/** * @file cpu_buffer.c * * @remark Copyright 2002-2009 OProfile authors * @remark Read the file COPYING * * @author John Levon <levon@movementarian.org> * @author Barry Kasindorf <barry.kasindorf@amd.com> * @author Robert Richter <robert.richter@amd.com> * * Each CPU has a local buffer that stores PC value/event * pairs. We also log context switches when we notice them. * Eventually each CPU's buffer is processed into the global * event buffer by sync_buffer(). * * We use a local buffer for two reasons: an NMI or similar * interrupt cannot synchronise, and high sampling rates * would lead to catastrophic global synchronisation if * a global buffer was used. */ #include <linux/sched.h>#include <linux/oprofile.h>#include <linux/errno.h> #include "event_buffer.h"#include "cpu_buffer.h"#include "buffer_sync.h"#include "oprof.h" #define OP_BUFFER_FLAGS	0 static struct ring_buffer *op_ring_buffer;DEFINE_PER_CPU(struct oprofile_cpu_buffer, op_cpu_buffer); static void wq_sync_buffer(struct work_struct *work); #define DEFAULT_TIMER_EXPIRE (HZ / 10)static int work_enabled; unsigned long oprofile_get_cpu_buffer_size(void){	return oprofile_cpu_buffer_size;} void oprofile_cpu_buffer_inc_smpl_lost(void){	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer); 	cpu_buf->sample_lost_overflow++;} void free_cpu_buffers(void){	if (op_ring_buffer)		ring_buffer_free(op_ring_buffer);	op_ring_buffer = NULL;} #define RB_EVENT_HDR_SIZE 4 int alloc_cpu_buffers(void){	int i; 	unsigned long buffer_size = oprofile_cpu_buffer_size;	unsigned long byte_size = buffer_size * (sizeof(struct op_sample) +						 RB_EVENT_HDR_SIZE); 	op_ring_buffer = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);	if (!op_ring_buffer)		goto fail; 	for_each_possible_cpu(i) {		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); 		b->last_task = NULL;		b->last_is_kernel = -1;		b->tracing = 0;		b->buffer_size = buffer_size;		b->sample_received = 0;		b->sample_lost_overflow = 0;		b->backtrace_aborted = 0;		b->sample_invalid_eip = 0;		b->cpu = i;		INIT_DELAYED_WORK(&b->work, wq_sync_buffer);	}	return 0; fail:	free_cpu_buffers();	return -ENOMEM;} void start_cpu_work(void){	int i; 	work_enabled = 1; 	for_each_online_cpu(i) {		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); 		/*		 * Spread the work by 1 jiffy per cpu so they dont all		 * fire at once.		 */		schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);	}} void end_cpu_work(void){	work_enabled = 0;} void flush_cpu_work(void){	int i; 	for_each_online_cpu(i) {		struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); 		/* these works are per-cpu, no need for flush_sync */		flush_delayed_work(&b->work);	}} /* * This function prepares the cpu buffer to write a sample. * * Struct op_entry is used during operations on the ring buffer while * struct op_sample contains the data that is stored in the ring * buffer. Struct entry can be uninitialized. The function reserves a * data array that is specified by size. Use * op_cpu_buffer_write_commit() after preparing the sample. In case of * errors a null pointer is returned, otherwise the pointer to the * sample. * */struct op_sample*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size){	entry->event = ring_buffer_lock_reserve		(op_ring_buffer, sizeof(struct op_sample) +		 size * sizeof(entry->sample->data[0]));	if (!entry->event)		return NULL;	entry->sample = ring_buffer_event_data(entry->event);	entry->size = size;	entry->data = entry->sample->data; 	return entry->sample;} int op_cpu_buffer_write_commit(struct op_entry *entry){	return ring_buffer_unlock_commit(op_ring_buffer, entry->event);} struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu){	struct ring_buffer_event *e;	e = ring_buffer_consume(op_ring_buffer, cpu, NULL, NULL);	if (!e)		return NULL; 	entry->event = e;	entry->sample = ring_buffer_event_data(e);	entry->size = (ring_buffer_event_length(e) - sizeof(struct op_sample))		/ sizeof(entry->sample->data[0]);	entry->data = entry->sample->data;	return entry->sample;} unsigned long op_cpu_buffer_entries(int cpu){	return ring_buffer_entries_cpu(op_ring_buffer, cpu);} static intop_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,	    int is_kernel, struct task_struct *task){	struct op_entry entry;	struct op_sample *sample;	unsigned long flags;	int size; 	flags = 0; 	if (backtrace)		flags |= TRACE_BEGIN; 	/* notice a switch from user->kernel or vice versa */	is_kernel = !!is_kernel;	if (cpu_buf->last_is_kernel != is_kernel) {		cpu_buf->last_is_kernel = is_kernel;		flags |= KERNEL_CTX_SWITCH;		if (is_kernel)			flags |= IS_KERNEL;	} 	/* notice a task switch */	if (cpu_buf->last_task != task) {		cpu_buf->last_task = task;		flags |= USER_CTX_SWITCH;	} 	if (!flags)		/* nothing to do */		return 0; 	if (flags & USER_CTX_SWITCH)		size = 1;	else		size = 0; 	sample = op_cpu_buffer_write_reserve(&entry, size);	if (!sample)		return -ENOMEM; 	sample->eip = ESCAPE_CODE;	sample->event = flags; 	if (size)		op_cpu_buffer_add_data(&entry, (unsigned long)task); 	op_cpu_buffer_write_commit(&entry); 	return 0;} static inline intop_add_sample(struct oprofile_cpu_buffer *cpu_buf,	      unsigned long pc, unsigned long event){	struct op_entry entry;	struct op_sample *sample; 	sample = op_cpu_buffer_write_reserve(&entry, 0);	if (!sample)		return -ENOMEM; 	sample->eip = pc;	sample->event = event; 	return op_cpu_buffer_write_commit(&entry);} /* * This must be safe from any context. * * is_kernel is needed because on some architectures you cannot * tell if you are in kernel or user space simply by looking at * pc. We tag this in the buffer by generating kernel enter/exit * events whenever is_kernel changes */static intlog_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,	   unsigned long backtrace, int is_kernel, unsigned long event,	   struct task_struct *task){	struct task_struct *tsk = task ? task : current;	cpu_buf->sample_received++; 	if (pc == ESCAPE_CODE) {		cpu_buf->sample_invalid_eip++;		return 0;	} 	if (op_add_code(cpu_buf, backtrace, is_kernel, tsk))		goto fail; 	if (op_add_sample(cpu_buf, pc, event))		goto fail; 	return 1; fail:	cpu_buf->sample_lost_overflow++;	return 0;} static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf){	cpu_buf->tracing = 1;} static inline void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf){	cpu_buf->tracing = 0;} static inline void__oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,			  unsigned long event, int is_kernel,			  struct task_struct *task){	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);	unsigned long backtrace = oprofile_backtrace_depth; 	/*	 * if log_sample() fail we can't backtrace since we lost the	 * source of this event	 */	if (!log_sample(cpu_buf, pc, backtrace, is_kernel, event, task))		/* failed */		return; 	if (!backtrace)		return; 	oprofile_begin_trace(cpu_buf);	oprofile_ops.backtrace(regs, backtrace);	oprofile_end_trace(cpu_buf);} void oprofile_add_ext_hw_sample(unsigned long pc, struct pt_regs * const regs,				unsigned long event, int is_kernel,				struct task_struct *task){	__oprofile_add_ext_sample(pc, regs, event, is_kernel, task);} void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,			     unsigned long event, int is_kernel){	__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL);} void oprofile_add_sample(struct pt_regs * const regs, unsigned long event){	int is_kernel;	unsigned long pc; 	if (likely(regs)) {		is_kernel = !user_mode(regs);		pc = profile_pc(regs);	} else {		is_kernel = 0;    /* This value will not be used */		pc = ESCAPE_CODE; /* as this causes an early return. */	} 	__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL);} /* * Add samples with data to the ring buffer. * * Use oprofile_add_data(&entry, val) to add data and * oprofile_write_commit(&entry) to commit the sample. */voidoprofile_write_reserve(struct op_entry *entry, struct pt_regs * const regs,		       unsigned long pc, int code, int size){	struct op_sample *sample;	int is_kernel = !user_mode(regs);	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer); 	cpu_buf->sample_received++; 	/* no backtraces for samples with data */	if (op_add_code(cpu_buf, 0, is_kernel, current))		goto fail; 	sample = op_cpu_buffer_write_reserve(entry, size + 2);	if (!sample)		goto fail;	sample->eip = ESCAPE_CODE;	sample->event = 0;		/* no flags */ 	op_cpu_buffer_add_data(entry, code);	op_cpu_buffer_add_data(entry, pc); 	return; fail:	entry->event = NULL;	cpu_buf->sample_lost_overflow++;} int oprofile_add_data(struct op_entry *entry, unsigned long val){	if (!entry->event)		return 0;	return op_cpu_buffer_add_data(entry, val);} int oprofile_add_data64(struct op_entry *entry, u64 val){	if (!entry->event)		return 0;	if (op_cpu_buffer_get_size(entry) < 2)		/*		 * the function returns 0 to indicate a too small		 * buffer, even if there is some space left		 */		return 0;	if (!op_cpu_buffer_add_data(entry, (u32)val))		return 0;	return op_cpu_buffer_add_data(entry, (u32)(val >> 32));} int oprofile_write_commit(struct op_entry *entry){	if (!entry->event)		return -EINVAL;	return op_cpu_buffer_write_commit(entry);} void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event){	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);	log_sample(cpu_buf, pc, 0, is_kernel, event, NULL);} void oprofile_add_trace(unsigned long pc){	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer); 	if (!cpu_buf->tracing)		return; 	/*	 * broken frame can give an eip with the same value as an	 * escape code, abort the trace if we get it	 */	if (pc == ESCAPE_CODE)		goto fail; 	if (op_add_sample(cpu_buf, pc, 0))		goto fail; 	return;fail:	cpu_buf->tracing = 0;	cpu_buf->backtrace_aborted++;	return;} /* * This serves to avoid cpu buffer overflow, and makes sure * the task mortuary progresses * * By using schedule_delayed_work_on and then schedule_delayed_work * we guarantee this will stay on the correct cpu */static void wq_sync_buffer(struct work_struct *work){	struct oprofile_cpu_buffer *b =		container_of(work, struct oprofile_cpu_buffer, work.work);	if (b->cpu != smp_processor_id()) {		printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",		       smp_processor_id(), b->cpu); 		if (!cpu_online(b->cpu)) {			cancel_delayed_work(&b->work);			return;		}	}	sync_buffer(b->cpu); 	/* don't re-add the work if we're shutting down */	if (work_enabled)		schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);}