lkml.org 
[lkml]   [2012]   [Feb]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 5/7] ftrace, perf: Add support to use function tracepoint in perf
    On Wed, Feb 15, 2012 at 03:51:52PM +0100, Jiri Olsa wrote:
    > 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.
    >
    > Signed-off-by: Jiri Olsa <jolsa@redhat.com>

    Acked-by: Frederic Weisbecker <fweisbec@gmail.com>

    > ---
    > include/linux/perf_event.h | 3 +
    > kernel/trace/trace.h | 11 +++++
    > kernel/trace/trace_entries.h | 6 ++-
    > kernel/trace/trace_event_perf.c | 86 +++++++++++++++++++++++++++++++++++++++
    > kernel/trace/trace_export.c | 5 ++
    > 5 files changed, 109 insertions(+), 2 deletions(-)
    >
    > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    > index 412b790..92a056f 100644
    > --- a/include/linux/perf_event.h
    > +++ b/include/linux/perf_event.h
    > @@ -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
    > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
    > index 638476a..76a1c50 100644
    > --- a/kernel/trace/trace.h
    > +++ b/kernel/trace/trace.h
    > @@ -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 */
    > diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
    > index 9336590..47db7ed 100644
    > --- a/kernel/trace/trace_entries.h
    > +++ b/kernel/trace/trace_entries.h
    > @@ -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 */
    > diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
    > index d72af0b..fdeeb5c 100644
    > --- a/kernel/trace/trace_event_perf.c
    > +++ b/kernel/trace/trace_event_perf.c
    > @@ -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 */
    > diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
    > index f74de86..a3dbee6 100644
    > --- a/kernel/trace/trace_export.c
    > +++ b/kernel/trace/trace_export.c
    > @@ -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"
    > --
    > 1.7.1
    >


    \
     
     \ /
      Last update: 2012-02-15 17:05    [W:0.036 / U:4.044 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site