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linux-next/drivers/oprofile/cpu_buffer.c
Carl Love f4156d1cd1 powerpc/cell/oprofile: Avoid double vfree of profile buffer
If an error occurs on opcontrol start, the event and per cpu buffers
are released.  If later opcontrol shutdown is called then the free
function will be called again to free buffers that no longer
exist.  This results in a kernel oops.  The following changes
prevent the call to delete buffers that don't exist.

Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-08-26 10:24:46 +10:00

308 lines
7.0 KiB
C

/**
* @file cpu_buffer.c
*
* @remark Copyright 2002 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon <levon@movementarian.org>
*
* 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/vmalloc.h>
#include <linux/errno.h>
#include "event_buffer.h"
#include "cpu_buffer.h"
#include "buffer_sync.h"
#include "oprof.h"
DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
static void wq_sync_buffer(struct work_struct *work);
#define DEFAULT_TIMER_EXPIRE (HZ / 10)
static int work_enabled;
void free_cpu_buffers(void)
{
int i;
for_each_online_cpu(i) {
vfree(per_cpu(cpu_buffer, i).buffer);
per_cpu(cpu_buffer, i).buffer = NULL;
}
}
int alloc_cpu_buffers(void)
{
int i;
unsigned long buffer_size = fs_cpu_buffer_size;
for_each_online_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
cpu_to_node(i));
if (!b->buffer)
goto fail;
b->last_task = NULL;
b->last_is_kernel = -1;
b->tracing = 0;
b->buffer_size = buffer_size;
b->tail_pos = 0;
b->head_pos = 0;
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(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)
{
int i;
work_enabled = 0;
for_each_online_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);
cancel_delayed_work(&b->work);
}
flush_scheduled_work();
}
/* Resets the cpu buffer to a sane state. */
void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf)
{
/* reset these to invalid values; the next sample
* collected will populate the buffer with proper
* values to initialize the buffer
*/
cpu_buf->last_is_kernel = -1;
cpu_buf->last_task = NULL;
}
/* compute number of available slots in cpu_buffer queue */
static unsigned long nr_available_slots(struct oprofile_cpu_buffer const * b)
{
unsigned long head = b->head_pos;
unsigned long tail = b->tail_pos;
if (tail > head)
return (tail - head) - 1;
return tail + (b->buffer_size - head) - 1;
}
static void increment_head(struct oprofile_cpu_buffer * b)
{
unsigned long new_head = b->head_pos + 1;
/* Ensure anything written to the slot before we
* increment is visible */
wmb();
if (new_head < b->buffer_size)
b->head_pos = new_head;
else
b->head_pos = 0;
}
static inline void
add_sample(struct oprofile_cpu_buffer * cpu_buf,
unsigned long pc, unsigned long event)
{
struct op_sample * entry = &cpu_buf->buffer[cpu_buf->head_pos];
entry->eip = pc;
entry->event = event;
increment_head(cpu_buf);
}
static inline void
add_code(struct oprofile_cpu_buffer * buffer, unsigned long value)
{
add_sample(buffer, ESCAPE_CODE, value);
}
/* This must be safe from any context. It's safe writing here
* because of the head/tail separation of the writer and reader
* of the CPU buffer.
*
* 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 int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc,
int is_kernel, unsigned long event)
{
struct task_struct * task;
cpu_buf->sample_received++;
if (pc == ESCAPE_CODE) {
cpu_buf->sample_invalid_eip++;
return 0;
}
if (nr_available_slots(cpu_buf) < 3) {
cpu_buf->sample_lost_overflow++;
return 0;
}
is_kernel = !!is_kernel;
task = current;
/* notice a switch from user->kernel or vice versa */
if (cpu_buf->last_is_kernel != is_kernel) {
cpu_buf->last_is_kernel = is_kernel;
add_code(cpu_buf, is_kernel);
}
/* notice a task switch */
if (cpu_buf->last_task != task) {
cpu_buf->last_task = task;
add_code(cpu_buf, (unsigned long)task);
}
add_sample(cpu_buf, pc, event);
return 1;
}
static int oprofile_begin_trace(struct oprofile_cpu_buffer * cpu_buf)
{
if (nr_available_slots(cpu_buf) < 4) {
cpu_buf->sample_lost_overflow++;
return 0;
}
add_code(cpu_buf, CPU_TRACE_BEGIN);
cpu_buf->tracing = 1;
return 1;
}
static void oprofile_end_trace(struct oprofile_cpu_buffer * cpu_buf)
{
cpu_buf->tracing = 0;
}
void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
unsigned long event, int is_kernel)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
if (!backtrace_depth) {
log_sample(cpu_buf, pc, is_kernel, event);
return;
}
if (!oprofile_begin_trace(cpu_buf))
return;
/* if log_sample() fail we can't backtrace since we lost the source
* of this event */
if (log_sample(cpu_buf, pc, is_kernel, event))
oprofile_ops.backtrace(regs, backtrace_depth);
oprofile_end_trace(cpu_buf);
}
void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
{
int is_kernel = !user_mode(regs);
unsigned long pc = profile_pc(regs);
oprofile_add_ext_sample(pc, regs, event, is_kernel);
}
void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
log_sample(cpu_buf, pc, is_kernel, event);
}
void oprofile_add_trace(unsigned long pc)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
if (!cpu_buf->tracing)
return;
if (nr_available_slots(cpu_buf) < 1) {
cpu_buf->tracing = 0;
cpu_buf->sample_lost_overflow++;
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) {
cpu_buf->tracing = 0;
cpu_buf->backtrace_aborted++;
return;
}
add_sample(cpu_buf, pc, 0);
}
/*
* 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("WQ on CPU%d, prefer CPU%d\n",
smp_processor_id(), b->cpu);
}
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);
}