s390/debug: add early tracing support
Debug areas can currently only be used after s390dbf initialization
which occurs as a postcore_initcall. This is too late for tracing
earlier code such as that related to console_init().
This patch introduces a macro for defining a statically initialized
debug area that can be used to trace very early code. The macro is made
available for built-in code only because modules are never running
during early boot.
Example usage:
1. Define static debug area:
DEFINE_STATIC_DEBUG_INFO(my_debug, "my_debug", 4, 1, 16,
&debug_hex_ascii_view);
2. Add trace entry:
debug_event(&my_debug, 0, "DATA", 4);
Note: The debug area is automatically registered in debugfs during boot.
A driver must not call any of the debug_register()/_unregister()
functions on a static debug_info_t!
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Peter Oberparleiter
Heiko Carstens
parent
9372a82892
commit
d72541f945
@ -13,6 +13,7 @@
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#include <linux/time.h>
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#include <linux/refcount.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#define DEBUG_MAX_LEVEL 6 /* debug levels range from 0 to 6 */
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#define DEBUG_OFF_LEVEL -1 /* level where debug is switched off */
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@ -391,4 +392,99 @@ int debug_register_view(debug_info_t *id, struct debug_view *view);
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int debug_unregister_view(debug_info_t *id, struct debug_view *view);
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#ifndef MODULE
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/*
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* Note: Initial page and area numbers must be fixed to allow static
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* initialization. This enables very early tracing. Changes to these values
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* must be reflected in __DEFINE_STATIC_AREA.
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*/
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#define EARLY_PAGES 8
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#define EARLY_AREAS 1
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#define VNAME(var, suffix) __##var##_##suffix
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/*
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* Define static areas for early trace data. During boot debug_register_static()
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* will replace these with dynamically allocated areas to allow custom page and
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* area sizes, and dynamic resizing.
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*/
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#define __DEFINE_STATIC_AREA(var) \
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static char VNAME(var, data)[EARLY_PAGES][PAGE_SIZE] __initdata; \
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static debug_entry_t *VNAME(var, pages)[EARLY_PAGES] __initdata = { \
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(debug_entry_t *)VNAME(var, data)[0], \
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(debug_entry_t *)VNAME(var, data)[1], \
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(debug_entry_t *)VNAME(var, data)[2], \
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(debug_entry_t *)VNAME(var, data)[3], \
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(debug_entry_t *)VNAME(var, data)[4], \
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(debug_entry_t *)VNAME(var, data)[5], \
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(debug_entry_t *)VNAME(var, data)[6], \
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(debug_entry_t *)VNAME(var, data)[7], \
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}; \
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static debug_entry_t **VNAME(var, areas)[EARLY_AREAS] __initdata = { \
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(debug_entry_t **)VNAME(var, pages), \
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}; \
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static int VNAME(var, active_pages)[EARLY_AREAS] __initdata; \
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static int VNAME(var, active_entries)[EARLY_AREAS] __initdata
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#define __DEBUG_INFO_INIT(var, _name, _buf_size) { \
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.next = NULL, \
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.prev = NULL, \
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.ref_count = REFCOUNT_INIT(1), \
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.lock = __SPIN_LOCK_UNLOCKED(var.lock), \
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.level = DEBUG_DEFAULT_LEVEL, \
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.nr_areas = EARLY_AREAS, \
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.pages_per_area = EARLY_PAGES, \
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.buf_size = (_buf_size), \
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.entry_size = sizeof(debug_entry_t) + (_buf_size), \
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.areas = VNAME(var, areas), \
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.active_area = 0, \
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.active_pages = VNAME(var, active_pages), \
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.active_entries = VNAME(var, active_entries), \
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.debugfs_root_entry = NULL, \
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.debugfs_entries = { NULL }, \
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.views = { NULL }, \
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.name = (_name), \
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.mode = 0600, \
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}
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#define __REGISTER_STATIC_DEBUG_INFO(var, name, pages, areas, view) \
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static int __init VNAME(var, reg)(void) \
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{ \
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debug_register_static(&var, (pages), (areas)); \
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debug_register_view(&var, (view)); \
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return 0; \
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} \
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arch_initcall(VNAME(var, reg))
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/**
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* DEFINE_STATIC_DEBUG_INFO - Define static debug_info_t
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*
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* @var: Name of debug_info_t variable
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* @name: Name of debug log (e.g. used for debugfs entry)
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* @pages_per_area: Number of pages per area
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* @nr_areas: Number of debug areas
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* @buf_size: Size of data area in each debug entry
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* @view: Pointer to debug view struct
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*
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* Define a static debug_info_t for early tracing. The associated debugfs log
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* is automatically registered with the specified debug view.
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*
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* Important: Users of this macro must not call any of the
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* debug_register/_unregister() functions for this debug_info_t!
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*
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* Note: Tracing will start with a fixed number of initial pages and areas.
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* The debug area will be changed to use the specified numbers during
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* arch_initcall.
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*/
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#define DEFINE_STATIC_DEBUG_INFO(var, name, pages, nr_areas, buf_size, view) \
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__DEFINE_STATIC_AREA(var); \
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static debug_info_t __refdata var = \
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__DEBUG_INFO_INIT(var, (name), (buf_size)); \
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__REGISTER_STATIC_DEBUG_INFO(var, name, pages, nr_areas, view)
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void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas);
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#endif /* MODULE */
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#endif /* DEBUG_H */
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@ -692,6 +692,61 @@ debug_info_t *debug_register(const char *name, int pages_per_area,
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}
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EXPORT_SYMBOL(debug_register);
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/**
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* debug_register_static() - registers a static debug area
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*
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* @id: Handle for static debug area
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* @pages_per_area: Number of pages per area
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* @nr_areas: Number of debug areas
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*
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* Register debug_info_t defined using DEFINE_STATIC_DEBUG_INFO.
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*
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* Note: This function is called automatically via an initcall generated by
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* DEFINE_STATIC_DEBUG_INFO.
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*/
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void debug_register_static(debug_info_t *id, int pages_per_area, int nr_areas)
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{
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unsigned long flags;
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debug_info_t *copy;
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if (!initialized) {
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pr_err("Tried to register debug feature %s too early\n",
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id->name);
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return;
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}
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copy = debug_info_alloc("", pages_per_area, nr_areas, id->buf_size,
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id->level, ALL_AREAS);
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if (!copy) {
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pr_err("Registering debug feature %s failed\n", id->name);
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/* Clear pointers to prevent tracing into released initdata. */
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spin_lock_irqsave(&id->lock, flags);
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id->areas = NULL;
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id->active_pages = NULL;
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id->active_entries = NULL;
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spin_unlock_irqrestore(&id->lock, flags);
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return;
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}
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/* Replace static trace area with dynamic copy. */
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spin_lock_irqsave(&id->lock, flags);
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debug_events_append(copy, id);
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debug_areas_swap(id, copy);
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spin_unlock_irqrestore(&id->lock, flags);
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/* Clear pointers to initdata and discard copy. */
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copy->areas = NULL;
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copy->active_pages = NULL;
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copy->active_entries = NULL;
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debug_info_free(copy);
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mutex_lock(&debug_mutex);
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_debug_register(id);
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mutex_unlock(&debug_mutex);
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}
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/* Remove debugfs entries and remove from internal list. */
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static void _debug_unregister(debug_info_t *id)
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{
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