linux/kernel/trace/trace_mmiotrace.c
Steven Rostedt 38697053fa ftrace: preempt disable over interrupt disable
With the new ring buffer infrastructure in ftrace, I'm trying to make
ftrace a little more light weight.

This patch converts a lot of the local_irq_save/restore into
preempt_disable/enable.  The original preempt count in a lot of cases
has to be sent in as a parameter so that it can be recorded correctly.
Some places were recording it incorrectly before anyway.

This is also laying the ground work to make ftrace a little bit
more reentrant, and remove all locking. The function tracers must
still protect from reentrancy.

Note: All the function tracers must be careful when using preempt_disable.
  It must do the following:

  resched = need_resched();
  preempt_disable_notrace();
  [...]
  if (resched)
	preempt_enable_no_resched_notrace();
  else
	preempt_enable_notrace();

The reason is that if this function traces schedule() itself, the
preempt_enable_notrace() will cause a schedule, which will lead
us into a recursive failure.

If we needed to reschedule before calling preempt_disable, we
should have already scheduled. Since we did not, this is most
likely that we should not and are probably inside a schedule
function.

If resched was not set, we still need to catch the need resched
flag being set when preemption was off and the if case at the
end will catch that for us.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14 10:39:09 +02:00

377 lines
8.9 KiB
C

/*
* Memory mapped I/O tracing
*
* Copyright (C) 2008 Pekka Paalanen <pq@iki.fi>
*/
#define DEBUG 1
#include <linux/kernel.h>
#include <linux/mmiotrace.h>
#include <linux/pci.h>
#include "trace.h"
struct header_iter {
struct pci_dev *dev;
};
static struct trace_array *mmio_trace_array;
static bool overrun_detected;
static void mmio_reset_data(struct trace_array *tr)
{
int cpu;
overrun_detected = false;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
}
static void mmio_trace_init(struct trace_array *tr)
{
pr_debug("in %s\n", __func__);
mmio_trace_array = tr;
if (tr->ctrl) {
mmio_reset_data(tr);
enable_mmiotrace();
}
}
static void mmio_trace_reset(struct trace_array *tr)
{
pr_debug("in %s\n", __func__);
if (tr->ctrl)
disable_mmiotrace();
mmio_reset_data(tr);
mmio_trace_array = NULL;
}
static void mmio_trace_ctrl_update(struct trace_array *tr)
{
pr_debug("in %s\n", __func__);
if (tr->ctrl) {
mmio_reset_data(tr);
enable_mmiotrace();
} else {
disable_mmiotrace();
}
}
static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
{
int ret = 0;
int i;
resource_size_t start, end;
const struct pci_driver *drv = pci_dev_driver(dev);
/* XXX: incomplete checks for trace_seq_printf() return value */
ret += trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
dev->bus->number, dev->devfn,
dev->vendor, dev->device, dev->irq);
/*
* XXX: is pci_resource_to_user() appropriate, since we are
* supposed to interpret the __ioremap() phys_addr argument based on
* these printed values?
*/
for (i = 0; i < 7; i++) {
pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
ret += trace_seq_printf(s, " %llx",
(unsigned long long)(start |
(dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
}
for (i = 0; i < 7; i++) {
pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
ret += trace_seq_printf(s, " %llx",
dev->resource[i].start < dev->resource[i].end ?
(unsigned long long)(end - start) + 1 : 0);
}
if (drv)
ret += trace_seq_printf(s, " %s\n", drv->name);
else
ret += trace_seq_printf(s, " \n");
return ret;
}
static void destroy_header_iter(struct header_iter *hiter)
{
if (!hiter)
return;
pci_dev_put(hiter->dev);
kfree(hiter);
}
static void mmio_pipe_open(struct trace_iterator *iter)
{
struct header_iter *hiter;
struct trace_seq *s = &iter->seq;
trace_seq_printf(s, "VERSION 20070824\n");
hiter = kzalloc(sizeof(*hiter), GFP_KERNEL);
if (!hiter)
return;
hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, NULL);
iter->private = hiter;
}
/* XXX: This is not called when the pipe is closed! */
static void mmio_close(struct trace_iterator *iter)
{
struct header_iter *hiter = iter->private;
destroy_header_iter(hiter);
iter->private = NULL;
}
static unsigned long count_overruns(struct trace_iterator *iter)
{
int cpu;
unsigned long cnt = 0;
/* FIXME: */
#if 0
for_each_online_cpu(cpu) {
cnt += iter->overrun[cpu];
iter->overrun[cpu] = 0;
}
#endif
(void)cpu;
return cnt;
}
static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
char __user *ubuf, size_t cnt, loff_t *ppos)
{
ssize_t ret;
struct header_iter *hiter = iter->private;
struct trace_seq *s = &iter->seq;
unsigned long n;
n = count_overruns(iter);
if (n) {
/* XXX: This is later than where events were lost. */
trace_seq_printf(s, "MARK 0.000000 Lost %lu events.\n", n);
if (!overrun_detected)
pr_warning("mmiotrace has lost events.\n");
overrun_detected = true;
goto print_out;
}
if (!hiter)
return 0;
mmio_print_pcidev(s, hiter->dev);
hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, hiter->dev);
if (!hiter->dev) {
destroy_header_iter(hiter);
iter->private = NULL;
}
print_out:
ret = trace_seq_to_user(s, ubuf, cnt);
return (ret == -EBUSY) ? 0 : ret;
}
static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct trace_mmiotrace_rw *field;
struct mmiotrace_rw *rw;
struct trace_seq *s = &iter->seq;
unsigned long long t = ns2usecs(iter->ts);
unsigned long usec_rem = do_div(t, 1000000ULL);
unsigned secs = (unsigned long)t;
int ret = 1;
trace_assign_type(field, entry);
rw = &field->rw;
switch (rw->opcode) {
case MMIO_READ:
ret = trace_seq_printf(s,
"R %d %lu.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
rw->width, secs, usec_rem, rw->map_id,
(unsigned long long)rw->phys,
rw->value, rw->pc, 0);
break;
case MMIO_WRITE:
ret = trace_seq_printf(s,
"W %d %lu.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
rw->width, secs, usec_rem, rw->map_id,
(unsigned long long)rw->phys,
rw->value, rw->pc, 0);
break;
case MMIO_UNKNOWN_OP:
ret = trace_seq_printf(s,
"UNKNOWN %lu.%06lu %d 0x%llx %02x,%02x,%02x 0x%lx %d\n",
secs, usec_rem, rw->map_id,
(unsigned long long)rw->phys,
(rw->value >> 16) & 0xff, (rw->value >> 8) & 0xff,
(rw->value >> 0) & 0xff, rw->pc, 0);
break;
default:
ret = trace_seq_printf(s, "rw what?\n");
break;
}
if (ret)
return TRACE_TYPE_HANDLED;
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t mmio_print_map(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct trace_mmiotrace_map *field;
struct mmiotrace_map *m;
struct trace_seq *s = &iter->seq;
unsigned long long t = ns2usecs(iter->ts);
unsigned long usec_rem = do_div(t, 1000000ULL);
unsigned secs = (unsigned long)t;
int ret;
trace_assign_type(field, entry);
m = &field->map;
switch (m->opcode) {
case MMIO_PROBE:
ret = trace_seq_printf(s,
"MAP %lu.%06lu %d 0x%llx 0x%lx 0x%lx 0x%lx %d\n",
secs, usec_rem, m->map_id,
(unsigned long long)m->phys, m->virt, m->len,
0UL, 0);
break;
case MMIO_UNPROBE:
ret = trace_seq_printf(s,
"UNMAP %lu.%06lu %d 0x%lx %d\n",
secs, usec_rem, m->map_id, 0UL, 0);
break;
default:
ret = trace_seq_printf(s, "map what?\n");
break;
}
if (ret)
return TRACE_TYPE_HANDLED;
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct print_entry *print = (struct print_entry *)entry;
const char *msg = print->buf;
struct trace_seq *s = &iter->seq;
unsigned long long t = ns2usecs(iter->ts);
unsigned long usec_rem = do_div(t, 1000000ULL);
unsigned secs = (unsigned long)t;
int ret;
/* The trailing newline must be in the message. */
ret = trace_seq_printf(s, "MARK %lu.%06lu %s", secs, usec_rem, msg);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
return TRACE_TYPE_HANDLED;
}
static enum print_line_t mmio_print_line(struct trace_iterator *iter)
{
switch (iter->ent->type) {
case TRACE_MMIO_RW:
return mmio_print_rw(iter);
case TRACE_MMIO_MAP:
return mmio_print_map(iter);
case TRACE_PRINT:
return mmio_print_mark(iter);
default:
return TRACE_TYPE_HANDLED; /* ignore unknown entries */
}
}
static struct tracer mmio_tracer __read_mostly =
{
.name = "mmiotrace",
.init = mmio_trace_init,
.reset = mmio_trace_reset,
.pipe_open = mmio_pipe_open,
.close = mmio_close,
.read = mmio_read,
.ctrl_update = mmio_trace_ctrl_update,
.print_line = mmio_print_line,
};
__init static int init_mmio_trace(void)
{
return register_tracer(&mmio_tracer);
}
device_initcall(init_mmio_trace);
static void __trace_mmiotrace_rw(struct trace_array *tr,
struct trace_array_cpu *data,
struct mmiotrace_rw *rw)
{
struct ring_buffer_event *event;
struct trace_mmiotrace_rw *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, preempt_count());
entry->ent.type = TRACE_MMIO_RW;
entry->rw = *rw;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
trace_wake_up();
}
void mmio_trace_rw(struct mmiotrace_rw *rw)
{
struct trace_array *tr = mmio_trace_array;
struct trace_array_cpu *data = tr->data[smp_processor_id()];
__trace_mmiotrace_rw(tr, data, rw);
}
static void __trace_mmiotrace_map(struct trace_array *tr,
struct trace_array_cpu *data,
struct mmiotrace_map *map)
{
struct ring_buffer_event *event;
struct trace_mmiotrace_map *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, preempt_count());
entry->ent.type = TRACE_MMIO_MAP;
entry->map = *map;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
trace_wake_up();
}
void mmio_trace_mapping(struct mmiotrace_map *map)
{
struct trace_array *tr = mmio_trace_array;
struct trace_array_cpu *data;
preempt_disable();
data = tr->data[smp_processor_id()];
__trace_mmiotrace_map(tr, data, map);
preempt_enable();
}
int mmio_trace_printk(const char *fmt, va_list args)
{
return trace_vprintk(0, fmt, args);
}