Commit 12047778 authored by Peter Oberparleiter's avatar Peter Oberparleiter Committed by Heiko Carstens
Browse files

s390/debug: keep debug data on resize 



Any previously recorded s390dbf debug data is reset when a debug area
is resized using the 'pages' sysfs attribute. This can make
live-debugging unnecessarily complex.

Fix this by copying existing debug data to the newly allocated debug
area when resizing.

Signed-off-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 2879048c

arch/s390/kernel/debug.c

+53 −21
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/export.h>

#include <linux/init.h>

#include <linux/fs.h>

#include <linux/minmax.h>

#include <linux/debugfs.h>



#include <asm/debug.h>
@@ -92,6 +93,8 @@ 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 */
@@ -726,35 +729,28 @@ EXPORT_SYMBOL(debug_unregister); 
 */

static int debug_set_size(debug_info_t *id, int nr_areas, int pages_per_area)

{

	debug_entry_t ***new_areas;

	debug_info_t *new_id;

	unsigned long flags;

	int rc = 0;



	if (!id || (nr_areas <= 0) || (pages_per_area < 0))

		return -EINVAL;

	if (pages_per_area > 0) {

		new_areas = debug_areas_alloc(pages_per_area, nr_areas);

		if (!new_areas) {



	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);

			rc = -ENOMEM;

			goto out;

		}

	} else {

		new_areas = NULL;

		return -ENOMEM;

	}



	spin_lock_irqsave(&id->lock, flags);

	debug_areas_free(id);

	id->areas = new_areas;

	id->nr_areas = nr_areas;

	id->pages_per_area = pages_per_area;

	id->active_area = 0;

	memset(id->active_entries, 0, sizeof(int)*id->nr_areas);

	memset(id->active_pages, 0, sizeof(int)*id->nr_areas);

	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);

out:

	return rc;



	return 0;

}



/**
@@ -821,6 +817,42 @@ static inline debug_entry_t *get_active_entry(debug_info_t *id) 
				  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.