A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 11:11:45 -04:00
Code Issues Projects Releases Packages Wiki Activity

perf tool: Precise mode requires exclude_guest

Browse source 
Summary of events per Peter:

  "Intel PEBS in VT-x context uses the DS address as a guest linear address,
  even though its programmed by the host as a host linear address. This
  either results in guest memory corruption and or the hardware faulting and
  'crashing' the virtual machine.  Therefore we have to disable PEBS on VT-x
  enter and re-enable on VT-x exit, enforcing a strict exclude_guest.

  AMB IBS does work but doesn't currently support exclude_* at all,
  setting an exclude_* bit will make it fail."

This patch handles userspace perf command, setting the exclude_guest
attribute if precise mode is requested, but only if a user has not
specified a request for guest or host only profiling (G or H attribute).

Kernel side AMD currently ignores all exclude_* bits, so there is no impact
to existing IBS code paths. Robert Richter has a patch where IBS code will
return EINVAL if an exclude_* bit is set. When this goes in it means use
of :p on AMD with IBS will first fail with EINVAL (because exclude_guest
will be set). Then the existing fallback code within perf will unset
exclude_guest and try again. The second attempt will succeed if the CPU
supports IBS profiling.

Signed-off-by: David Ahern <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Acked-by: Robert Richter <[email protected]>
Tested-by: Robert Richter <[email protected]>
Reviewed-by: Robert Richter <[email protected]>
Cc: Avi Kivity <[email protected]>
Cc: Gleb Natapov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Robert Richter <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
This commit is contained in:
David Ahern 2012-09-13 14:59:13 -06:00 • committed by Arnaldo Carvalho de Melo
commit 1342798cc1
1 changed files with 3 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

3
tools/perf/util/parse-events.c
View file

@ -690,6 +690,9 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
eH = 0;
} else if (*str == 'p') {
precise++;
/* use of precise requires exclude_guest */
if (!exclude_GH)
eG = 1;
} else
break;