Based on patches from Andi Kleen.

When printing PT instruction traces with perf script it is rather useful
to see some indentation for the call tree. This patch adds a new
callindent field to perf script that prints spaces for the function call
stack depth.

We already have code to track the function call stack for PT, that we
can reuse with minor modifications.

The resulting output is not quite as nice as ftrace yet, but a lot
better than what was there before.

Note there are some corner cases when the thread stack gets code
confused and prints incorrect indentation. Even with that it is fairly
useful.

When displaying kernel code traces it is recommended to run as root, as
otherwise perf doesn't understand the kernel addresses properly, and may
not reset the call stack correctly on kernel boundaries.

Example output:

	sudo perf-with-kcore record eg2 -a -e intel_pt// -- sleep 1
	sudo perf-with-kcore script eg2 --ns -F callindent,time,comm,pid,sym,ip,addr,flags,cpu --itrace=cre | less
	...
         swapper     0 [000]  5830.389116586:   call        irq_exit                                                     ffffffff8104d620 smp_call_function_single_interrupt+0x30 => ffffffff8107e720 irq_exit
         swapper     0 [000]  5830.389116586:   call            idle_cpu                                                 ffffffff8107e769 irq_exit+0x49 => ffffffff810a3970 idle_cpu
         swapper     0 [000]  5830.389116586:   return          idle_cpu                                                 ffffffff810a39b7 idle_cpu+0x47 => ffffffff8107e76e irq_exit
         swapper     0 [000]  5830.389116586:   call            tick_nohz_irq_exit                                       ffffffff8107e7bd irq_exit+0x9d => ffffffff810f2fc0 tick_nohz_irq_exit
         swapper     0 [000]  5830.389116919:   call                __tick_nohz_idle_enter                               ffffffff810f2fe0 tick_nohz_irq_exit+0x20 => ffffffff810f28d0 __tick_nohz_idle_enter
         swapper     0 [000]  5830.389116919:   call                    ktime_get                                        ffffffff810f28f1 __tick_nohz_idle_enter+0x21 => ffffffff810e9ec0 ktime_get
         swapper     0 [000]  5830.389116919:   call                        read_tsc                                     ffffffff810e9ef6 ktime_get+0x36 => ffffffff81035070 read_tsc
         swapper     0 [000]  5830.389116919:   return                      read_tsc                                     ffffffff81035084 read_tsc+0x14 => ffffffff810e9efc ktime_get
         swapper     0 [000]  5830.389116919:   return                  ktime_get                                        ffffffff810e9f46 ktime_get+0x86 => ffffffff810f28f6 __tick_nohz_idle_enter
         swapper     0 [000]  5830.389116919:   call                    sched_clock_idle_sleep_event                     ffffffff810f290b __tick_nohz_idle_enter+0x3b => ffffffff810a7380 sched_clock_idle_sleep_event
         swapper     0 [000]  5830.389116919:   call                        sched_clock_cpu                              ffffffff810a738b sched_clock_idle_sleep_event+0xb => ffffffff810a72e0 sched_clock_cpu
         swapper     0 [000]  5830.389116919:   call                            sched_clock                              ffffffff810a734d sched_clock_cpu+0x6d => ffffffff81035750 sched_clock
         swapper     0 [000]  5830.389116919:   call                                native_sched_clock                   ffffffff81035754 sched_clock+0x4 => ffffffff81035640 native_sched_clock
         swapper     0 [000]  5830.389116919:   return                              native_sched_clock                   ffffffff8103568c native_sched_clock+0x4c => ffffffff81035759 sched_clock
         swapper     0 [000]  5830.389116919:   return                          sched_clock                              ffffffff8103575c sched_clock+0xc => ffffffff810a7352 sched_clock_cpu
         swapper     0 [000]  5830.389116919:   return                      sched_clock_cpu                              ffffffff810a7356 sched_clock_cpu+0x76 => ffffffff810a7390 sched_clock_idle_sleep_event
         swapper     0 [000]  5830.389116919:   return                  sched_clock_idle_sleep_event                     ffffffff810a7391 sched_clock_idle_sleep_event+0x11 => ffffffff810f2910 __tick_nohz_idle_enter
	...

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1466689258-28493-4-git-send-email-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>