Frederic Weisbecker wrote: > Events that trigger overflows by interrupting a context can > use get_irq_regs() or task_pt_regs() to retrieve the state > when the event triggered. But this is not the case for some > other class of events like trace events as tracepoints are > executed in the same context than the code that triggered > the event. > > It means we need a different api to capture the regs there, > namely we need a hot snapshot to get the most important > informations for perf: the instruction pointer to get the > event origin, the frame pointer for the callchain, the code > segment for user_mode() tests (we always use __KERNEL_CS as > trace events always occur from the kernel) and the eflags > for further purposes. > > Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: H. Peter Anvin <hpa@xxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Paul Mackerras <paulus@xxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > Cc: Jason Baron <jbaron@xxxxxxxxxx> > Cc: Archs <linux-arch@xxxxxxxxxxxxxxx> > --- > arch/x86/kernel/cpu/perf_event.c | 12 ++++++++++ > arch/x86/kernel/dumpstack.h | 15 +++++++++++++ > include/linux/perf_event.h | 42 +++++++++++++++++++++++++++++++++++++- > kernel/perf_event.c | 5 ++++ > 4 files changed, 73 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c > index 641ccb9..274d0cd 100644 > --- a/arch/x86/kernel/cpu/perf_event.c > +++ b/arch/x86/kernel/cpu/perf_event.c > @@ -1662,6 +1662,18 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) > return entry; > } > > +void perf_arch_save_regs(struct pt_regs *regs, unsigned long ip, int skip) Hmm, why would you call it 'save_regs' ? It seems that this function is just for fixing registers instead of saving it into somewhere... Thank you, -- Masami Hiramatsu e-mail: mhiramat@xxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html