ftrace, perf: Add support to use function tracepoint in perf
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>
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ced39002f5
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@ -859,6 +859,9 @@ struct perf_event {
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#ifdef CONFIG_EVENT_TRACING
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struct ftrace_event_call *tp_event;
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struct event_filter *filter;
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#ifdef CONFIG_FUNCTION_TRACER
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struct ftrace_ops ftrace_ops;
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#endif
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#endif
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#ifdef CONFIG_CGROUP_PERF
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@ -595,6 +595,8 @@ static inline int ftrace_trace_task(struct task_struct *task)
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static inline int ftrace_is_dead(void) { return 0; }
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#endif
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int ftrace_event_is_function(struct ftrace_event_call *call);
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/*
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* struct trace_parser - servers for reading the user input separated by spaces
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* @cont: set if the input is not complete - no final space char was found
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@ -832,4 +834,13 @@ extern const char *__stop___trace_bprintk_fmt[];
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FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
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#include "trace_entries.h"
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#ifdef CONFIG_PERF_EVENTS
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#ifdef CONFIG_FUNCTION_TRACER
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int perf_ftrace_event_register(struct ftrace_event_call *call,
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enum trace_reg type, void *data);
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#else
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#define perf_ftrace_event_register NULL
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#endif /* CONFIG_FUNCTION_TRACER */
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#endif /* CONFIG_PERF_EVENTS */
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#endif /* _LINUX_KERNEL_TRACE_H */
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@ -55,7 +55,7 @@
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/*
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* Function trace entry - function address and parent function address:
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*/
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FTRACE_ENTRY(function, ftrace_entry,
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FTRACE_ENTRY_REG(function, ftrace_entry,
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TRACE_FN,
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@ -64,7 +64,9 @@ FTRACE_ENTRY(function, ftrace_entry,
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__field( unsigned long, parent_ip )
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),
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F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip)
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F_printk(" %lx <-- %lx", __entry->ip, __entry->parent_ip),
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perf_ftrace_event_register
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);
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/* Function call entry */
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@ -24,6 +24,11 @@ static int total_ref_count;
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static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
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struct perf_event *p_event)
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{
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/* The ftrace function trace is allowed only for root. */
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if (ftrace_event_is_function(tp_event) &&
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perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
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return -EPERM;
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/* No tracing, just counting, so no obvious leak */
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if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
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return 0;
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@ -250,3 +255,84 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
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return raw_data;
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}
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EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
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#ifdef CONFIG_FUNCTION_TRACER
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static void
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perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
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{
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struct ftrace_entry *entry;
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struct hlist_head *head;
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struct pt_regs regs;
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int rctx;
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#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
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sizeof(u64)) - sizeof(u32))
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BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
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perf_fetch_caller_regs(®s);
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entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
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if (!entry)
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return;
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entry->ip = ip;
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entry->parent_ip = parent_ip;
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head = this_cpu_ptr(event_function.perf_events);
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perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
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1, ®s, head);
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#undef ENTRY_SIZE
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}
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static int perf_ftrace_function_register(struct perf_event *event)
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{
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struct ftrace_ops *ops = &event->ftrace_ops;
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ops->flags |= FTRACE_OPS_FL_CONTROL;
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ops->func = perf_ftrace_function_call;
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return register_ftrace_function(ops);
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}
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static int perf_ftrace_function_unregister(struct perf_event *event)
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{
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struct ftrace_ops *ops = &event->ftrace_ops;
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return unregister_ftrace_function(ops);
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}
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static void perf_ftrace_function_enable(struct perf_event *event)
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{
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ftrace_function_local_enable(&event->ftrace_ops);
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}
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static void perf_ftrace_function_disable(struct perf_event *event)
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{
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ftrace_function_local_disable(&event->ftrace_ops);
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}
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int perf_ftrace_event_register(struct ftrace_event_call *call,
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enum trace_reg type, void *data)
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{
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switch (type) {
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case TRACE_REG_REGISTER:
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case TRACE_REG_UNREGISTER:
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break;
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case TRACE_REG_PERF_REGISTER:
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case TRACE_REG_PERF_UNREGISTER:
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return 0;
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case TRACE_REG_PERF_OPEN:
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return perf_ftrace_function_register(data);
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case TRACE_REG_PERF_CLOSE:
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return perf_ftrace_function_unregister(data);
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case TRACE_REG_PERF_ADD:
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perf_ftrace_function_enable(data);
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return 0;
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case TRACE_REG_PERF_DEL:
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perf_ftrace_function_disable(data);
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return 0;
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}
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return -EINVAL;
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}
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#endif /* CONFIG_FUNCTION_TRACER */
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@ -184,4 +184,9 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
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FTRACE_ENTRY_REG(call, struct_name, etype, \
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PARAMS(tstruct), PARAMS(print), NULL)
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int ftrace_event_is_function(struct ftrace_event_call *call)
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{
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return call == &event_function;
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}
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#include "trace_entries.h"
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