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tracing: add support for userspace stacktraces in tracing/iter_ctrl

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Impact: add new (default-off) tracing visualization feature

Usage example:

 mount -t debugfs nodev /sys/kernel/debug
 cd /sys/kernel/debug/tracing
 echo userstacktrace >iter_ctrl
 echo sched_switch >current_tracer
 echo 1 >tracing_enabled
 .... run application ...
 echo 0 >tracing_enabled

Then read one of 'trace','latency_trace','trace_pipe'.

To get the best output you can compile your userspace programs with
frame pointers (at least glibc + the app you are tracing).

Signed-off-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Török Edwin
2008-11-22 13:28:47 +02:00
committed by Ingo Molnar
parent a0a70c735e
commit 02b67518e2
5 changed files with 171 additions and 1 deletions
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93
kernel/trace/trace.c
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@ -275,6 +275,7 @@ static const char *trace_options[] = {
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
NULL
};
@ -918,6 +919,44 @@ void __trace_stack(struct trace_array *tr,
ftrace_trace_stack(tr, data, flags, skip, preempt_count());
}
static void ftrace_trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags, int pc)
{
struct userstack_entry *entry;
struct stack_trace trace;
struct ring_buffer_event *event;
unsigned long irq_flags;
if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
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, flags, pc);
entry->ent.type = TRACE_USER_STACK;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = 0;
trace.entries = entry->caller;
save_stack_trace_user(&trace);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
}
void __trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags)
{
ftrace_trace_userstack(tr, data, flags, preempt_count());
}
static void
ftrace_trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3,
@ -941,6 +980,7 @@ ftrace_trace_special(void *__tr, void *__data,
entry->arg3 = arg3;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, irq_flags, 4, pc);
ftrace_trace_userstack(tr, data, irq_flags, pc);
trace_wake_up();
}
@ -979,6 +1019,7 @@ tracing_sched_switch_trace(struct trace_array *tr,
entry->next_cpu = task_cpu(next);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 5, pc);
ftrace_trace_userstack(tr, data, flags, pc);
}
void
@ -1008,6 +1049,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
entry->next_cpu = task_cpu(wakee);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 6, pc);
ftrace_trace_userstack(tr, data, flags, pc);
trace_wake_up();
}
@ -1387,6 +1429,31 @@ seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
return ret;
}
static int
seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
unsigned long sym_flags)
{
int ret = 1;
unsigned i;
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
unsigned long ip = entry->caller[i];
if (ip == ULONG_MAX || !ret)
break;
if (i)
ret = trace_seq_puts(s, " <- ");
if (!ip) {
ret = trace_seq_puts(s, "??");
continue;
}
if (ret /*&& (sym_flags & TRACE_ITER_SYM_ADDR)*/)
ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
}
return ret;
}
static void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
@ -1702,6 +1769,16 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
field->line);
break;
}
case TRACE_USER_STACK: {
struct userstack_entry *field;
trace_assign_type(field, entry);
seq_print_userip_objs(field, s, sym_flags);
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
break;
}
default:
trace_seq_printf(s, "Unknown type %d\n", entry->type);
}
@ -1853,6 +1930,19 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
field->line);
break;
}
case TRACE_USER_STACK: {
struct userstack_entry *field;
trace_assign_type(field, entry);
ret = seq_print_userip_objs(field, s, sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_putc(s, '\n');
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
}
return TRACE_TYPE_HANDLED;
}
@ -1912,6 +2002,7 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;
@ -2000,6 +2091,7 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;
@ -2054,6 +2146,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
break;
}
case TRACE_SPECIAL:
case TRACE_USER_STACK:
case TRACE_STACK: {
struct special_entry *field;