[linux.git] / kernel / profile.c

/*
 *  linux/kernel/profile.c
 *  Simple profiling. Manages a direct-mapped profile hit count buffer,
 *  with configurable resolution, support for restricting the cpus on
 *  which profiling is done, and switching between cpu time and
 *  schedule() calls via kernel command line parameters passed at boot.
 *
 *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
 *	Red Hat, July 2004
 *  Consolidation of architecture support code for profiling,
 *	William Irwin, Oracle, July 2004
 *  Amortized hit count accounting via per-cpu open-addressed hashtables
 *	to resolve timer interrupt livelocks, William Irwin, Oracle, 2004
 */

#include <linux/module.h>
#include <linux/profile.h>
#include <linux/bootmem.h>
#include <linux/notifier.h>
#include <linux/mm.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/profile.h>
#include <linux/highmem.h>
#include <linux/mutex.h>
#include <asm/sections.h>
#include <asm/semaphore.h>

struct profile_hit {
	u32 pc, hits;
};
#define PROFILE_GRPSHIFT	3
#define PROFILE_GRPSZ		(1 << PROFILE_GRPSHIFT)
#define NR_PROFILE_HIT		(PAGE_SIZE/sizeof(struct profile_hit))
#define NR_PROFILE_GRP		(NR_PROFILE_HIT/PROFILE_GRPSZ)

/* Oprofile timer tick hook */
int (*timer_hook)(struct pt_regs *) __read_mostly;

static atomic_t *prof_buffer;
static unsigned long prof_len, prof_shift;
static int prof_on __read_mostly;
static cpumask_t prof_cpu_mask = CPU_MASK_ALL;
#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
static DEFINE_PER_CPU(int, cpu_profile_flip);
static DEFINE_MUTEX(profile_flip_mutex);
#endif /* CONFIG_SMP */

static int __init profile_setup(char * str)
{
	static char __initdata schedstr[] = "schedule";
	int par;

	if (!strncmp(str, schedstr, strlen(schedstr))) {
		prof_on = SCHED_PROFILING;
		if (str[strlen(schedstr)] == ',')
			str += strlen(schedstr) + 1;
		if (get_option(&str, &par))
			prof_shift = par;
		printk(KERN_INFO
			"kernel schedule profiling enabled (shift: %ld)\n",
			prof_shift);
	} else if (get_option(&str, &par)) {
		prof_shift = par;
		prof_on = CPU_PROFILING;
		printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
			prof_shift);
	}
	return 1;
}
__setup("profile=", profile_setup);


void __init profile_init(void)
{
	if (!prof_on) 
		return;
 
	/* only text is profiled */
	prof_len = (_etext - _stext) >> prof_shift;
	prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));
}

/* Profile event notifications */
 
#ifdef CONFIG_PROFILING
 
static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
 
void profile_task_exit(struct task_struct * task)
{
	blocking_notifier_call_chain(&task_exit_notifier, 0, task);
}
 
int profile_handoff_task(struct task_struct * task)
{
	int ret;
	ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
	return (ret == NOTIFY_OK) ? 1 : 0;
}

void profile_munmap(unsigned long addr)
{
	blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
}

int task_handoff_register(struct notifier_block * n)
{
	return atomic_notifier_chain_register(&task_free_notifier, n);
}

int task_handoff_unregister(struct notifier_block * n)
{
	return atomic_notifier_chain_unregister(&task_free_notifier, n);
}

int profile_event_register(enum profile_type type, struct notifier_block * n)
{
	int err = -EINVAL;
 
	switch (type) {
		case PROFILE_TASK_EXIT:
			err = blocking_notifier_chain_register(
					&task_exit_notifier, n);
			break;
		case PROFILE_MUNMAP:
			err = blocking_notifier_chain_register(
					&munmap_notifier, n);
			break;
	}
 
	return err;
}

 
int profile_event_unregister(enum profile_type type, struct notifier_block * n)
{
	int err = -EINVAL;
 
	switch (type) {
		case PROFILE_TASK_EXIT:
			err = blocking_notifier_chain_unregister(
					&task_exit_notifier, n);
			break;
		case PROFILE_MUNMAP:
			err = blocking_notifier_chain_unregister(
					&munmap_notifier, n);
			break;
	}

	return err;
}

int register_timer_hook(int (*hook)(struct pt_regs *))
{
	if (timer_hook)
		return -EBUSY;
	timer_hook = hook;
	return 0;
}

void unregister_timer_hook(int (*hook)(struct pt_regs *))
{
	WARN_ON(hook != timer_hook);
	timer_hook = NULL;
	/* make sure all CPUs see the NULL hook */
	synchronize_sched();  /* Allow ongoing interrupts to complete. */
}

EXPORT_SYMBOL_GPL(register_timer_hook);
EXPORT_SYMBOL_GPL(unregister_timer_hook);
EXPORT_SYMBOL_GPL(task_handoff_register);
EXPORT_SYMBOL_GPL(task_handoff_unregister);

#endif /* CONFIG_PROFILING */

EXPORT_SYMBOL_GPL(profile_event_register);
EXPORT_SYMBOL_GPL(profile_event_unregister);

#ifdef CONFIG_SMP
/*
 * Each cpu has a pair of open-addressed hashtables for pending
 * profile hits. read_profile() IPI's all cpus to request them
 * to flip buffers and flushes their contents to prof_buffer itself.
 * Flip requests are serialized by the profile_flip_mutex. The sole
 * use of having a second hashtable is for avoiding cacheline
 * contention that would otherwise happen during flushes of pending
 * profile hits required for the accuracy of reported profile hits
 * and so resurrect the interrupt livelock issue.
 *
 * The open-addressed hashtables are indexed by profile buffer slot
 * and hold the number of pending hits to that profile buffer slot on
 * a cpu in an entry. When the hashtable overflows, all pending hits
 * are accounted to their corresponding profile buffer slots with
 * atomic_add() and the hashtable emptied. As numerous pending hits
 * may be accounted to a profile buffer slot in a hashtable entry,
 * this amortizes a number of atomic profile buffer increments likely
 * to be far larger than the number of entries in the hashtable,
 * particularly given that the number of distinct profile buffer
 * positions to which hits are accounted during short intervals (e.g.
 * several seconds) is usually very small. Exclusion from buffer
 * flipping is provided by interrupt disablement (note that for
 * SCHED_PROFILING profile_hit() may be called from process context).
 * The hash function is meant to be lightweight as opposed to strong,
 * and was vaguely inspired by ppc64 firmware-supported inverted
 * pagetable hash functions, but uses a full hashtable full of finite
 * collision chains, not just pairs of them.
 *
 * -- wli
 */
static void __profile_flip_buffers(void *unused)
{
	int cpu = smp_processor_id();

	per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
}

static void profile_flip_buffers(void)
{
	int i, j, cpu;

	mutex_lock(&profile_flip_mutex);
	j = per_cpu(cpu_profile_flip, get_cpu());
	put_cpu();
	on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
	for_each_online_cpu(cpu) {
		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
		for (i = 0; i < NR_PROFILE_HIT; ++i) {
			if (!hits[i].hits) {
				if (hits[i].pc)
					hits[i].pc = 0;
				continue;
			}
			atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
			hits[i].hits = hits[i].pc = 0;
		}
	}
	mutex_unlock(&profile_flip_mutex);
}

static void profile_discard_flip_buffers(void)
{
	int i, cpu;

	mutex_lock(&profile_flip_mutex);
	i = per_cpu(cpu_profile_flip, get_cpu());
	put_cpu();
	on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
	for_each_online_cpu(cpu) {
		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
		memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
	}
	mutex_unlock(&profile_flip_mutex);
}

void profile_hit(int type, void *__pc)
{
	unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
	int i, j, cpu;
	struct profile_hit *hits;

	if (prof_on != type || !prof_buffer)
		return;
	pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
	i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
	secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
	cpu = get_cpu();
	hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
	if (!hits) {
		put_cpu();
		return;
	}
	local_irq_save(flags);
	do {
		for (j = 0; j < PROFILE_GRPSZ; ++j) {
			if (hits[i + j].pc == pc) {
				hits[i + j].hits++;
				goto out;
			} else if (!hits[i + j].hits) {
				hits[i + j].pc = pc;
				hits[i + j].hits = 1;
				goto out;
			}
		}
		i = (i + secondary) & (NR_PROFILE_HIT - 1);
	} while (i != primary);
	atomic_inc(&prof_buffer[pc]);
	for (i = 0; i < NR_PROFILE_HIT; ++i) {
		atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
		hits[i].pc = hits[i].hits = 0;
	}
out:
	local_irq_restore(flags);
	put_cpu();
}

#ifdef CONFIG_HOTPLUG_CPU
static int __devinit profile_cpu_callback(struct notifier_block *info,
					unsigned long action, void *__cpu)
{
	int node, cpu = (unsigned long)__cpu;
	struct page *page;

	switch (action) {
	case CPU_UP_PREPARE:
		node = cpu_to_node(cpu);
		per_cpu(cpu_profile_flip, cpu) = 0;
		if (!per_cpu(cpu_profile_hits, cpu)[1]) {
			page = alloc_pages_node(node,
					GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
					0);
			if (!page)
				return NOTIFY_BAD;
			per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
		}
		if (!per_cpu(cpu_profile_hits, cpu)[0]) {
			page = alloc_pages_node(node,
					GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
					0);
			if (!page)
				goto out_free;
			per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
		}
		break;
	out_free:
		page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
		per_cpu(cpu_profile_hits, cpu)[1] = NULL;
		__free_page(page);
		return NOTIFY_BAD;
	case CPU_ONLINE:
		cpu_set(cpu, prof_cpu_mask);
		break;
	case CPU_UP_CANCELED:
	case CPU_DEAD:
		cpu_clear(cpu, prof_cpu_mask);
		if (per_cpu(cpu_profile_hits, cpu)[0]) {
			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
			per_cpu(cpu_profile_hits, cpu)[0] = NULL;
			__free_page(page);
		}
		if (per_cpu(cpu_profile_hits, cpu)[1]) {
			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
			per_cpu(cpu_profile_hits, cpu)[1] = NULL;
			__free_page(page);
		}
		break;
	}
	return NOTIFY_OK;
}
#endif /* CONFIG_HOTPLUG_CPU */
#else /* !CONFIG_SMP */
#define profile_flip_buffers()		do { } while (0)
#define profile_discard_flip_buffers()	do { } while (0)

void profile_hit(int type, void *__pc)
{
	unsigned long pc;

	if (prof_on != type || !prof_buffer)
		return;
	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
	atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);
}
#endif /* !CONFIG_SMP */

void profile_tick(int type, struct pt_regs *regs)
{
	if (type == CPU_PROFILING && timer_hook)
		timer_hook(regs);
	if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
		profile_hit(type, (void *)profile_pc(regs));
}

#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>

static int prof_cpu_mask_read_proc (char *page, char **start, off_t off,
			int count, int *eof, void *data)
{
	int len = cpumask_scnprintf(page, count, *(cpumask_t *)data);
	if (count - len < 2)
		return -EINVAL;
	len += sprintf(page + len, "\n");
	return len;
}

static int prof_cpu_mask_write_proc (struct file *file, const char __user *buffer,
					unsigned long count, void *data)
{
	cpumask_t *mask = (cpumask_t *)data;
	unsigned long full_count = count, err;
	cpumask_t new_value;

	err = cpumask_parse(buffer, count, new_value);
	if (err)
		return err;

	*mask = new_value;
	return full_count;
}

void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
{
	struct proc_dir_entry *entry;

	/* create /proc/irq/prof_cpu_mask */
	if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir)))
		return;
	entry->nlink = 1;
	entry->data = (void *)&prof_cpu_mask;
	entry->read_proc = prof_cpu_mask_read_proc;
	entry->write_proc = prof_cpu_mask_write_proc;
}

/*
 * This function accesses profiling information. The returned data is
 * binary: the sampling step and the actual contents of the profile
 * buffer. Use of the program readprofile is recommended in order to
 * get meaningful info out of these data.
 */
static ssize_t
read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
	unsigned long p = *ppos;
	ssize_t read;
	char * pnt;
	unsigned int sample_step = 1 << prof_shift;

	profile_flip_buffers();
	if (p >= (prof_len+1)*sizeof(unsigned int))
		return 0;
	if (count > (prof_len+1)*sizeof(unsigned int) - p)
		count = (prof_len+1)*sizeof(unsigned int) - p;
	read = 0;

	while (p < sizeof(unsigned int) && count > 0) {
		put_user(*((char *)(&sample_step)+p),buf);
		buf++; p++; count--; read++;
	}
	pnt = (char *)prof_buffer + p - sizeof(atomic_t);
	if (copy_to_user(buf,(void *)pnt,count))
		return -EFAULT;
	read += count;
	*ppos += read;
	return read;
}

/*
 * Writing to /proc/profile resets the counters
 *
 * Writing a 'profiling multiplier' value into it also re-sets the profiling
 * interrupt frequency, on architectures that support this.
 */
static ssize_t write_profile(struct file *file, const char __user *buf,
			     size_t count, loff_t *ppos)
{
#ifdef CONFIG_SMP
	extern int setup_profiling_timer (unsigned int multiplier);

	if (count == sizeof(int)) {
		unsigned int multiplier;

		if (copy_from_user(&multiplier, buf, sizeof(int)))
			return -EFAULT;

		if (setup_profiling_timer(multiplier))
			return -EINVAL;
	}
#endif
	profile_discard_flip_buffers();
	memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
	return count;
}

static struct file_operations proc_profile_operations = {
	.read		= read_profile,
	.write		= write_profile,
};

#ifdef CONFIG_SMP
static void __init profile_nop(void *unused)
{
}

static int __init create_hash_tables(void)
{
	int cpu;

	for_each_online_cpu(cpu) {
		int node = cpu_to_node(cpu);
		struct page *page;

		page = alloc_pages_node(node,
				GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
				0);
		if (!page)
			goto out_cleanup;
		per_cpu(cpu_profile_hits, cpu)[1]
				= (struct profile_hit *)page_address(page);
		page = alloc_pages_node(node,
				GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
				0);
		if (!page)
			goto out_cleanup;
		per_cpu(cpu_profile_hits, cpu)[0]
				= (struct profile_hit *)page_address(page);
	}
	return 0;
out_cleanup:
	prof_on = 0;
	smp_mb();
	on_each_cpu(profile_nop, NULL, 0, 1);
	for_each_online_cpu(cpu) {
		struct page *page;

		if (per_cpu(cpu_profile_hits, cpu)[0]) {
			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
			per_cpu(cpu_profile_hits, cpu)[0] = NULL;
			__free_page(page);
		}
		if (per_cpu(cpu_profile_hits, cpu)[1]) {
			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
			per_cpu(cpu_profile_hits, cpu)[1] = NULL;
			__free_page(page);
		}
	}
	return -1;
}
#else
#define create_hash_tables()			({ 0; })
#endif

static int __init create_proc_profile(void)
{
	struct proc_dir_entry *entry;

	if (!prof_on)
		return 0;
	if (create_hash_tables())
		return -1;
	if (!(entry = create_proc_entry("profile", S_IWUSR | S_IRUGO, NULL)))
		return 0;
	entry->proc_fops = &proc_profile_operations;
	entry->size = (1+prof_len) * sizeof(atomic_t);
	hotcpu_notifier(profile_cpu_callback, 0);
	return 0;
}
module_init(create_proc_profile);
#endif /* CONFIG_PROC_FS */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/kernel/profile.c
	3	* Simple profiling. Manages a direct-mapped profile hit count buffer,
	4	* with configurable resolution, support for restricting the cpus on
	5	* which profiling is done, and switching between cpu time and
	6	* schedule() calls via kernel command line parameters passed at boot.
	7	*
	8	* Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
	9	* Red Hat, July 2004
	10	* Consolidation of architecture support code for profiling,
	11	* William Irwin, Oracle, July 2004
	12	* Amortized hit count accounting via per-cpu open-addressed hashtables
	13	* to resolve timer interrupt livelocks, William Irwin, Oracle, 2004
	14	*/
	15
1da177e4 LT	16	#include <linux/module.h>
	17	#include <linux/profile.h>
	18	#include <linux/bootmem.h>
	19	#include <linux/notifier.h>
	20	#include <linux/mm.h>
	21	#include <linux/cpumask.h>
	22	#include <linux/cpu.h>
	23	#include <linux/profile.h>
	24	#include <linux/highmem.h>
97d1f15b	25	#include <linux/mutex.h>
1da177e4 LT	26	#include <asm/sections.h>
	27	#include <asm/semaphore.h>
	28
	29	struct profile_hit {
	30	u32 pc, hits;
	31	};
	32	#define PROFILE_GRPSHIFT 3
	33	#define PROFILE_GRPSZ (1 << PROFILE_GRPSHIFT)
	34	#define NR_PROFILE_HIT (PAGE_SIZE/sizeof(struct profile_hit))
	35	#define NR_PROFILE_GRP (NR_PROFILE_HIT/PROFILE_GRPSZ)
	36
	37	/* Oprofile timer tick hook */
6c036527	38	int (timer_hook)(struct pt_regs ) __read_mostly;
1da177e4 LT	39
	40	static atomic_t *prof_buffer;
	41	static unsigned long prof_len, prof_shift;
6c036527	42	static int prof_on __read_mostly;
1da177e4 LT	43	static cpumask_t prof_cpu_mask = CPU_MASK_ALL;
	44	#ifdef CONFIG_SMP
	45	static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
	46	static DEFINE_PER_CPU(int, cpu_profile_flip);
97d1f15b	47	static DEFINE_MUTEX(profile_flip_mutex);
1da177e4 LT	48	#endif /* CONFIG_SMP */
	49
	50	static int __init profile_setup(char * str)
	51	{
dfaa9c94	52	static char __initdata schedstr[] = "schedule";
1da177e4 LT	53	int par;
1da177e4 LT	54
dfaa9c94	55	if (!strncmp(str, schedstr, strlen(schedstr))) {
1da177e4	56	prof_on = SCHED_PROFILING;
dfaa9c94 NYC	57	if (str[strlen(schedstr)] == ',')
	58	str += strlen(schedstr) + 1;
	59	if (get_option(&str, &par))
	60	prof_shift = par;
	61	printk(KERN_INFO
	62	"kernel schedule profiling enabled (shift: %ld)\n",
	63	prof_shift);
	64	} else if (get_option(&str, &par)) {
1da177e4 LT	65	prof_shift = par;
	66	prof_on = CPU_PROFILING;
	67	printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
	68	prof_shift);
	69	}
	70	return 1;
	71	}
	72	__setup("profile=", profile_setup);
	73
	74
	75	void __init profile_init(void)
	76	{
	77	if (!prof_on)
	78	return;
	79
	80	/* only text is profiled */
	81	prof_len = (_etext - _stext) >> prof_shift;
	82	prof_buffer = alloc_bootmem(prof_len*sizeof(atomic_t));
	83	}
	84
	85	/* Profile event notifications */
	86
	87	#ifdef CONFIG_PROFILING
	88
e041c683 AS	89	static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
	90	static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
	91	static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
1da177e4 LT	92
	93	void profile_task_exit(struct task_struct * task)
	94	{
e041c683	95	blocking_notifier_call_chain(&task_exit_notifier, 0, task);
1da177e4 LT	96	}
	97
	98	int profile_handoff_task(struct task_struct * task)
	99	{
	100	int ret;
e041c683	101	ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
1da177e4 LT	102	return (ret == NOTIFY_OK) ? 1 : 0;
	103	}
	104
	105	void profile_munmap(unsigned long addr)
	106	{
e041c683	107	blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
1da177e4 LT	108	}
	109
	110	int task_handoff_register(struct notifier_block * n)
	111	{
e041c683	112	return atomic_notifier_chain_register(&task_free_notifier, n);
1da177e4 LT	113	}
	114
	115	int task_handoff_unregister(struct notifier_block * n)
	116	{
e041c683	117	return atomic_notifier_chain_unregister(&task_free_notifier, n);
1da177e4 LT	118	}
	119
	120	int profile_event_register(enum profile_type type, struct notifier_block * n)
	121	{
	122	int err = -EINVAL;
	123
1da177e4 LT	124	switch (type) {
1da177e4 LT	125	case PROFILE_TASK_EXIT:
e041c683 AS	126	err = blocking_notifier_chain_register(
e041c683 AS	127	&task_exit_notifier, n);
1da177e4 LT	128	break;
1da177e4 LT	129	case PROFILE_MUNMAP:
e041c683 AS	130	err = blocking_notifier_chain_register(
e041c683 AS	131	&munmap_notifier, n);
1da177e4 LT	132	break;
	133	}
	134
1da177e4 LT	135	return err;
	136	}
	137
	138
	139	int profile_event_unregister(enum profile_type type, struct notifier_block * n)
	140	{
	141	int err = -EINVAL;
	142
1da177e4 LT	143	switch (type) {
1da177e4 LT	144	case PROFILE_TASK_EXIT:
e041c683 AS	145	err = blocking_notifier_chain_unregister(
e041c683 AS	146	&task_exit_notifier, n);
1da177e4 LT	147	break;
1da177e4 LT	148	case PROFILE_MUNMAP:
e041c683 AS	149	err = blocking_notifier_chain_unregister(
e041c683 AS	150	&munmap_notifier, n);
1da177e4 LT	151	break;
	152	}
	153
1da177e4 LT	154	return err;
	155	}
	156
	157	int register_timer_hook(int (hook)(struct pt_regs ))
	158	{
	159	if (timer_hook)
	160	return -EBUSY;
	161	timer_hook = hook;
	162	return 0;
	163	}
	164
	165	void unregister_timer_hook(int (hook)(struct pt_regs ))
	166	{
	167	WARN_ON(hook != timer_hook);
	168	timer_hook = NULL;
	169	/* make sure all CPUs see the NULL hook */
fbd568a3	170	synchronize_sched(); /* Allow ongoing interrupts to complete. */
1da177e4 LT	171	}
	172
	173	EXPORT_SYMBOL_GPL(register_timer_hook);
	174	EXPORT_SYMBOL_GPL(unregister_timer_hook);
	175	EXPORT_SYMBOL_GPL(task_handoff_register);
	176	EXPORT_SYMBOL_GPL(task_handoff_unregister);
	177
	178	#endif /* CONFIG_PROFILING */
	179
	180	EXPORT_SYMBOL_GPL(profile_event_register);
	181	EXPORT_SYMBOL_GPL(profile_event_unregister);
	182
	183	#ifdef CONFIG_SMP
	184	/*
	185	* Each cpu has a pair of open-addressed hashtables for pending
	186	* profile hits. read_profile() IPI's all cpus to request them
	187	* to flip buffers and flushes their contents to prof_buffer itself.
	188	* Flip requests are serialized by the profile_flip_mutex. The sole
	189	* use of having a second hashtable is for avoiding cacheline
	190	* contention that would otherwise happen during flushes of pending
	191	* profile hits required for the accuracy of reported profile hits
	192	* and so resurrect the interrupt livelock issue.
	193	*
	194	* The open-addressed hashtables are indexed by profile buffer slot
	195	* and hold the number of pending hits to that profile buffer slot on
	196	* a cpu in an entry. When the hashtable overflows, all pending hits
	197	* are accounted to their corresponding profile buffer slots with
	198	* atomic_add() and the hashtable emptied. As numerous pending hits
	199	* may be accounted to a profile buffer slot in a hashtable entry,
	200	* this amortizes a number of atomic profile buffer increments likely
	201	* to be far larger than the number of entries in the hashtable,
	202	* particularly given that the number of distinct profile buffer
	203	* positions to which hits are accounted during short intervals (e.g.
	204	* several seconds) is usually very small. Exclusion from buffer
	205	* flipping is provided by interrupt disablement (note that for
	206	* SCHED_PROFILING profile_hit() may be called from process context).
	207	* The hash function is meant to be lightweight as opposed to strong,
	208	* and was vaguely inspired by ppc64 firmware-supported inverted
	209	* pagetable hash functions, but uses a full hashtable full of finite
	210	* collision chains, not just pairs of them.
	211	*
	212	* -- wli
	213	*/
	214	static void __profile_flip_buffers(void *unused)
	215	{
	216	int cpu = smp_processor_id();
	217
	218	per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
	219	}
	220
	221	static void profile_flip_buffers(void)
	222	{
	223	int i, j, cpu;
	224
97d1f15b	225	mutex_lock(&profile_flip_mutex);
1da177e4 LT	226	j = per_cpu(cpu_profile_flip, get_cpu());
	227	put_cpu();
	228	on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
	229	for_each_online_cpu(cpu) {
	230	struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
	231	for (i = 0; i < NR_PROFILE_HIT; ++i) {
	232	if (!hits[i].hits) {
	233	if (hits[i].pc)
	234	hits[i].pc = 0;
	235	continue;
	236	}
	237	atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
	238	hits[i].hits = hits[i].pc = 0;
	239	}
	240	}
97d1f15b	241	mutex_unlock(&profile_flip_mutex);
1da177e4 LT	242	}
	243
	244	static void profile_discard_flip_buffers(void)
	245	{
	246	int i, cpu;
	247
97d1f15b	248	mutex_lock(&profile_flip_mutex);
1da177e4 LT	249	i = per_cpu(cpu_profile_flip, get_cpu());
	250	put_cpu();
	251	on_each_cpu(__profile_flip_buffers, NULL, 0, 1);
	252	for_each_online_cpu(cpu) {
	253	struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
	254	memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
	255	}
97d1f15b	256	mutex_unlock(&profile_flip_mutex);
1da177e4 LT	257	}
	258
	259	void profile_hit(int type, void *__pc)
	260	{
	261	unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
	262	int i, j, cpu;
	263	struct profile_hit *hits;
	264
	265	if (prof_on != type \|\| !prof_buffer)
	266	return;
	267	pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
	268	i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
	269	secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
	270	cpu = get_cpu();
	271	hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
	272	if (!hits) {
	273	put_cpu();
	274	return;
	275	}
	276	local_irq_save(flags);
	277	do {
	278	for (j = 0; j < PROFILE_GRPSZ; ++j) {
	279	if (hits[i + j].pc == pc) {
	280	hits[i + j].hits++;
	281	goto out;
	282	} else if (!hits[i + j].hits) {
	283	hits[i + j].pc = pc;
	284	hits[i + j].hits = 1;
	285	goto out;
	286	}
	287	}
	288	i = (i + secondary) & (NR_PROFILE_HIT - 1);
	289	} while (i != primary);
	290	atomic_inc(&prof_buffer[pc]);
	291	for (i = 0; i < NR_PROFILE_HIT; ++i) {
	292	atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
	293	hits[i].pc = hits[i].hits = 0;
	294	}
	295	out:
	296	local_irq_restore(flags);
	297	put_cpu();
	298	}
	299
	300	#ifdef CONFIG_HOTPLUG_CPU
9c7b216d	301	static int __devinit profile_cpu_callback(struct notifier_block *info,
1da177e4 LT	302	unsigned long action, void *__cpu)
	303	{
	304	int node, cpu = (unsigned long)__cpu;
	305	struct page *page;
	306
	307	switch (action) {
	308	case CPU_UP_PREPARE:
	309	node = cpu_to_node(cpu);
	310	per_cpu(cpu_profile_flip, cpu) = 0;
	311	if (!per_cpu(cpu_profile_hits, cpu)[1]) {
fbd98167 CL	312	page = alloc_pages_node(node,
	313	GFP_KERNEL \| __GFP_ZERO \| GFP_THISNODE,
	314	0);
1da177e4 LT	315	if (!page)
	316	return NOTIFY_BAD;
	317	per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
	318	}
	319	if (!per_cpu(cpu_profile_hits, cpu)[0]) {
fbd98167 CL	320	page = alloc_pages_node(node,
	321	GFP_KERNEL \| __GFP_ZERO \| GFP_THISNODE,
	322	0);
1da177e4 LT	323	if (!page)
	324	goto out_free;
	325	per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
	326	}
	327	break;
	328	out_free:
	329	page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
	330	per_cpu(cpu_profile_hits, cpu)[1] = NULL;
	331	__free_page(page);
	332	return NOTIFY_BAD;
	333	case CPU_ONLINE:
	334	cpu_set(cpu, prof_cpu_mask);
	335	break;
	336	case CPU_UP_CANCELED:
	337	case CPU_DEAD:
	338	cpu_clear(cpu, prof_cpu_mask);
	339	if (per_cpu(cpu_profile_hits, cpu)[0]) {
	340	page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
	341	per_cpu(cpu_profile_hits, cpu)[0] = NULL;
	342	__free_page(page);
	343	}
	344	if (per_cpu(cpu_profile_hits, cpu)[1]) {
	345	page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
	346	per_cpu(cpu_profile_hits, cpu)[1] = NULL;
	347	__free_page(page);
	348	}
	349	break;
	350	}
	351	return NOTIFY_OK;
	352	}
	353	#endif /* CONFIG_HOTPLUG_CPU */
	354	#else /* !CONFIG_SMP */
	355	#define profile_flip_buffers() do { } while (0)
	356	#define profile_discard_flip_buffers() do { } while (0)
	357
	358	void profile_hit(int type, void *__pc)
	359	{
	360	unsigned long pc;
	361
	362	if (prof_on != type \|\| !prof_buffer)
	363	return;
	364	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
	365	atomic_inc(&prof_buffer[min(pc, prof_len - 1)]);
	366	}
	367	#endif /* !CONFIG_SMP */
	368
	369	void profile_tick(int type, struct pt_regs *regs)
	370	{
	371	if (type == CPU_PROFILING && timer_hook)
	372	timer_hook(regs);
	373	if (!user_mode(regs) && cpu_isset(smp_processor_id(), prof_cpu_mask))
	374	profile_hit(type, (void *)profile_pc(regs));
	375	}
	376
	377	#ifdef CONFIG_PROC_FS
	378	#include <linux/proc_fs.h>
	379	#include <asm/uaccess.h>
	380	#include <asm/ptrace.h>
	381
	382	static int prof_cpu_mask_read_proc (char page, char *start, off_t off,
	383	int count, int eof, void data)
	384	{
	385	int len = cpumask_scnprintf(page, count, (cpumask_t )data);
	386	if (count - len < 2)
387	return -EINVAL;
388	len += sprintf(page + len, "\n");
389	return len;
390	}
391
392	static int prof_cpu_mask_write_proc (struct file file, const char __user buffer,
393	unsigned long count, void *data)
394	{
395	cpumask_t mask = (cpumask_t )data;
396	unsigned long full_count = count, err;
397	cpumask_t new_value;
398
399	err = cpumask_parse(buffer, count, new_value);
400	if (err)
401	return err;
402
403	*mask = new_value;
404	return full_count;
405	}
406
407	void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
408	{
409	struct proc_dir_entry *entry;
410
411	/* create /proc/irq/prof_cpu_mask */
412	if (!(entry = create_proc_entry("prof_cpu_mask", 0600, root_irq_dir)))
413	return;
414	entry->nlink = 1;
415	entry->data = (void *)&prof_cpu_mask;
416	entry->read_proc = prof_cpu_mask_read_proc;
417	entry->write_proc = prof_cpu_mask_write_proc;
418	}
419
420	/*
421	* This function accesses profiling information. The returned data is
422	* binary: the sampling step and the actual contents of the profile
423	* buffer. Use of the program readprofile is recommended in order to
424	* get meaningful info out of these data.
425	*/
426	static ssize_t
427	read_profile(struct file file, char __user buf, size_t count, loff_t *ppos)
428	{
429	unsigned long p = *ppos;
430	ssize_t read;
431	char * pnt;
432	unsigned int sample_step = 1 << prof_shift;
433
434	profile_flip_buffers();
435	if (p >= (prof_len+1)*sizeof(unsigned int))
436	return 0;
437	if (count > (prof_len+1)*sizeof(unsigned int) - p)
438	count = (prof_len+1)*sizeof(unsigned int) - p;
439	read = 0;
440
441	while (p < sizeof(unsigned int) && count > 0) {
442	put_user(((char )(&sample_step)+p),buf);
443	buf++; p++; count--; read++;
444	}
445	pnt = (char *)prof_buffer + p - sizeof(atomic_t);
446	if (copy_to_user(buf,(void *)pnt,count))
447	return -EFAULT;
448	read += count;
449	*ppos += read;
450	return read;
451	}
452
453	/*
454	* Writing to /proc/profile resets the counters
455	*
456	* Writing a 'profiling multiplier' value into it also re-sets the profiling
457	* interrupt frequency, on architectures that support this.
458	*/
459	static ssize_t write_profile(struct file file, const char __user buf,
460	size_t count, loff_t *ppos)
461	{
462	#ifdef CONFIG_SMP
463	extern int setup_profiling_timer (unsigned int multiplier);
464
465	if (count == sizeof(int)) {
466	unsigned int multiplier;
467
468	if (copy_from_user(&multiplier, buf, sizeof(int)))
469	return -EFAULT;
470
471	if (setup_profiling_timer(multiplier))
472	return -EINVAL;
473	}
474	#endif
475	profile_discard_flip_buffers();
476	memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
477	return count;
478	}
479
480	static struct file_operations proc_profile_operations = {
481	.read = read_profile,
482	.write = write_profile,
483	};
484
485	#ifdef CONFIG_SMP
486	static void __init profile_nop(void *unused)
487	{
488	}
489
490	static int __init create_hash_tables(void)
491	{
492	int cpu;
493
494	for_each_online_cpu(cpu) {
495	int node = cpu_to_node(cpu);
496	struct page *page;
497
fbd98167 CL	498	page = alloc_pages_node(node,
	499	GFP_KERNEL \| __GFP_ZERO \| GFP_THISNODE,
	500	0);
1da177e4 LT	501	if (!page)
	502	goto out_cleanup;
	503	per_cpu(cpu_profile_hits, cpu)[1]
	504	= (struct profile_hit *)page_address(page);
fbd98167 CL	505	page = alloc_pages_node(node,
	506	GFP_KERNEL \| __GFP_ZERO \| GFP_THISNODE,
	507	0);
1da177e4 LT	508	if (!page)
	509	goto out_cleanup;
	510	per_cpu(cpu_profile_hits, cpu)[0]
	511	= (struct profile_hit *)page_address(page);
	512	}
	513	return 0;
	514	out_cleanup:
	515	prof_on = 0;
d59dd462	516	smp_mb();
1da177e4 LT	517	on_each_cpu(profile_nop, NULL, 0, 1);
	518	for_each_online_cpu(cpu) {
	519	struct page *page;
	520
	521	if (per_cpu(cpu_profile_hits, cpu)[0]) {
	522	page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
	523	per_cpu(cpu_profile_hits, cpu)[0] = NULL;
	524	__free_page(page);
	525	}
	526	if (per_cpu(cpu_profile_hits, cpu)[1]) {
	527	page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
	528	per_cpu(cpu_profile_hits, cpu)[1] = NULL;
	529	__free_page(page);
	530	}
	531	}
	532	return -1;
	533	}
	534	#else
	535	#define create_hash_tables() ({ 0; })
	536	#endif
	537
	538	static int __init create_proc_profile(void)
	539	{
	540	struct proc_dir_entry *entry;
	541
	542	if (!prof_on)
	543	return 0;
	544	if (create_hash_tables())
	545	return -1;
	546	if (!(entry = create_proc_entry("profile", S_IWUSR \| S_IRUGO, NULL)))
	547	return 0;
	548	entry->proc_fops = &proc_profile_operations;
	549	entry->size = (1+prof_len) * sizeof(atomic_t);
	550	hotcpu_notifier(profile_cpu_callback, 0);
	551	return 0;
	552	}
	553	module_init(create_proc_profile);
	554	#endif /* CONFIG_PROC_FS */