Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1583 insertions, 0 deletions

diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
new file mode 100644
index 000000000..d7a82066a
--- /dev/null
+++ b/arch/s390/kernel/debug.c
@@ -0,0 +1,1583 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *   S/390 debug facility
+ *
+ *    Copyright IBM Corp. 1999, 2020
+ *
+ *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
+ *		 Holger Smolinski (Holger.Smolinski@de.ibm.com)
+ *
+ *    Bugreports to: <Linux390@de.ibm.com>
+ */
+
+#define KMSG_COMPONENT "s390dbf"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <linux/sysctl.h>
+#include <linux/uaccess.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/minmax.h>
+#include <linux/debugfs.h>
+
+#include <asm/debug.h>
+
+#define DEBUG_PROLOG_ENTRY -1
+
+#define ALL_AREAS 0 /* copy all debug areas */
+#define NO_AREAS  1 /* copy no debug areas */
+
+/* typedefs */
+
+typedef struct file_private_info {
+	loff_t offset;			/* offset of last read in file */
+	int    act_area;		/* number of last formated area */
+	int    act_page;		/* act page in given area */
+	int    act_entry;		/* last formated entry (offset */
+					/* relative to beginning of last */
+					/* formated page) */
+	size_t act_entry_offset;	/* up to this offset we copied */
+					/* in last read the last formated */
+					/* entry to userland */
+	char   temp_buf[2048];		/* buffer for output */
+	debug_info_t *debug_info_org;	/* original debug information */
+	debug_info_t *debug_info_snap;	/* snapshot of debug information */
+	struct debug_view *view;	/* used view of debug info */
+} file_private_info_t;
+
+typedef struct {
+	char *string;
+	/*
+	 * This assumes that all args are converted into longs
+	 * on L/390 this is the case for all types of parameter
+	 * except of floats, and long long (32 bit)
+	 *
+	 */
+	long args[0];
+} debug_sprintf_entry_t;
+
+/* internal function prototyes */
+
+static int debug_init(void);
+static ssize_t debug_output(struct file *file, char __user *user_buf,
+			    size_t user_len, loff_t *offset);
+static ssize_t debug_input(struct file *file, const char __user *user_buf,
+			   size_t user_len, loff_t *offset);
+static int debug_open(struct inode *inode, struct file *file);
+static int debug_close(struct inode *inode, struct file *file);
+static debug_info_t *debug_info_create(const char *name, int pages_per_area,
+				       int nr_areas, int buf_size, umode_t mode);
+static void debug_info_get(debug_info_t *);
+static void debug_info_put(debug_info_t *);
+static int debug_prolog_level_fn(debug_info_t *id,
+				 struct debug_view *view, char *out_buf);
+static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_buf_size, loff_t *offset);
+static int debug_prolog_pages_fn(debug_info_t *id,
+				 struct debug_view *view, char *out_buf);
+static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_buf_size, loff_t *offset);
+static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_buf_size, loff_t *offset);
+static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
+				     char *out_buf, const char *in_buf);
+static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
+				   char *out_buf, debug_sprintf_entry_t *curr_event);
+static void debug_areas_swap(debug_info_t *a, debug_info_t *b);
+static void debug_events_append(debug_info_t *dest, debug_info_t *src);
+
+/* globals */
+
+struct debug_view debug_hex_ascii_view = {
+	"hex_ascii",
+	NULL,
+	&debug_dflt_header_fn,
+	&debug_hex_ascii_format_fn,
+	NULL,
+	NULL
+};
+EXPORT_SYMBOL(debug_hex_ascii_view);
+
+static struct debug_view debug_level_view = {
+	"level",
+	&debug_prolog_level_fn,
+	NULL,
+	NULL,
+	&debug_input_level_fn,
+	NULL
+};
+
+static struct debug_view debug_pages_view = {
+	"pages",
+	&debug_prolog_pages_fn,
+	NULL,
+	NULL,
+	&debug_input_pages_fn,
+	NULL
+};
+
+static struct debug_view debug_flush_view = {
+	"flush",
+	NULL,
+	NULL,
+	NULL,
+	&debug_input_flush_fn,
+	NULL
+};
+
+struct debug_view debug_sprintf_view = {
+	"sprintf",
+	NULL,
+	&debug_dflt_header_fn,
+	(debug_format_proc_t *)&debug_sprintf_format_fn,
+	NULL,
+	NULL
+};
+EXPORT_SYMBOL(debug_sprintf_view);
+
+/* used by dump analysis tools to determine version of debug feature */
+static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;
+
+/* static globals */
+
+static debug_info_t *debug_area_first;
+static debug_info_t *debug_area_last;
+static DEFINE_MUTEX(debug_mutex);
+
+static int initialized;
+static int debug_critical;
+
+static const struct file_operations debug_file_ops = {
+	.owner	 = THIS_MODULE,
+	.read	 = debug_output,
+	.write	 = debug_input,
+	.open	 = debug_open,
+	.release = debug_close,
+	.llseek  = no_llseek,
+};
+
+static struct dentry *debug_debugfs_root_entry;
+
+/* functions */
+
+/*
+ * debug_areas_alloc
+ * - Debug areas are implemented as a threedimensonal array:
+ *   areas[areanumber][pagenumber][pageoffset]
+ */
+
+static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
+{
+	debug_entry_t ***areas;
+	int i, j;
+
+	areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
+	if (!areas)
+		goto fail_malloc_areas;
+	for (i = 0; i < nr_areas; i++) {
+		/* GFP_NOWARN to avoid user triggerable WARN, we handle fails */
+		areas[i] = kmalloc_array(pages_per_area,
+					 sizeof(debug_entry_t *),
+					 GFP_KERNEL | __GFP_NOWARN);
+		if (!areas[i])
+			goto fail_malloc_areas2;
+		for (j = 0; j < pages_per_area; j++) {
+			areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
+			if (!areas[i][j]) {
+				for (j--; j >= 0 ; j--)
+					kfree(areas[i][j]);
+				kfree(areas[i]);
+				goto fail_malloc_areas2;
+			}
+		}
+	}
+	return areas;
+
+fail_malloc_areas2:
+	for (i--; i >= 0; i--) {
+		for (j = 0; j < pages_per_area; j++)
+			kfree(areas[i][j]);
+		kfree(areas[i]);
+	}
+	kfree(areas);
+fail_malloc_areas:
+	return NULL;
+}
+
+/*
+ * debug_info_alloc
+ * - alloc new debug-info
+ */
+static debug_info_t *debug_info_alloc(const char *name, int pages_per_area,
+				      int nr_areas, int buf_size, int level,
+				      int mode)
+{
+	debug_info_t *rc;
+
+	/* alloc everything */
+	rc = kmalloc(sizeof(debug_info_t), GFP_KERNEL);
+	if (!rc)
+		goto fail_malloc_rc;
+	rc->active_entries = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
+	if (!rc->active_entries)
+		goto fail_malloc_active_entries;
+	rc->active_pages = kcalloc(nr_areas, sizeof(int), GFP_KERNEL);
+	if (!rc->active_pages)
+		goto fail_malloc_active_pages;
+	if ((mode == ALL_AREAS) && (pages_per_area != 0)) {
+		rc->areas = debug_areas_alloc(pages_per_area, nr_areas);
+		if (!rc->areas)
+			goto fail_malloc_areas;
+	} else {
+		rc->areas = NULL;
+	}
+
+	/* initialize members */
+	spin_lock_init(&rc->lock);
+	rc->pages_per_area = pages_per_area;
+	rc->nr_areas	   = nr_areas;
+	rc->active_area    = 0;
+	rc->level	   = level;
+	rc->buf_size	   = buf_size;
+	rc->entry_size	   = sizeof(debug_entry_t) + buf_size;
+	strscpy(rc->name, name, sizeof(rc->name));
+	memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));
+	memset(rc->debugfs_entries, 0, DEBUG_MAX_VIEWS * sizeof(struct dentry *));
+	refcount_set(&(rc->ref_count), 0);
+
+	return rc;
+
+fail_malloc_areas:
+	kfree(rc->active_pages);
+fail_malloc_active_pages:
+	kfree(rc->active_entries);
+fail_malloc_active_entries:
+	kfree(rc);
+fail_malloc_rc:
+	return NULL;
+}
+
+/*
+ * debug_areas_free
+ * - free all debug areas
+ */
+static void debug_areas_free(debug_info_t *db_info)
+{
+	int i, j;
+
+	if (!db_info->areas)
+		return;
+	for (i = 0; i < db_info->nr_areas; i++) {
+		for (j = 0; j < db_info->pages_per_area; j++)
+			kfree(db_info->areas[i][j]);
+		kfree(db_info->areas[i]);
+	}
+	kfree(db_info->areas);
+	db_info->areas = NULL;
+}
+
+/*
+ * debug_info_free
+ * - free memory debug-info
+ */
+static void debug_info_free(debug_info_t *db_info)
+{
+	debug_areas_free(db_info);
+	kfree(db_info->active_entries);
+	kfree(db_info->active_pages);
+	kfree(db_info);
+}
+
+/*
+ * debug_info_create
+ * - create new debug-info
+ */
+
+static debug_info_t *debug_info_create(const char *name, int pages_per_area,
+				       int nr_areas, int buf_size, umode_t mode)
+{
+	debug_info_t *rc;
+
+	rc = debug_info_alloc(name, pages_per_area, nr_areas, buf_size,
+			      DEBUG_DEFAULT_LEVEL, ALL_AREAS);
+	if (!rc)
+		goto out;
+
+	rc->mode = mode & ~S_IFMT;
+	refcount_set(&rc->ref_count, 1);
+out:
+	return rc;
+}
+
+/*
+ * debug_info_copy
+ * - copy debug-info
+ */
+static debug_info_t *debug_info_copy(debug_info_t *in, int mode)
+{
+	unsigned long flags;
+	debug_info_t *rc;
+	int i, j;
+
+	/* get a consistent copy of the debug areas */
+	do {
+		rc = debug_info_alloc(in->name, in->pages_per_area,
+			in->nr_areas, in->buf_size, in->level, mode);
+		spin_lock_irqsave(&in->lock, flags);
+		if (!rc)
+			goto out;
+		/* has something changed in the meantime ? */
+		if ((rc->pages_per_area == in->pages_per_area) &&
+		    (rc->nr_areas == in->nr_areas)) {
+			break;
+		}
+		spin_unlock_irqrestore(&in->lock, flags);
+		debug_info_free(rc);
+	} while (1);
+
+	if (mode == NO_AREAS)
+		goto out;
+
+	for (i = 0; i < in->nr_areas; i++) {
+		for (j = 0; j < in->pages_per_area; j++)
+			memcpy(rc->areas[i][j], in->areas[i][j], PAGE_SIZE);
+	}
+out:
+	spin_unlock_irqrestore(&in->lock, flags);
+	return rc;
+}
+
+/*
+ * debug_info_get
+ * - increments reference count for debug-info
+ */
+static void debug_info_get(debug_info_t *db_info)
+{
+	if (db_info)
+		refcount_inc(&db_info->ref_count);
+}
+
+/*
+ * debug_info_put:
+ * - decreases reference count for debug-info and frees it if necessary
+ */
+static void debug_info_put(debug_info_t *db_info)
+{
+	if (!db_info)
+		return;
+	if (refcount_dec_and_test(&db_info->ref_count))
+		debug_info_free(db_info);
+}
+
+/*
+ * debug_format_entry:
+ * - format one debug entry and return size of formated data
+ */
+static int debug_format_entry(file_private_info_t *p_info)
+{
+	debug_info_t *id_snap	= p_info->debug_info_snap;
+	struct debug_view *view = p_info->view;
+	debug_entry_t *act_entry;
+	size_t len = 0;
+
+	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
+		/* print prolog */
+		if (view->prolog_proc)
+			len += view->prolog_proc(id_snap, view, p_info->temp_buf);
+		goto out;
+	}
+	if (!id_snap->areas) /* this is true, if we have a prolog only view */
+		goto out;    /* or if 'pages_per_area' is 0 */
+	act_entry = (debug_entry_t *) ((char *)id_snap->areas[p_info->act_area]
+				       [p_info->act_page] + p_info->act_entry);
+
+	if (act_entry->clock == 0LL)
+		goto out; /* empty entry */
+	if (view->header_proc)
+		len += view->header_proc(id_snap, view, p_info->act_area,
+					 act_entry, p_info->temp_buf + len);
+	if (view->format_proc)
+		len += view->format_proc(id_snap, view, p_info->temp_buf + len,
+					 DEBUG_DATA(act_entry));
+out:
+	return len;
+}
+
+/*
+ * debug_next_entry:
+ * - goto next entry in p_info
+ */
+static inline int debug_next_entry(file_private_info_t *p_info)
+{
+	debug_info_t *id;
+
+	id = p_info->debug_info_snap;
+	if (p_info->act_entry == DEBUG_PROLOG_ENTRY) {
+		p_info->act_entry = 0;
+		p_info->act_page  = 0;
+		goto out;
+	}
+	if (!id->areas)
+		return 1;
+	p_info->act_entry += id->entry_size;
+	/* switch to next page, if we reached the end of the page  */
+	if (p_info->act_entry > (PAGE_SIZE - id->entry_size)) {
+		/* next page */
+		p_info->act_entry = 0;
+		p_info->act_page += 1;
+		if ((p_info->act_page % id->pages_per_area) == 0) {
+			/* next area */
+			p_info->act_area++;
+			p_info->act_page = 0;
+		}
+		if (p_info->act_area >= id->nr_areas)
+			return 1;
+	}
+out:
+	return 0;
+}
+
+/*
+ * debug_output:
+ * - called for user read()
+ * - copies formated debug entries to the user buffer
+ */
+static ssize_t debug_output(struct file *file,		/* file descriptor */
+			    char __user *user_buf,	/* user buffer */
+			    size_t len,			/* length of buffer */
+			    loff_t *offset)		/* offset in the file */
+{
+	size_t count = 0;
+	size_t entry_offset;
+	file_private_info_t *p_info;
+
+	p_info = (file_private_info_t *) file->private_data;
+	if (*offset != p_info->offset)
+		return -EPIPE;
+	if (p_info->act_area >= p_info->debug_info_snap->nr_areas)
+		return 0;
+	entry_offset = p_info->act_entry_offset;
+	while (count < len) {
+		int formatted_line_residue;
+		int formatted_line_size;
+		int user_buf_residue;
+		size_t copy_size;
+
+		formatted_line_size = debug_format_entry(p_info);
+		formatted_line_residue = formatted_line_size - entry_offset;
+		user_buf_residue = len-count;
+		copy_size = min(user_buf_residue, formatted_line_residue);
+		if (copy_size) {
+			if (copy_to_user(user_buf + count, p_info->temp_buf
+					 + entry_offset, copy_size))
+				return -EFAULT;
+			count += copy_size;
+			entry_offset += copy_size;
+		}
+		if (copy_size == formatted_line_residue) {
+			entry_offset = 0;
+			if (debug_next_entry(p_info))
+				goto out;
+		}
+	}
+out:
+	p_info->offset		 = *offset + count;
+	p_info->act_entry_offset = entry_offset;
+	*offset = p_info->offset;
+	return count;
+}
+
+/*
+ * debug_input:
+ * - called for user write()
+ * - calls input function of view
+ */
+static ssize_t debug_input(struct file *file, const char __user *user_buf,
+			   size_t length, loff_t *offset)
+{
+	file_private_info_t *p_info;
+	int rc = 0;
+
+	mutex_lock(&debug_mutex);
+	p_info = ((file_private_info_t *) file->private_data);
+	if (p_info->view->input_proc) {
+		rc = p_info->view->input_proc(p_info->debug_info_org,
+					      p_info->view, file, user_buf,
+					      length, offset);
+	} else {
+		rc = -EPERM;
+	}
+	mutex_unlock(&debug_mutex);
+	return rc; /* number of input characters */
+}
+
+/*
+ * debug_open:
+ * - called for user open()
+ * - copies formated output to private_data area of the file
+ *   handle
+ */
+static int debug_open(struct inode *inode, struct file *file)
+{
+	debug_info_t *debug_info, *debug_info_snapshot;
+	file_private_info_t *p_info;
+	int i, rc = 0;
+
+	mutex_lock(&debug_mutex);
+	debug_info = file_inode(file)->i_private;
+	/* find debug view */
+	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
+		if (!debug_info->views[i])
+			continue;
+		else if (debug_info->debugfs_entries[i] == file->f_path.dentry)
+			goto found; /* found view ! */
+	}
+	/* no entry found */
+	rc = -EINVAL;
+	goto out;
+
+found:
+
+	/* Make snapshot of current debug areas to get it consistent.	  */
+	/* To copy all the areas is only needed, if we have a view which  */
+	/* formats the debug areas. */
+
+	if (!debug_info->views[i]->format_proc && !debug_info->views[i]->header_proc)
+		debug_info_snapshot = debug_info_copy(debug_info, NO_AREAS);
+	else
+		debug_info_snapshot = debug_info_copy(debug_info, ALL_AREAS);
+
+	if (!debug_info_snapshot) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	p_info = kmalloc(sizeof(file_private_info_t), GFP_KERNEL);
+	if (!p_info) {
+		debug_info_free(debug_info_snapshot);
+		rc = -ENOMEM;
+		goto out;
+	}
+	p_info->offset = 0;
+	p_info->debug_info_snap = debug_info_snapshot;
+	p_info->debug_info_org	= debug_info;
+	p_info->view = debug_info->views[i];
+	p_info->act_area = 0;
+	p_info->act_page = 0;
+	p_info->act_entry = DEBUG_PROLOG_ENTRY;
+	p_info->act_entry_offset = 0;
+	file->private_data = p_info;
+	debug_info_get(debug_info);
+	nonseekable_open(inode, file);
+out:
+	mutex_unlock(&debug_mutex);
+	return rc;
+}
+
+/*
+ * debug_close:
+ * - called for user close()
+ * - deletes  private_data area of the file handle
+ */
+static int debug_close(struct inode *inode, struct file *file)
+{
+	file_private_info_t *p_info;
+
+	p_info = (file_private_info_t *) file->private_data;
+	if (p_info->debug_info_snap)
+		debug_info_free(p_info->debug_info_snap);
+	debug_info_put(p_info->debug_info_org);
+	kfree(file->private_data);
+	return 0; /* success */
+}
+
+/* Create debugfs entries and add to internal list. */
+static void _debug_register(debug_info_t *id)
+{
+	/* create root directory */
+	id->debugfs_root_entry = debugfs_create_dir(id->name,
+						    debug_debugfs_root_entry);
+
+	/* append new element to linked list */
+	if (!debug_area_first) {
+		/* first element in list */
+		debug_area_first = id;
+		id->prev = NULL;
+	} else {
+		/* append element to end of list */
+		debug_area_last->next = id;
+		id->prev = debug_area_last;
+	}
+	debug_area_last = id;
+	id->next = NULL;
+
+	debug_register_view(id, &debug_level_view);
+	debug_register_view(id, &debug_flush_view);
+	debug_register_view(id, &debug_pages_view);
+}
+
+/**
+ * debug_register_mode() - creates and initializes debug area.
+ *
+ * @name:	Name of debug log (e.g. used for debugfs entry)
+ * @pages_per_area:	Number of pages, which will be allocated per area
+ * @nr_areas:	Number of debug areas
+ * @buf_size:	Size of data area in each debug entry
+ * @mode:	File mode for debugfs files. E.g. S_IRWXUGO
+ * @uid:	User ID for debugfs files. Currently only 0 is supported.
+ * @gid:	Group ID for debugfs files. Currently only 0 is supported.
+ *
+ * Return:
+ * - Handle for generated debug area
+ * - %NULL if register failed
+ *
+ * Allocates memory for a debug log.
+ * Must not be called within an interrupt handler.
+ */
+debug_info_t *debug_register_mode(const char *name, int pages_per_area,
+				  int nr_areas, int buf_size, umode_t mode,
+				  uid_t uid, gid_t gid)
+{
+	debug_info_t *rc = NULL;
+
+	/* Since debugfs currently does not support uid/gid other than root, */
+	/* we do not allow gid/uid != 0 until we get support for that. */
+	if ((uid != 0) || (gid != 0))
+		pr_warn("Root becomes the owner of all s390dbf files in sysfs\n");
+	BUG_ON(!initialized);
+
+	/* create new debug_info */
+	rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode);
+	if (rc) {
+		mutex_lock(&debug_mutex);
+		_debug_register(rc);
+		mutex_unlock(&debug_mutex);
+	} else {
+		pr_err("Registering debug feature %s failed\n", name);
+	}
+	return rc;
+}
+EXPORT_SYMBOL(debug_register_mode);
+
+/**
+ * debug_register() - creates and initializes debug area with default file mode.
+ *
+ * @name:	Name of debug log (e.g. used for debugfs entry)
+ * @pages_per_area:	Number of pages, which will be allocated per area
+ * @nr_areas:	Number of debug areas
+ * @buf_size:	Size of data area in each debug entry
+ *
+ * Return:
+ * - Handle for generated debug area
+ * - %NULL if register failed
+ *
+ * Allocates memory for a debug log.
+ * The debugfs file mode access permissions are read and write for user.
+ * Must not be called within an interrupt handler.
+ */
+debug_info_t *debug_register(const char *name, int pages_per_area,
+			     int nr_areas, int buf_size)
+{
+	return debug_register_mode(name, pages_per_area, nr_areas, buf_size,
+				   S_IRUSR | S_IWUSR, 0, 0);
+}
+EXPORT_SYMBOL(debug_register);
+
+/**
+ * debug_register_static() - registers a static debug area
+ *
+ * @id: Handle for static debug area
+ * @pages_per_area: Number of pages per area
+ * @nr_areas: Number of debug areas
+ *
+ * Register debug_info_t defined using DEFINE_STATIC_DEBUG_INFO.
+ *
+ * Note: This function is called automatically via an initcall generated by
+ *	 DEFINE_STATIC_DEBUG_INFO.
+ */
+void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas)
+{
+	unsigned long flags;
+	debug_info_t *copy;
+
+	if (!initialized) {
+		pr_err("Tried to register debug feature %s too early\n",
+		       id->name);
+		return;
+	}
+
+	copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
+				id->level, ALL_AREAS);
+	if (!copy) {
+		pr_err("Registering debug feature %s failed\n", id->name);
+
+		/* Clear pointers to prevent tracing into released initdata. */
+		spin_lock_irqsave(&id->lock, flags);
+		id->areas = NULL;
+		id->active_pages = NULL;
+		id->active_entries = NULL;
+		spin_unlock_irqrestore(&id->lock, flags);
+
+		return;
+	}
+
+	/* Replace static trace area with dynamic copy. */
+	spin_lock_irqsave(&id->lock, flags);
+	debug_events_append(copy, id);
+	debug_areas_swap(id, copy);
+	spin_unlock_irqrestore(&id->lock, flags);
+
+	/* Clear pointers to initdata and discard copy. */
+	copy->areas = NULL;
+	copy->active_pages = NULL;
+	copy->active_entries = NULL;
+	debug_info_free(copy);
+
+	mutex_lock(&debug_mutex);
+	_debug_register(id);
+	mutex_unlock(&debug_mutex);
+}
+
+/* Remove debugfs entries and remove from internal list. */
+static void _debug_unregister(debug_info_t *id)
+{
+	int i;
+
+	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
+		if (!id->views[i])
+			continue;
+		debugfs_remove(id->debugfs_entries[i]);
+	}
+	debugfs_remove(id->debugfs_root_entry);
+	if (id == debug_area_first)
+		debug_area_first = id->next;
+	if (id == debug_area_last)
+		debug_area_last = id->prev;
+	if (id->prev)
+		id->prev->next = id->next;
+	if (id->next)
+		id->next->prev = id->prev;
+}
+
+/**
+ * debug_unregister() - give back debug area.
+ *
+ * @id:		handle for debug log
+ *
+ * Return:
+ *    none
+ */
+void debug_unregister(debug_info_t *id)
+{
+	if (!id)
+		return;
+	mutex_lock(&debug_mutex);
+	_debug_unregister(id);
+	mutex_unlock(&debug_mutex);
+
+	debug_info_put(id);
+}
+EXPORT_SYMBOL(debug_unregister);
+
+/*
+ * debug_set_size:
+ * - set area size (number of pages) and number of areas
+ */
+static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)
+{
+	debug_info_t *new_id;
+	unsigned long flags;
+
+	if (!id || (nr_areas <= 0) || (pages_per_area < 0))
+		return -EINVAL;
+
+	new_id = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
+				  id->level, ALL_AREAS);
+	if (!new_id) {
+		pr_info("Allocating memory for %i pages failed\n",
+			pages_per_area);
+		return -ENOMEM;
+	}
+
+	spin_lock_irqsave(&id->lock, flags);
+	debug_events_append(new_id, id);
+	debug_areas_swap(new_id, id);
+	debug_info_free(new_id);
+	spin_unlock_irqrestore(&id->lock, flags);
+	pr_info("%s: set new size (%i pages)\n", id->name, pages_per_area);
+
+	return 0;
+}
+
+/**
+ * debug_set_level() - Sets new actual debug level if new_level is valid.
+ *
+ * @id:		handle for debug log
+ * @new_level:	new debug level
+ *
+ * Return:
+ *    none
+ */
+void debug_set_level(debug_info_t *id, int new_level)
+{
+	unsigned long flags;
+
+	if (!id)
+		return;
+
+	if (new_level == DEBUG_OFF_LEVEL) {
+		pr_info("%s: switched off\n", id->name);
+	} else if ((new_level > DEBUG_MAX_LEVEL) || (new_level < 0)) {
+		pr_info("%s: level %i is out of range (%i - %i)\n",
+			id->name, new_level, 0, DEBUG_MAX_LEVEL);
+		return;
+	}
+
+	spin_lock_irqsave(&id->lock, flags);
+	id->level = new_level;
+	spin_unlock_irqrestore(&id->lock, flags);
+}
+EXPORT_SYMBOL(debug_set_level);
+
+/*
+ * proceed_active_entry:
+ * - set active entry to next in the ring buffer
+ */
+static inline void proceed_active_entry(debug_info_t *id)
+{
+	if ((id->active_entries[id->active_area] += id->entry_size)
+	    > (PAGE_SIZE - id->entry_size)) {
+		id->active_entries[id->active_area] = 0;
+		id->active_pages[id->active_area] =
+			(id->active_pages[id->active_area] + 1) %
+			id->pages_per_area;
+	}
+}
+
+/*
+ * proceed_active_area:
+ * - set active area to next in the ring buffer
+ */
+static inline void proceed_active_area(debug_info_t *id)
+{
+	id->active_area++;
+	id->active_area = id->active_area % id->nr_areas;
+}
+
+/*
+ * get_active_entry:
+ */
+static inline debug_entry_t *get_active_entry(debug_info_t *id)
+{
+	return (debug_entry_t *) (((char *) id->areas[id->active_area]
+				   [id->active_pages[id->active_area]]) +
+				  id->active_entries[id->active_area]);
+}
+
+/* Swap debug areas of a and b. */
+static void debug_areas_swap(debug_info_t *a, debug_info_t *b)
+{
+	swap(a->nr_areas, b->nr_areas);
+	swap(a->pages_per_area, b->pages_per_area);
+	swap(a->areas, b->areas);
+	swap(a->active_area, b->active_area);
+	swap(a->active_pages, b->active_pages);
+	swap(a->active_entries, b->active_entries);
+}
+
+/* Append all debug events in active area from source to destination log. */
+static void debug_events_append(debug_info_t *dest, debug_info_t *src)
+{
+	debug_entry_t *from, *to, *last;
+
+	if (!src->areas || !dest->areas)
+		return;
+
+	/* Loop over all entries in src, starting with oldest. */
+	from = get_active_entry(src);
+	last = from;
+	do {
+		if (from->clock != 0LL) {
+			to = get_active_entry(dest);
+			memset(to, 0, dest->entry_size);
+			memcpy(to, from, min(src->entry_size,
+					     dest->entry_size));
+			proceed_active_entry(dest);
+		}
+
+		proceed_active_entry(src);
+		from = get_active_entry(src);
+	} while (from != last);
+}
+
+/*
+ * debug_finish_entry:
+ * - set timestamp, caller address, cpu number etc.
+ */
+
+static inline void debug_finish_entry(debug_info_t *id, debug_entry_t *active,
+				      int level, int exception)
+{
+	unsigned long timestamp;
+	union tod_clock clk;
+
+	store_tod_clock_ext(&clk);
+	timestamp = clk.us;
+	timestamp -= TOD_UNIX_EPOCH >> 12;
+	active->clock = timestamp;
+	active->cpu = smp_processor_id();
+	active->caller = __builtin_return_address(0);
+	active->exception = exception;
+	active->level = level;
+	proceed_active_entry(id);
+	if (exception)
+		proceed_active_area(id);
+}
+
+static int debug_stoppable = 1;
+static int debug_active = 1;
+
+#define CTL_S390DBF_STOPPABLE 5678
+#define CTL_S390DBF_ACTIVE 5679
+
+/*
+ * proc handler for the running debug_active sysctl
+ * always allow read, allow write only if debug_stoppable is set or
+ * if debug_active is already off
+ */
+static int s390dbf_procactive(struct ctl_table *table, int write,
+			      void *buffer, size_t *lenp, loff_t *ppos)
+{
+	if (!write || debug_stoppable || !debug_active)
+		return proc_dointvec(table, write, buffer, lenp, ppos);
+	else
+		return 0;
+}
+
+static struct ctl_table s390dbf_table[] = {
+	{
+		.procname	= "debug_stoppable",
+		.data		= &debug_stoppable,
+		.maxlen		= sizeof(int),
+		.mode		= S_IRUGO | S_IWUSR,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "debug_active",
+		.data		= &debug_active,
+		.maxlen		= sizeof(int),
+		.mode		= S_IRUGO | S_IWUSR,
+		.proc_handler	= s390dbf_procactive,
+	},
+	{ }
+};
+
+static struct ctl_table s390dbf_dir_table[] = {
+	{
+		.procname	= "s390dbf",
+		.maxlen		= 0,
+		.mode		= S_IRUGO | S_IXUGO,
+		.child		= s390dbf_table,
+	},
+	{ }
+};
+
+static struct ctl_table_header *s390dbf_sysctl_header;
+
+/**
+ * debug_stop_all() - stops the debug feature if stopping is allowed.
+ *
+ * Return:
+ * -   none
+ *
+ * Currently used in case of a kernel oops.
+ */
+void debug_stop_all(void)
+{
+	if (debug_stoppable)
+		debug_active = 0;
+}
+EXPORT_SYMBOL(debug_stop_all);
+
+/**
+ * debug_set_critical() - event/exception functions try lock instead of spin.
+ *
+ * Return:
+ * -   none
+ *
+ * Currently used in case of stopping all CPUs but the current one.
+ * Once in this state, functions to write a debug entry for an
+ * event or exception no longer spin on the debug area lock,
+ * but only try to get it and fail if they do not get the lock.
+ */
+void debug_set_critical(void)
+{
+	debug_critical = 1;
+}
+
+/*
+ * debug_event_common:
+ * - write debug entry with given size
+ */
+debug_entry_t *debug_event_common(debug_info_t *id, int level, const void *buf,
+				  int len)
+{
+	debug_entry_t *active;
+	unsigned long flags;
+
+	if (!debug_active || !id->areas)
+		return NULL;
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else {
+		spin_lock_irqsave(&id->lock, flags);
+	}
+	do {
+		active = get_active_entry(id);
+		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
+		if (len < id->buf_size)
+			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
+		debug_finish_entry(id, active, level, 0);
+		len -= id->buf_size;
+		buf += id->buf_size;
+	} while (len > 0);
+
+	spin_unlock_irqrestore(&id->lock, flags);
+	return active;
+}
+EXPORT_SYMBOL(debug_event_common);
+
+/*
+ * debug_exception_common:
+ * - write debug entry with given size and switch to next debug area
+ */
+debug_entry_t *debug_exception_common(debug_info_t *id, int level,
+				      const void *buf, int len)
+{
+	debug_entry_t *active;
+	unsigned long flags;
+
+	if (!debug_active || !id->areas)
+		return NULL;
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else {
+		spin_lock_irqsave(&id->lock, flags);
+	}
+	do {
+		active = get_active_entry(id);
+		memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
+		if (len < id->buf_size)
+			memset((DEBUG_DATA(active)) + len, 0, id->buf_size - len);
+		debug_finish_entry(id, active, level, len <= id->buf_size);
+		len -= id->buf_size;
+		buf += id->buf_size;
+	} while (len > 0);
+
+	spin_unlock_irqrestore(&id->lock, flags);
+	return active;
+}
+EXPORT_SYMBOL(debug_exception_common);
+
+/*
+ * counts arguments in format string for sprintf view
+ */
+static inline int debug_count_numargs(char *string)
+{
+	int numargs = 0;
+
+	while (*string) {
+		if (*string++ == '%')
+			numargs++;
+	}
+	return numargs;
+}
+
+/*
+ * debug_sprintf_event:
+ */
+debug_entry_t *__debug_sprintf_event(debug_info_t *id, int level, char *string, ...)
+{
+	debug_sprintf_entry_t *curr_event;
+	debug_entry_t *active;
+	unsigned long flags;
+	int numargs, idx;
+	va_list ap;
+
+	if (!debug_active || !id->areas)
+		return NULL;
+	numargs = debug_count_numargs(string);
+
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else {
+		spin_lock_irqsave(&id->lock, flags);
+	}
+	active = get_active_entry(id);
+	curr_event = (debug_sprintf_entry_t *) DEBUG_DATA(active);
+	va_start(ap, string);
+	curr_event->string = string;
+	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
+		curr_event->args[idx] = va_arg(ap, long);
+	va_end(ap);
+	debug_finish_entry(id, active, level, 0);
+	spin_unlock_irqrestore(&id->lock, flags);
+
+	return active;
+}
+EXPORT_SYMBOL(__debug_sprintf_event);
+
+/*
+ * debug_sprintf_exception:
+ */
+debug_entry_t *__debug_sprintf_exception(debug_info_t *id, int level, char *string, ...)
+{
+	debug_sprintf_entry_t *curr_event;
+	debug_entry_t *active;
+	unsigned long flags;
+	int numargs, idx;
+	va_list ap;
+
+	if (!debug_active || !id->areas)
+		return NULL;
+
+	numargs = debug_count_numargs(string);
+
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else {
+		spin_lock_irqsave(&id->lock, flags);
+	}
+	active = get_active_entry(id);
+	curr_event = (debug_sprintf_entry_t *)DEBUG_DATA(active);
+	va_start(ap, string);
+	curr_event->string = string;
+	for (idx = 0; idx < min(numargs, (int)(id->buf_size / sizeof(long)) - 1); idx++)
+		curr_event->args[idx] = va_arg(ap, long);
+	va_end(ap);
+	debug_finish_entry(id, active, level, 1);
+	spin_unlock_irqrestore(&id->lock, flags);
+
+	return active;
+}
+EXPORT_SYMBOL(__debug_sprintf_exception);
+
+/**
+ * debug_register_view() - registers new debug view and creates debugfs
+ *			   dir entry
+ *
+ * @id:		handle for debug log
+ * @view:	pointer to debug view struct
+ *
+ * Return:
+ * -   0  : ok
+ * -   < 0: Error
+ */
+int debug_register_view(debug_info_t *id, struct debug_view *view)
+{
+	unsigned long flags;
+	struct dentry *pde;
+	umode_t mode;
+	int rc = 0;
+	int i;
+
+	if (!id)
+		goto out;
+	mode = (id->mode | S_IFREG) & ~S_IXUGO;
+	if (!(view->prolog_proc || view->format_proc || view->header_proc))
+		mode &= ~(S_IRUSR | S_IRGRP | S_IROTH);
+	if (!view->input_proc)
+		mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
+	pde = debugfs_create_file(view->name, mode, id->debugfs_root_entry,
+				  id, &debug_file_ops);
+	spin_lock_irqsave(&id->lock, flags);
+	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
+		if (!id->views[i])
+			break;
+	}
+	if (i == DEBUG_MAX_VIEWS) {
+		rc = -1;
+	} else {
+		id->views[i] = view;
+		id->debugfs_entries[i] = pde;
+	}
+	spin_unlock_irqrestore(&id->lock, flags);
+	if (rc) {
+		pr_err("Registering view %s/%s would exceed the maximum "
+		       "number of views %i\n", id->name, view->name, i);
+		debugfs_remove(pde);
+	}
+out:
+	return rc;
+}
+EXPORT_SYMBOL(debug_register_view);
+
+/**
+ * debug_unregister_view() - unregisters debug view and removes debugfs
+ *			     dir entry
+ *
+ * @id:		handle for debug log
+ * @view:	pointer to debug view struct
+ *
+ * Return:
+ * -   0  : ok
+ * -   < 0: Error
+ */
+int debug_unregister_view(debug_info_t *id, struct debug_view *view)
+{
+	struct dentry *dentry = NULL;
+	unsigned long flags;
+	int i, rc = 0;
+
+	if (!id)
+		goto out;
+	spin_lock_irqsave(&id->lock, flags);
+	for (i = 0; i < DEBUG_MAX_VIEWS; i++) {
+		if (id->views[i] == view)
+			break;
+	}
+	if (i == DEBUG_MAX_VIEWS) {
+		rc = -1;
+	} else {
+		dentry = id->debugfs_entries[i];
+		id->views[i] = NULL;
+		id->debugfs_entries[i] = NULL;
+	}
+	spin_unlock_irqrestore(&id->lock, flags);
+	debugfs_remove(dentry);
+out:
+	return rc;
+}
+EXPORT_SYMBOL(debug_unregister_view);
+
+static inline char *debug_get_user_string(const char __user *user_buf,
+					  size_t user_len)
+{
+	char *buffer;
+
+	buffer = kmalloc(user_len + 1, GFP_KERNEL);
+	if (!buffer)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_user(buffer, user_buf, user_len) != 0) {
+		kfree(buffer);
+		return ERR_PTR(-EFAULT);
+	}
+	/* got the string, now strip linefeed. */
+	if (buffer[user_len - 1] == '\n')
+		buffer[user_len - 1] = 0;
+	else
+		buffer[user_len] = 0;
+	return buffer;
+}
+
+static inline int debug_get_uint(char *buf)
+{
+	int rc;
+
+	buf = skip_spaces(buf);
+	rc = simple_strtoul(buf, &buf, 10);
+	if (*buf)
+		rc = -EINVAL;
+	return rc;
+}
+
+/*
+ * functions for debug-views
+ ***********************************
+*/
+
+/*
+ * prints out actual debug level
+ */
+
+static int debug_prolog_pages_fn(debug_info_t *id, struct debug_view *view,
+				 char *out_buf)
+{
+	return sprintf(out_buf, "%i\n", id->pages_per_area);
+}
+
+/*
+ * reads new size (number of pages per debug area)
+ */
+
+static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_len, loff_t *offset)
+{
+	int rc, new_pages;
+	char *str;
+
+	if (user_len > 0x10000)
+		user_len = 0x10000;
+	if (*offset != 0) {
+		rc = -EPIPE;
+		goto out;
+	}
+	str = debug_get_user_string(user_buf, user_len);
+	if (IS_ERR(str)) {
+		rc = PTR_ERR(str);
+		goto out;
+	}
+	new_pages = debug_get_uint(str);
+	if (new_pages < 0) {
+		rc = -EINVAL;
+		goto free_str;
+	}
+	rc = debug_set_size(id, id->nr_areas, new_pages);
+	if (rc != 0) {
+		rc = -EINVAL;
+		goto free_str;
+	}
+	rc = user_len;
+free_str:
+	kfree(str);
+out:
+	*offset += user_len;
+	return rc;		/* number of input characters */
+}
+
+/*
+ * prints out actual debug level
+ */
+static int debug_prolog_level_fn(debug_info_t *id, struct debug_view *view,
+				 char *out_buf)
+{
+	int rc = 0;
+
+	if (id->level == DEBUG_OFF_LEVEL)
+		rc = sprintf(out_buf, "-\n");
+	else
+		rc = sprintf(out_buf, "%i\n", id->level);
+	return rc;
+}
+
+/*
+ * reads new debug level
+ */
+static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_len, loff_t *offset)
+{
+	int rc, new_level;
+	char *str;
+
+	if (user_len > 0x10000)
+		user_len = 0x10000;
+	if (*offset != 0) {
+		rc = -EPIPE;
+		goto out;
+	}
+	str = debug_get_user_string(user_buf, user_len);
+	if (IS_ERR(str)) {
+		rc = PTR_ERR(str);
+		goto out;
+	}
+	if (str[0] == '-') {
+		debug_set_level(id, DEBUG_OFF_LEVEL);
+		rc = user_len;
+		goto free_str;
+	} else {
+		new_level = debug_get_uint(str);
+	}
+	if (new_level < 0) {
+		pr_warn("%s is not a valid level for a debug feature\n", str);
+		rc = -EINVAL;
+	} else {
+		debug_set_level(id, new_level);
+		rc = user_len;
+	}
+free_str:
+	kfree(str);
+out:
+	*offset += user_len;
+	return rc;		/* number of input characters */
+}
+
+/*
+ * flushes debug areas
+ */
+static void debug_flush(debug_info_t *id, int area)
+{
+	unsigned long flags;
+	int i, j;
+
+	if (!id || !id->areas)
+		return;
+	spin_lock_irqsave(&id->lock, flags);
+	if (area == DEBUG_FLUSH_ALL) {
+		id->active_area = 0;
+		memset(id->active_entries, 0, id->nr_areas * sizeof(int));
+		for (i = 0; i < id->nr_areas; i++) {
+			id->active_pages[i] = 0;
+			for (j = 0; j < id->pages_per_area; j++)
+				memset(id->areas[i][j], 0, PAGE_SIZE);
+		}
+	} else if (area >= 0 && area < id->nr_areas) {
+		id->active_entries[area] = 0;
+		id->active_pages[area] = 0;
+		for (i = 0; i < id->pages_per_area; i++)
+			memset(id->areas[area][i], 0, PAGE_SIZE);
+	}
+	spin_unlock_irqrestore(&id->lock, flags);
+}
+
+/*
+ * view function: flushes debug areas
+ */
+static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
+				struct file *file, const char __user *user_buf,
+				size_t user_len, loff_t *offset)
+{
+	char input_buf[1];
+	int rc = user_len;
+
+	if (user_len > 0x10000)
+		user_len = 0x10000;
+	if (*offset != 0) {
+		rc = -EPIPE;
+		goto out;
+	}
+	if (copy_from_user(input_buf, user_buf, 1)) {
+		rc = -EFAULT;
+		goto out;
+	}
+	if (input_buf[0] == '-') {
+		debug_flush(id, DEBUG_FLUSH_ALL);
+		goto out;
+	}
+	if (isdigit(input_buf[0])) {
+		int area = ((int) input_buf[0] - (int) '0');
+
+		debug_flush(id, area);
+		goto out;
+	}
+
+	pr_info("Flushing debug data failed because %c is not a valid "
+		 "area\n", input_buf[0]);
+
+out:
+	*offset += user_len;
+	return rc;		/* number of input characters */
+}
+
+/*
+ * prints debug data in hex/ascii format
+ */
+static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
+				     char *out_buf, const char *in_buf)
+{
+	int i, rc = 0;
+
+	for (i = 0; i < id->buf_size; i++)
+		rc += sprintf(out_buf + rc, "%02x ", ((unsigned char *) in_buf)[i]);
+	rc += sprintf(out_buf + rc, "| ");
+	for (i = 0; i < id->buf_size; i++) {
+		unsigned char c = in_buf[i];
+
+		if (isascii(c) && isprint(c))
+			rc += sprintf(out_buf + rc, "%c", c);
+		else
+			rc += sprintf(out_buf + rc, ".");
+	}
+	rc += sprintf(out_buf + rc, "\n");
+	return rc;
+}
+
+/*
+ * prints header for debug entry
+ */
+int debug_dflt_header_fn(debug_info_t *id, struct debug_view *view,
+			 int area, debug_entry_t *entry, char *out_buf)
+{
+	unsigned long sec, usec;
+	unsigned long caller;
+	unsigned int level;
+	char *except_str;
+	int rc = 0;
+
+	level = entry->level;
+	sec = entry->clock;
+	usec = do_div(sec, USEC_PER_SEC);
+
+	if (entry->exception)
+		except_str = "*";
+	else
+		except_str = "-";
+	caller = (unsigned long) entry->caller;
+	rc += sprintf(out_buf, "%02i %011ld:%06lu %1u %1s %04u %px  ",
+		      area, sec, usec, level, except_str,
+		      entry->cpu, (void *)caller);
+	return rc;
+}
+EXPORT_SYMBOL(debug_dflt_header_fn);
+
+/*
+ * prints debug data sprintf-formated:
+ * debug_sprinf_event/exception calls must be used together with this view
+ */
+
+#define DEBUG_SPRINTF_MAX_ARGS 10
+
+static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
+				   char *out_buf, debug_sprintf_entry_t *curr_event)
+{
+	int num_longs, num_used_args = 0, i, rc = 0;
+	int index[DEBUG_SPRINTF_MAX_ARGS];
+
+	/* count of longs fit into one entry */
+	num_longs = id->buf_size / sizeof(long);
+
+	if (num_longs < 1)
+		goto out; /* bufsize of entry too small */
+	if (num_longs == 1) {
+		/* no args, we use only the string */
+		strcpy(out_buf, curr_event->string);
+		rc = strlen(curr_event->string);
+		goto out;
+	}
+
+	/* number of arguments used for sprintf (without the format string) */
+	num_used_args = min(DEBUG_SPRINTF_MAX_ARGS, (num_longs - 1));
+
+	memset(index, 0, DEBUG_SPRINTF_MAX_ARGS * sizeof(int));
+
+	for (i = 0; i < num_used_args; i++)
+		index[i] = i;
+
+	rc = sprintf(out_buf, curr_event->string, curr_event->args[index[0]],
+		     curr_event->args[index[1]], curr_event->args[index[2]],
+		     curr_event->args[index[3]], curr_event->args[index[4]],
+		     curr_event->args[index[5]], curr_event->args[index[6]],
+		     curr_event->args[index[7]], curr_event->args[index[8]],
+		     curr_event->args[index[9]]);
+out:
+	return rc;
+}
+
+/*
+ * debug_init:
+ * - is called exactly once to initialize the debug feature
+ */
+static int __init debug_init(void)
+{
+	s390dbf_sysctl_header = register_sysctl_table(s390dbf_dir_table);
+	mutex_lock(&debug_mutex);
+	debug_debugfs_root_entry = debugfs_create_dir(DEBUG_DIR_ROOT, NULL);
+	initialized = 1;
+	mutex_unlock(&debug_mutex);
+	return 0;
+}
+postcore_initcall(debug_init);