu;
+	int cpu;
 	int trace_on = 0;
+	int online_cpus = num_online_cpus();
+
+	kgdb_info[ks->cpu].enter_kgdb++;
+	kgdb_info[ks->cpu].exception_state |= exception_state;
+
+	if (exception_state == DCPU_WANT_MASTER)
+		atomic_inc(&masters_in_kgdb);
+	else
+		atomic_inc(&slaves_in_kgdb);
+	kgdb_disable_hw_debug(ks->linux_regs);
+
 acquirelock:
 	/*
 	 * Interrupts will be restored by the 'trap return' code, except when
@@ -489,14 +498,15 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	kgdb_info[cpu].task = current;
 	kgdb_info[cpu].ret_state = 0;
 	kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT;
-	/*
-	 * Make sure the above info reaches the primary CPU before
-	 * our cpu_in_kgdb[] flag setting does:
-	 */
-	atomic_inc(&cpu_in_kgdb[cpu]);
 
-	if (exception_level == 1)
+	/* Make sure the above info reaches the primary CPU */
+	smp_mb();
+
+	if (exception_level == 1) {
+		if (raw_spin_trylock(&dbg_master_lock))
+			atomic_xchg(&kgdb_active, cpu);
 		goto cpu_master_loop;
+	}
 
 	/*
 	 * CPU will loop if it is a slave or request to become a kgdb
@@ -508,10 +518,12 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 			kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER;
 			goto cpu_master_loop;
 		} else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) {
-			if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu)
+			if (raw_spin_trylock(&dbg_master_lock)) {
+				atomic_xchg(&kgdb_active, cpu);
 				break;
+			}
 		} else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) {
-			if (!atomic_read(&passive_cpu_wait[cpu]))
+			if (!raw_spin_is_locked(&dbg_slave_lock))
 				goto return_normal;
 		} else {
 return_normal:
@@ -522,9 +534,12 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 				arch_kgdb_ops.correct_hw_break();
 			if (trace_on)
 				tracing_on();
-			atomic_dec(&cpu_in_kgdb[cpu]);
-			touch_softlockup_watchdog_sync();
-			clocksource_touch_watchdog();
+			kgdb_info[cpu].exception_state &=
+				~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
+			kgdb_info[cpu].enter_kgdb--;
+			smp_mb__before_atomic_dec();
+			atomic_dec(&slaves_in_kgdb);
+			dbg_touch_watchdogs();
 			local_irq_restore(flags);
 			return 0;
 		}
@@ -541,8 +556,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	    (kgdb_info[cpu].task &&
 	     kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) {
 		atomic_set(&kgdb_active, -1);
-		touch_softlockup_watchdog_sync();
-		clocksource_touch_watchdog();
+		raw_spin_unlock(&dbg_master_lock);
+		dbg_touch_watchdogs();
 		local_irq_restore(flags);
 
 		goto acquirelock;
@@ -563,16 +578,12 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	if (dbg_io_ops->pre_exception)
 		dbg_io_ops->pre_exception();
 
-	kgdb_disable_hw_debug(ks->linux_regs);
-
 	/*
 	 * Get the passive CPU lock which will hold all the non-primary
 	 * CPU in a spin state while the debugger is active
 	 */
-	if (!kgdb_single_step) {
-		for (i = 0; i < NR_CPUS; i++)
-			atomic_inc(&passive_cpu_wait[i]);
-	}
+	if (!kgdb_single_step)
+		raw_spin_lock(&dbg_slave_lock);
 
 #ifdef CONFIG_SMP
 	/* Signal the other CPUs to enter kgdb_wait() */
@@ -583,10 +594,9 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	/*
 	 * Wait for the other CPUs to be notified and be waiting for us:
 	 */
-	for_each_online_cpu(i) {
-		while (kgdb_do_roundup && !atomic_read(&cpu_in_kgdb[i]))
-			cpu_relax();
-	}
+	while (kgdb_do_roundup && (atomic_read(&masters_in_kgdb) +
+				atomic_read(&slaves_in_kgdb)) != online_cpus)
+		cpu_relax();
 
 	/*
 	 * At this point the primary processor is completely
@@ -615,7 +625,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 		if (error == DBG_PASS_EVENT) {
 			dbg_kdb_mode = !dbg_kdb_mode;
 		} else if (error == DBG_SWITCH_CPU_EVENT) {
-			dbg_cpu_switch(cpu, dbg_switch_cpu);
+			kgdb_info[dbg_switch_cpu].exception_state |=
+				DCPU_NEXT_MASTER;
 			goto cpu_loop;
 		} else {
 			kgdb_info[cpu].ret_state = error;
@@ -627,24 +638,11 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 	if (dbg_io_ops->post_exception)
 		dbg_io_ops->post_exception();
 
-	atomic_dec(&cpu_in_kgdb[ks->cpu]);
-
 	if (!kgdb_single_step) {
-		for (i = NR_CPUS-1; i >= 0; i--)
-			atomic_dec(&passive_cpu_wait[i]);
-		/*
-		 * Wait till all the CPUs have quit from the debugger,
-		 * but allow a CPU that hit an exception and is
-		 * waiting to become the master to remain in the debug
-		 * core.
-		 */
-		for_each_online_cpu(i) {
-			while (kgdb_do_roundup &&
-			       atomic_read(&cpu_in_kgdb[i]) &&
-			       !(kgdb_info[i].exception_state &
-				 DCPU_WANT_MASTER))
-				cpu_relax();
-		}
+		raw_spin_unlock(&dbg_slave_lock);
+		/* Wait till all the CPUs have quit from the debugger. */
+		while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb))
+			cpu_relax();
 	}
 
 kgdb_restore:
@@ -655,12 +653,20 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
 		else
 			kgdb_sstep_pid = 0;
 	}
+	if (arch_kgdb_ops.correct_hw_break)
+		arch_kgdb_ops.correct_hw_break();
 	if (trace_on)
 		tracing_on();
+
+	kgdb_info[cpu].exception_state &=
+		~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
+	kgdb_info[cpu].enter_kgdb--;
+	smp_mb__before_atomic_dec();
+	atomic_dec(&masters_in_kgdb);
 	/* Free kgdb_active */
 	atomic_set(&kgdb_active, -1);
-	touch_softlockup_watchdog_sync();
-	clocksource_touch_watchdog();
+	raw_spin_unlock(&dbg_master_lock);
+	dbg_touch_watchdogs();
 	local_irq_restore(flags);
 
 	return kgdb_info[cpu].ret_state;
@@ -678,7 +684,6 @@ 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;
 
 	ks->cpu			= raw_smp_processor_id();
 	ks->ex_vector		= evector;
@@ -689,11 +694,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 
 	if (kgdb_reenter_check(ks))
 		return 0; /* Ouch, double exception ! */
-	kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER;
-	ret = kgdb_cpu_enter(ks, regs);
-	kgdb_info[ks->cpu].exception_state &= ~(DCPU_WANT_MASTER |
-						DCPU_IS_SLAVE);
-	return ret;
+	if (kgdb_info[ks->cpu].enter_kgdb != 0)
+		return 0;
+
+	return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
 }
 
 int kgdb_nmicallback(int cpu, void *regs)
@@ -706,12 +710,9 @@ int kgdb_nmicallback(int cpu, void *regs)
 	ks->cpu			= cpu;
 	ks->linux_regs		= regs;
 
-	if (!atomic_read(&cpu_in_kgdb[cpu]) &&
-	    atomic_read(&kgdb_active) != -1 &&
-	    atomic_read(&kgdb_active) != cpu) {
-		kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
-		kgdb_cpu_enter(ks, regs);
-		kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE;
+	if (kgdb_info[ks->cpu].enter_kgdb == 0 &&
+			raw_spin_is_locked(&dbg_master_lock)) {
+		kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE);
 		return 0;
 	}
 #endif

kernel/debug/debug_core.h

@@ -40,6 +40,7 @@ struct debuggerinfo_struct {
 	int			exception_state;
 	int			ret_state;
 	int			irq_depth;
+	int			enter_kgdb;
 };
 
 extern struct debuggerinfo_struct kgdb_info[];