/* *  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/highmem.h>#include <linux/mutex.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <asm/sections.h>#include <asm/irq_regs.h>#include <asm/ptrace.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 */static int (*timer_hook)(struct pt_regs *) __read_mostly; static atomic_t *prof_buffer;static unsigned long prof_len, prof_shift; int prof_on __read_mostly;EXPORT_SYMBOL_GPL(prof_on); static cpumask_var_t prof_cpu_mask;#ifdef CONFIG_SMPstatic 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 */ int profile_setup(char *str){	static char schedstr[] = "schedule";	static char sleepstr[] = "sleep";	static char kvmstr[] = "kvm";	int par; 	if (!strncmp(str, sleepstr, strlen(sleepstr))) {#ifdef CONFIG_SCHEDSTATS		prof_on = SLEEP_PROFILING;		if (str[strlen(sleepstr)] == ',')			str += strlen(sleepstr) + 1;		if (get_option(&str, &par))			prof_shift = par;		printk(KERN_INFO			"kernel sleep profiling enabled (shift: %ld)\n",			prof_shift);#else		printk(KERN_WARNING			"kernel sleep profiling requires CONFIG_SCHEDSTATS\n");#endif /* CONFIG_SCHEDSTATS */	} else 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 (!strncmp(str, kvmstr, strlen(kvmstr))) {		prof_on = KVM_PROFILING;		if (str[strlen(kvmstr)] == ',')			str += strlen(kvmstr) + 1;		if (get_option(&str, &par))			prof_shift = par;		printk(KERN_INFO			"kernel KVM 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);  int __ref profile_init(void){	int buffer_bytes;	if (!prof_on)		return 0; 	/* only text is profiled */	prof_len = (_etext - _stext) >> prof_shift;	buffer_bytes = prof_len*sizeof(atomic_t); 	if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))		return -ENOMEM; 	cpumask_copy(prof_cpu_mask, cpu_possible_mask); 	prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);	if (prof_buffer)		return 0; 	prof_buffer = alloc_pages_exact(buffer_bytes,					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);	if (prof_buffer)		return 0; 	prof_buffer = vmalloc(buffer_bytes);	if (prof_buffer) {		memset(prof_buffer, 0, buffer_bytes);		return 0;	} 	free_cpumask_var(prof_cpu_mask);	return -ENOMEM;} /* Profile event notifications */ 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);}EXPORT_SYMBOL_GPL(task_handoff_register); int task_handoff_unregister(struct notifier_block *n){	return atomic_notifier_chain_unregister(&task_free_notifier, n);}EXPORT_SYMBOL_GPL(task_handoff_unregister); 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;}EXPORT_SYMBOL_GPL(profile_event_register); 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;}EXPORT_SYMBOL_GPL(profile_event_unregister); int register_timer_hook(int (*hook)(struct pt_regs *)){	if (timer_hook)		return -EBUSY;	timer_hook = hook;	return 0;}EXPORT_SYMBOL_GPL(register_timer_hook); 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(unregister_timer_hook);  #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 or SLEEP_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, 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, 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_hits(int type, void *__pc, unsigned int nr_hits){	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;	}	/*	 * We buffer the global profiler buffer into a per-CPU	 * queue and thus reduce the number of global (and possibly	 * NUMA-alien) accesses. The write-queue is self-coalescing:	 */	local_irq_save(flags);	do {		for (j = 0; j < PROFILE_GRPSZ; ++j) {			if (hits[i + j].pc == pc) {				hits[i + j].hits += nr_hits;				goto out;			} else if (!hits[i + j].hits) {				hits[i + j].pc = pc;				hits[i + j].hits = nr_hits;				goto out;			}		}		i = (i + secondary) & (NR_PROFILE_HIT - 1);	} while (i != primary); 	/*	 * Add the current hit(s) and flush the write-queue out	 * to the global buffer:	 */	atomic_add(nr_hits, &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();} static int __cpuinit 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:	case CPU_UP_PREPARE_FROZEN:		node = cpu_to_mem(cpu);		per_cpu(cpu_profile_flip, cpu) = 0;		if (!per_cpu(cpu_profile_hits, cpu)[1]) {			page = alloc_pages_exact_node(node,					GFP_KERNEL | __GFP_ZERO,					0);			if (!page)				return notifier_from_errno(-ENOMEM);			per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);		}		if (!per_cpu(cpu_profile_hits, cpu)[0]) {			page = alloc_pages_exact_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 notifier_from_errno(-ENOMEM);	case CPU_ONLINE:	case CPU_ONLINE_FROZEN:		if (prof_cpu_mask != NULL)			cpumask_set_cpu(cpu, prof_cpu_mask);		break;	case CPU_UP_CANCELED:	case CPU_UP_CANCELED_FROZEN:	case CPU_DEAD:	case CPU_DEAD_FROZEN:		if (prof_cpu_mask != NULL)			cpumask_clear_cpu(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;}#else /* !CONFIG_SMP */#define profile_flip_buffers()		do { } while (0)#define profile_discard_flip_buffers()	do { } while (0)#define profile_cpu_callback		NULL void profile_hits(int type, void *__pc, unsigned int nr_hits){	unsigned long pc; 	if (prof_on != type || !prof_buffer)		return;	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;	atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);}#endif /* !CONFIG_SMP */EXPORT_SYMBOL_GPL(profile_hits); void profile_tick(int type){	struct pt_regs *regs = get_irq_regs(); 	if (type == CPU_PROFILING && timer_hook)		timer_hook(regs);	if (!user_mode(regs) && prof_cpu_mask != NULL &&	    cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))		profile_hit(type, (void *)profile_pc(regs));} #ifdef CONFIG_PROC_FS#include <linux/proc_fs.h>#include <linux/seq_file.h>#include <asm/uaccess.h> static int prof_cpu_mask_proc_show(struct seq_file *m, void *v){	seq_cpumask(m, prof_cpu_mask);	seq_putc(m, '\n');	return 0;} static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file){	return single_open(file, prof_cpu_mask_proc_show, NULL);} static ssize_t prof_cpu_mask_proc_write(struct file *file,	const char __user *buffer, size_t count, loff_t *pos){	cpumask_var_t new_value;	int err; 	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))		return -ENOMEM; 	err = cpumask_parse_user(buffer, count, new_value);	if (!err) {		cpumask_copy(prof_cpu_mask, new_value);		err = count;	}	free_cpumask_var(new_value);	return err;} static const struct file_operations prof_cpu_mask_proc_fops = {	.open		= prof_cpu_mask_proc_open,	.read		= seq_read,	.llseek		= seq_lseek,	.release	= single_release,	.write		= prof_cpu_mask_proc_write,}; void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir){	/* create /proc/irq/prof_cpu_mask */	proc_create("prof_cpu_mask", 0600, root_irq_dir, &prof_cpu_mask_proc_fops);} /* * 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

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