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

7 files changed, 85 insertions, 127 deletions

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index de407c7..fec596d 100644
--- a/kernel/debug/debug_core.c
+++ b/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 @@ acquirelock:
 	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 @@ cpu_loop:
 			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 @@ return_normal:
 				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 @@ return_normal:
 	    (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 @@ return_normal:
 	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 @@ return_normal:
 	/*
 	 * 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 @@ cpu_master_loop:
 		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 @@ cpu_master_loop:
 	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 @@ kgdb_restore:
 		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
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index c5d753d..3494c28 100644
--- a/kernel/debug/debug_core.h
+++ b/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[];
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index bf6e827..dd0b1b7 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -86,7 +86,7 @@ int kdb_stub(struct kgdb_state *ks)
 	}
 	/* Set initial kdb state variables */
 	KDB_STATE_CLEAR(KGDB_TRANS);
-	kdb_initial_cpu = ks->cpu;
+	kdb_initial_cpu = atomic_read(&kgdb_active);
 	kdb_current_task = kgdb_info[ks->cpu].task;
 	kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
 	/* Remove any breakpoints as needed by kdb and clear single step */
@@ -105,7 +105,6 @@ int kdb_stub(struct kgdb_state *ks)
 		ks->pass_exception = 1;
 		KDB_FLAG_SET(CATASTROPHIC);
 	}
-	kdb_initial_cpu = ks->cpu;
 	if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
 		KDB_STATE_CLEAR(SSBPT);
 		KDB_STATE_CLEAR(DOING_SS);
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index c9b7f4f9..96fdaac 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -823,4 +823,4 @@ int kdb_printf(const char *fmt, ...)
 
 	return r;
 }
-
+EXPORT_SYMBOL_GPL(kdb_printf);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index caf057a..d7bda21 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1749,13 +1749,13 @@ static int kdb_go(int argc, const char **argv)
 	int nextarg;
 	long offset;
 
+	if (raw_smp_processor_id() != kdb_initial_cpu) {
+		kdb_printf("go must execute on the entry cpu, "
+			   "please use \"cpu %d\" and then execute go\n",
+			   kdb_initial_cpu);
+		return KDB_BADCPUNUM;
+	}
 	if (argc == 1) {
-		if (raw_smp_processor_id() != kdb_initial_cpu) {
-			kdb_printf("go <address> must be issued from the "
-				   "initial cpu, do cpu %d first\n",
-				   kdb_initial_cpu);
-			return KDB_ARGCOUNT;
-		}
 		nextarg = 1;
 		diag = kdbgetaddrarg(argc, argv, &nextarg,
 				     &addr, &offset, NULL);
@@ -2783,6 +2783,8 @@ int kdb_register_repeat(char *cmd,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(kdb_register_repeat);
+
 
 /*
  * kdb_register - Compatibility register function for commands that do
@@ -2805,6 +2807,7 @@ int kdb_register(char *cmd,
 	return kdb_register_repeat(cmd, func, usage, help, minlen,
 				   KDB_REPEAT_NONE);
 }
+EXPORT_SYMBOL_GPL(kdb_register);
 
 /*
  * kdb_unregister - This function is used to unregister a kernel
@@ -2823,7 +2826,7 @@ int kdb_unregister(char *cmd)
 	/*
 	 *  find the command.
 	 */
-	for (i = 0, kp = kdb_commands; i < kdb_max_commands; i++, kp++) {
+	for_each_kdbcmd(kp, i) {
 		if (kp->cmd_name && (strcmp(kp->cmd_name, cmd) == 0)) {
 			kp->cmd_name = NULL;
 			return 0;
@@ -2833,6 +2836,7 @@ int kdb_unregister(char *cmd)
 	/* Couldn't find it.  */
 	return 1;
 }
+EXPORT_SYMBOL_GPL(kdb_unregister);
 
 /* Initialize the kdb command table. */
 static void __init kdb_inittab(void)
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index be775f7..35d69ed 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -15,29 +15,6 @@
 #include <linux/kgdb.h>
 #include "../debug_core.h"
 
-/* Kernel Debugger Error codes.  Must not overlap with command codes. */
-#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)
-
 /* Kernel Debugger Command codes.  Must not overlap with error codes. */
 #define KDB_CMD_GO	(-1001)
 #define KDB_CMD_CPU	(-1002)
@@ -93,17 +70,6 @@
  */
 #define KDB_MAXBPT	16
 
-/* Maximum number of arguments to a function  */
-#define KDB_MAXARGS    16
-
-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 **);
-
 /* Symbol table format returned by kallsyms. */
 typedef struct __ksymtab {
 		unsigned long value;	/* Address of symbol */
@@ -123,11 +89,6 @@ extern int kallsyms_symbol_next(char *prefix_name, int flag);
 extern int kallsyms_symbol_complete(char *prefix_name, int max_len);
 
 /* Exported Symbols for kernel loadable modules to use. */
-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 *);
-
 extern int kdb_getarea_size(void *, unsigned long, size_t);
 extern int kdb_putarea_size(unsigned long, void *, size_t);
 
@@ -144,6 +105,7 @@ extern int kdb_getword(unsigned long *, unsigned long, size_t);
 extern int kdb_putword(unsigned long, unsigned long, size_t);
 
 extern int kdbgetularg(const char *, unsigned long *);
+extern int kdbgetu64arg(const char *, u64 *);
 extern char *kdbgetenv(const char *);
 extern int kdbgetaddrarg(int, const char **, int*, unsigned long *,
 			 long *, char **);
@@ -255,14 +217,6 @@ extern void kdb_ps1(const struct task_struct *p);
 extern void kdb_print_nameval(const char *name, unsigned long val);
 extern void kdb_send_sig_info(struct task_struct *p, struct siginfo *info);
 extern void kdb_meminfo_proc_show(void);
-#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 */
 extern char *kdb_getstr(char *, size_t, char *);
 
 /* Defines for kdb_symbol_print */
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
index 7b8ecd7..3c5c5df 100644
--- a/kernel/trace/trace_kdb.c
+++ b/kernel/trace/trace_kdb.c
@@ -13,7 +13,6 @@
 #include <linux/kdb.h>
 #include <linux/ftrace.h>
 
-#include "../debug/kdb/kdb_private.h"
 #include "trace.h"
 #include "trace_output.h"