From: Peter Oberparleiter oberpar@linux.ibm.com
[ Upstream commit 1204777867e8486a88dbb4793fe256b31ea05eeb ]
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: Peter Oberparleiter oberpar@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kernel/debug.c | 74 ++++++++++++++++++++++++++++------------ 1 file changed, 53 insertions(+), 21 deletions(-)
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index b6619ae9a3e0..e392d3e42b1d 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -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) { - pr_info("Allocating memory for %i pages failed\n", - pages_per_area); - rc = -ENOMEM; - goto out; - } - } else { - new_areas = NULL; + + 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_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.