mirrors/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2025-10-31 16:48:26 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

ftrace, perf: Add support to use function tracepoint in perf

Browse source 
Adding perf registration support for the ftrace function event,
so it is now possible to register it via perf interface.

The perf_event struct statically contains ftrace_ops as a handle
for function tracer. The function tracer is registered/unregistered
in open/close actions.

To be efficient, we enable/disable ftrace_ops each time the traced
process is scheduled in/out (via TRACE_REG_PERF_(ADD|DELL) handlers).
This way tracing is enabled only when the process is running.
Intentionally using this way instead of the event's hw state
PERF_HES_STOPPED, which would not disable the ftrace_ops.

It is now possible to use function trace within perf commands
like:

  perf record -e ftrace:function ls
  perf stat -e ftrace:function ls

Allowed only for root.

Link: http://lkml.kernel.org/r/1329317514-8131-6-git-send-email-jolsa@redhat.com

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa 2012-02-15 15:51:52 +01:00 committed by Steven Rostedt
parent e59a0bff3e
commit ced39002f5
5 changed files with 109 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/perf_event.h
View file

@ -859,6 +859,9 @@ struct perf_event {
#ifdef CONFIG_EVENT_TRACING
struct ftrace_event_call *tp_event;
struct event_filter *filter;
#ifdef CONFIG_FUNCTION_TRACER
struct ftrace_ops ftrace_ops;
#endif
#endif
#ifdef CONFIG_CGROUP_PERF

11
kernel/trace/trace.h
View file

@ -595,6 +595,8 @@ static inline int ftrace_trace_task(struct task_struct *task)
static inline int ftrace_is_dead(void) { return 0; }
#endif
int ftrace_event_is_function(struct ftrace_event_call *call);
/*
* struct trace_parser - servers for reading the user input separated by spaces
* @cont: set if the input is not complete - no final space char was found
@ -832,4 +834,13 @@ extern const char *__stop___trace_bprintk_fmt[];
FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
#include "trace_entries.h"
#ifdef CONFIG_PERF_EVENTS
#ifdef CONFIG_FUNCTION_TRACER
int perf_ftrace_event_register(struct ftrace_event_call *call,
enum trace_reg type, void *data);
#else
#define perf_ftrace_event_register NULL
#endif /* CONFIG_FUNCTION_TRACER */
#endif /* CONFIG_PERF_EVENTS */
#endif /* _LINUX_KERNEL_TRACE_H */

6
kernel/trace/trace_entries.h
View file

@ -55,7 +55,7 @@
/*
* Function trace entry - function address and parent function address:
*/
FTRACE_ENTRY(function, ftrace_entry,
FTRACE_ENTRY_REG(function, ftrace_entry,
TRACE_FN,
@ -64,7 +64,9 @@ FTRACE_ENTRY(function, ftrace_entry,
__field( unsigned long, parent_ip )
),
F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip)
F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip),
perf_ftrace_event_register
);
/* Function call entry */

86
kernel/trace/trace_event_perf.c
View file

@ -24,6 +24,11 @@ static int total_ref_count;
static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
struct perf_event *p_event)
{
/* The ftrace function trace is allowed only for root. */
if (ftrace_event_is_function(tp_event) &&
perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
return -EPERM;
/* No tracing, just counting, so no obvious leak */
if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
return 0;
@ -250,3 +255,84 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
return raw_data;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
#ifdef CONFIG_FUNCTION_TRACER
static void
perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_entry *entry;
struct hlist_head *head;
struct pt_regs regs;
int rctx;
#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
sizeof(u64)) - sizeof(u32))
BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
perf_fetch_caller_regs(&regs);
entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
if (!entry)
return;
entry->ip = ip;
entry->parent_ip = parent_ip;
head = this_cpu_ptr(event_function.perf_events);
perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
1, &regs, head);
#undef ENTRY_SIZE
}
static int perf_ftrace_function_register(struct perf_event *event)
{
struct ftrace_ops *ops = &event->ftrace_ops;
ops->flags |= FTRACE_OPS_FL_CONTROL;
ops->func = perf_ftrace_function_call;
return register_ftrace_function(ops);
}
static int perf_ftrace_function_unregister(struct perf_event *event)
{
struct ftrace_ops *ops = &event->ftrace_ops;
return unregister_ftrace_function(ops);
}
static void perf_ftrace_function_enable(struct perf_event *event)
{
ftrace_function_local_enable(&event->ftrace_ops);
}
static void perf_ftrace_function_disable(struct perf_event *event)
{
ftrace_function_local_disable(&event->ftrace_ops);
}
int perf_ftrace_event_register(struct ftrace_event_call *call,
enum trace_reg type, void *data)
{
switch (type) {
case TRACE_REG_REGISTER:
case TRACE_REG_UNREGISTER:
break;
case TRACE_REG_PERF_REGISTER:
case TRACE_REG_PERF_UNREGISTER:
return 0;
case TRACE_REG_PERF_OPEN:
return perf_ftrace_function_register(data);
case TRACE_REG_PERF_CLOSE:
return perf_ftrace_function_unregister(data);
case TRACE_REG_PERF_ADD:
perf_ftrace_function_enable(data);
return 0;
case TRACE_REG_PERF_DEL:
perf_ftrace_function_disable(data);
return 0;
}
return -EINVAL;
}
#endif /* CONFIG_FUNCTION_TRACER */

5
kernel/trace/trace_export.c
View file

@ -184,4 +184,9 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
FTRACE_ENTRY_REG(call, struct_name, etype, \
PARAMS(tstruct), PARAMS(print), NULL)
int ftrace_event_is_function(struct ftrace_event_call *call)
{
return call == &event_function;
}
#include "trace_entries.h"