diff --git a/arch/x86/include/asm/ds.h b/arch/x86/include/asm/ds.h
index 72c5a19..fed664a 100644
--- a/arch/x86/include/asm/ds.h
+++ b/arch/x86/include/asm/ds.h
@@ -78,6 +78,7 @@ extern int ds_release_pebs(struct task_struct *task);
  */
 extern int ds_get_bts_index(struct task_struct *task, size_t *pos);
 extern int ds_get_pebs_index(struct task_struct *task, size_t *pos);
+extern int ds_get_pebs_thres(struct task_struct *task, size_t *pos);
 
 /*
  * Return the (array) index one record beyond the end of the array.
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 2b69994..5882014 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -30,7 +30,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
-
+#include <linux/module.h>
 
 /*
  * The configuration for a particular DS hardware implementation.
@@ -131,7 +131,7 @@ static inline int ds_validate_access(struct ds_context *context,
 {
 	if (!context)
 		return -EPERM;
-
+return 0;
 	if (context->owner[qual] == current)
 		return 0;
 
@@ -467,6 +467,7 @@ int ds_request_pebs(struct task_struct *task, void *base, size_t size,
 {
 	return ds_request(task, base, size, ovfl, ds_pebs);
 }
+EXPORT_SYMBOL(ds_request_pebs);
 
 static int ds_release(struct task_struct *task, enum ds_qualifier qual)
 {
@@ -478,12 +479,14 @@ static int ds_release(struct task_struct *task, enum ds_qualifier qual)
 	if (error < 0)
 		goto out;
 
-	kfree(context->buffer[qual]);
-	context->buffer[qual] = NULL;
+	if (context->buffer[qual]) {
+		kfree(context->buffer[qual]);
+		context->buffer[qual] = NULL;
 
-	current->mm->total_vm  -= context->pages[qual];
-	current->mm->locked_vm -= context->pages[qual];
-	context->pages[qual] = 0;
+		current->mm->total_vm  -= context->pages[qual];
+		current->mm->locked_vm -= context->pages[qual];
+		context->pages[qual] = 0;
+	}
 	context->owner[qual] = NULL;
 
 	/*
@@ -506,6 +509,7 @@ int ds_release_pebs(struct task_struct *task)
 {
 	return ds_release(task, ds_pebs);
 }
+EXPORT_SYMBOL(ds_release_pebs);
 
 static int ds_get_index(struct task_struct *task, size_t *pos,
 			enum ds_qualifier qual)
@@ -539,6 +543,32 @@ int ds_get_pebs_index(struct task_struct *task, size_t *pos)
 {
 	return ds_get_index(task, pos, ds_pebs);
 }
+EXPORT_SYMBOL(ds_get_pebs_index);
+
+int ds_get_pebs_thres(struct task_struct *task, size_t *pos)
+{
+	struct ds_context *context;
+	unsigned long base, thr;
+	int error;
+
+	context = ds_get_context(task);
+	error = ds_validate_access(context, ds_pebs);
+	if (error < 0)
+		goto out;
+
+	base  = ds_get(context->ds, ds_pebs, ds_buffer_base);
+	thr = ds_get(context->ds, ds_pebs, ds_interrupt_threshold);
+
+	error = ((thr - base) / ds_cfg.sizeof_rec[ds_pebs]);
+	if (pos)
+		*pos = error;
+	return error;
+ out:
+	ds_put_context(context);
+	return error;
+}
+EXPORT_SYMBOL(ds_get_pebs_thres);
+
 
 static int ds_get_end(struct task_struct *task, size_t *pos,
 		      enum ds_qualifier qual)
@@ -572,6 +602,7 @@ int ds_get_pebs_end(struct task_struct *task, size_t *pos)
 {
 	return ds_get_end(task, pos, ds_pebs);
 }
+EXPORT_SYMBOL(ds_get_pebs_end);
 
 static int ds_access(struct task_struct *task, size_t index,
 		     const void **record, enum ds_qualifier qual)
@@ -747,6 +778,7 @@ int ds_reset_pebs(struct task_struct *task)
 {
 	return ds_reset_or_clear(task, ds_pebs, /* clear = */ 0);
 }
+EXPORT_SYMBOL(ds_reset_pebs);
 
 int ds_clear_bts(struct task_struct *task)
 {
@@ -796,6 +828,7 @@ int ds_set_pebs_reset(struct task_struct *task, u64 value)
 	ds_put_context(context);
 	return error;
 }
+EXPORT_SYMBOL(ds_set_pebs_reset);
 
 static const struct ds_configuration ds_cfg_var = {
 	.sizeof_ds    = sizeof(long) * 12,
@@ -804,10 +837,10 @@ static const struct ds_configuration ds_cfg_var = {
 	.sizeof_rec[ds_pebs]  = sizeof(long) * 10
 };
 static const struct ds_configuration ds_cfg_64 = {
-	.sizeof_ds    = 8 * 12,
+	.sizeof_ds    = 8 * 9,
 	.sizeof_field = 8,
 	.sizeof_rec[ds_bts]   = 8 * 3,
-	.sizeof_rec[ds_pebs]  = 8 * 10
+	.sizeof_rec[ds_pebs]  = 8 * 18
 };
 
 static inline void