linux/kernel/gcov/base.c
Andrey Ryabinin 9d796e6623 gcov: fix softlockups
gcov profiling if enabled with other heavy compile-time instrumentation
like KASan could trigger following softlockups:

  NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]
  Modules linked in:
  irq event stamp: 22823276
  hardirqs last  enabled at (22823275): [<ffffffff86e8d10d>] mutex_lock_nested+0x7d9/0x930
  hardirqs last disabled at (22823276): [<ffffffff86e9521d>] apic_timer_interrupt+0x6d/0x80
  softirqs last  enabled at (22823172): [<ffffffff811ed969>] __do_softirq+0x4db/0x729
  softirqs last disabled at (22823167): [<ffffffff811edfcf>] irq_exit+0x7d/0x15b
  CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W       3.19.0-05245-gbb33326-dirty #3
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
  task: ffff88006cba8000 ti: ffff88006cbb0000 task.ti: ffff88006cbb0000
  RIP: kasan_mem_to_shadow+0x1e/0x1f
  Call Trace:
    strcmp+0x28/0x70
    get_node_by_name+0x66/0x99
    gcov_event+0x4f/0x69e
    gcov_enable_events+0x54/0x7b
    gcov_fs_init+0xf8/0x134
    do_one_initcall+0x1b2/0x288
    kernel_init_freeable+0x467/0x580
    kernel_init+0x15/0x18b
    ret_from_fork+0x7c/0xb0
  Kernel panic - not syncing: softlockup: hung tasks

Fix this by sticking cond_resched() in gcov_enable_events().

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-17 09:04:08 -04:00

162 lines
3.8 KiB
C

/*
* This code maintains a list of active profiling data structures.
*
* Copyright IBM Corp. 2009
* Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
*
* Uses gcc-internal data definitions.
* Based on the gcov-kernel patch by:
* Hubertus Franke <frankeh@us.ibm.com>
* Nigel Hinds <nhinds@us.ibm.com>
* Rajan Ravindran <rajancr@us.ibm.com>
* Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
* Paul Larson
*/
#define pr_fmt(fmt) "gcov: " fmt
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include "gcov.h"
static int gcov_events_enabled;
static DEFINE_MUTEX(gcov_lock);
/*
* __gcov_init is called by gcc-generated constructor code for each object
* file compiled with -fprofile-arcs.
*/
void __gcov_init(struct gcov_info *info)
{
static unsigned int gcov_version;
mutex_lock(&gcov_lock);
if (gcov_version == 0) {
gcov_version = gcov_info_version(info);
/*
* Printing gcc's version magic may prove useful for debugging
* incompatibility reports.
*/
pr_info("version magic: 0x%x\n", gcov_version);
}
/*
* Add new profiling data structure to list and inform event
* listener.
*/
gcov_info_link(info);
if (gcov_events_enabled)
gcov_event(GCOV_ADD, info);
mutex_unlock(&gcov_lock);
}
EXPORT_SYMBOL(__gcov_init);
/*
* These functions may be referenced by gcc-generated profiling code but serve
* no function for kernel profiling.
*/
void __gcov_flush(void)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_flush);
void __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_add);
void __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_single);
void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_delta);
void __gcov_merge_ior(gcov_type *counters, unsigned int n_counters)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_ior);
void __gcov_merge_time_profile(gcov_type *counters, unsigned int n_counters)
{
/* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_time_profile);
/**
* gcov_enable_events - enable event reporting through gcov_event()
*
* Turn on reporting of profiling data load/unload-events through the
* gcov_event() callback. Also replay all previous events once. This function
* is needed because some events are potentially generated too early for the
* callback implementation to handle them initially.
*/
void gcov_enable_events(void)
{
struct gcov_info *info = NULL;
mutex_lock(&gcov_lock);
gcov_events_enabled = 1;
/* Perform event callback for previously registered entries. */
while ((info = gcov_info_next(info))) {
gcov_event(GCOV_ADD, info);
cond_resched();
}
mutex_unlock(&gcov_lock);
}
#ifdef CONFIG_MODULES
static inline int within(void *addr, void *start, unsigned long size)
{
return ((addr >= start) && (addr < start + size));
}
/* Update list and generate events when modules are unloaded. */
static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
void *data)
{
struct module *mod = data;
struct gcov_info *info = NULL;
struct gcov_info *prev = NULL;
if (event != MODULE_STATE_GOING)
return NOTIFY_OK;
mutex_lock(&gcov_lock);
/* Remove entries located in module from linked list. */
while ((info = gcov_info_next(info))) {
if (within(info, mod->module_core, mod->core_size)) {
gcov_info_unlink(prev, info);
if (gcov_events_enabled)
gcov_event(GCOV_REMOVE, info);
} else
prev = info;
}
mutex_unlock(&gcov_lock);
return NOTIFY_OK;
}
static struct notifier_block gcov_nb = {
.notifier_call = gcov_module_notifier,
};
static int __init gcov_init(void)
{
return register_module_notifier(&gcov_nb);
}
device_initcall(gcov_init);
#endif /* CONFIG_MODULES */