Messages in this thread | | | Date | Fri, 7 Aug 2009 22:21:06 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH] perfcounters: Support for ftrace event records sampling |
| |
On Fri, Aug 07, 2009 at 10:09:07PM +0200, Peter Zijlstra wrote: > On Fri, 2009-08-07 at 12:38 +0200, Peter Zijlstra wrote: > > > +static void ftrace_profile_##call(proto) \ > > > +{ \ > > > + struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\ > > > + struct ftrace_event_call *event_call = &event_##call; \ > > > + extern void perf_tpcounter_event(int, u64, u64, void *, int); \ > > > + struct ftrace_raw_##call *entry; \ > > > + u64 __addr = 0, __count = 1; \ > > > + unsigned long irq_flags; \ > > > + int __entry_size; \ > > > + int __data_size; \ > > > + int pc; \ > > > + \ > > > + local_save_flags(irq_flags); \ > > > + pc = preempt_count(); \ > > > + \ > > > + __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \ > > > + __entry_size = __data_size + sizeof(*entry); \ > > > + \ > > > + do { \ > > > + char raw_data[__entry_size]; \ > > > + struct trace_entry *ent; \ > > > + \ > > > + entry = (struct ftrace_raw_##call *)raw_data; \ > > > + ent = &entry->ent; \ > > > + tracing_generic_entry_update(ent, irq_flags, pc); \ > > > + ent->type = event_call->id; \ > > > + \ > > > + tstruct \ > > > + \ > > > + { assign; } \ > > > + \ > > > + perf_tpcounter_event(event_call->id, __addr, __count, entry,\ > > > + __entry_size); \ > > > + } while (0); \ > > > + \ > > > +} > > > > ok, so the one concern I have here is that the data needs to fit on the > > stack. What if someone puts a large string in the data? > > Also, how NMI safe is all that?
Everything is allocated in the stack. It's NMI safe AFAICS, am I missing something?
| |