/* *  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/config.h>#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 <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 *); static atomic_t *prof_buffer;static unsigned long prof_len, prof_shift;static int prof_on;static cpumask_t prof_cpu_mask = CPU_MASK_ALL;#ifdef CONFIG_SMPstatic DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);static DEFINE_PER_CPU(int, cpu_profile_flip);static DECLARE_MUTEX(profile_flip_mutex);#endif /* CONFIG_SMP */ static int __init profile_setup(char * str){	int par; 	if (!strncmp(str, "schedule", 8)) {		prof_on = SCHED_PROFILING;		printk(KERN_INFO "kernel schedule profiling enabled\n");		if (str[7] == ',')			str += 8;	}	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 DECLARE_RWSEM(profile_rwsem);static DEFINE_RWLOCK(handoff_lock);static struct notifier_block * task_exit_notifier;static struct notifier_block * task_free_notifier;static struct notifier_block * munmap_notifier; void profile_task_exit(struct task_struct * task){	down_read(&profile_rwsem);	notifier_call_chain(&task_exit_notifier, 0, task);	up_read(&profile_rwsem);} int profile_handoff_task(struct task_struct * task){	int ret;	read_lock(&handoff_lock);	ret = notifier_call_chain(&task_free_notifier, 0, task);	read_unlock(&handoff_lock);	return (ret == NOTIFY_OK) ? 1 : 0;} void profile_munmap(unsigned long addr){	down_read(&profile_rwsem);	notifier_call_chain(&munmap_notifier, 0, (void *)addr);	up_read(&profile_rwsem);} int task_handoff_register(struct notifier_block * n){	int err = -EINVAL; 	write_lock(&handoff_lock);	err = notifier_chain_register(&task_free_notifier, n);	write_unlock(&handoff_lock);	return err;} int task_handoff_unregister(struct notifier_block * n){	int err = -EINVAL; 	write_lock(&handoff_lock);	err = notifier_chain_unregister(&task_free_notifier, n);	write_unlock(&handoff_lock);	return err;} int profile_event_register(enum profile_type type, struct notifier_block * n){	int err = -EINVAL; 	down_write(&profile_rwsem); 	switch (type) {		case PROFILE_TASK_EXIT:			err = notifier_chain_register(&task_exit_notifier, n);			break;		case PROFILE_MUNMAP:			err = notifier_chain_register(&munmap_notifier, n);			break;	} 	up_write(&profile_rwsem); 	return err;}  int profile_event_unregister(enum profile_type type, struct notifier_block * n){	int err = -EINVAL; 	down_write(&profile_rwsem); 	switch (type) {		case PROFILE_TASK_EXIT:			err = notifier_chain_unregister(&task_exit_notifier, n);			break;		case PROFILE_MUNMAP:			err = notifier_chain_unregister(&munmap_notifier, n);			break;	} 	up_write(&profile_rwsem);	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_kernel();} 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; 	down(&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;		}	}	up(&profile_flip_mutex);} static void profile_discard_flip_buffers(void){	int i, cpu; 	down(&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));	}	up(&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_CPUstatic 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, 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, 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_tread_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_SMPstatic void __init profile_nop(void *unused){

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