3.7-stable review patch. If anyone has any objections, please let me know.
------------------ From: David Ahern <[email protected]> commit a706d965dcfdff73bf2bad1c300f8119900714c7 upstream. This patch is brought to you by the letter 'H'. Commit 20b279 breaks compatiblity with older perf binaries when run with precise modifier (:p or :pp) by requiring the exclude_guest attribute to be set. Older binaries default exclude_guest to 0 (ie., wanting guest-based samples) unless host only profiling is requested (:H modifier). The workaround for older binaries is to add H to the modifier list (e.g., -e cycles:ppH - toggles exclude_guest to 1). This was deemed unacceptable by Linus: https://lkml.org/lkml/2012/12/12/570 Between family in town and the fresh snow in Breckenridge there is no time left to be working on the proper fix for this over the holidays. In the New Year I have more pressing problems to resolve -- like some memory leaks in perf which are proving to be elusive -- although the aforementioned snow is probably why they are proving to be elusive. Either way I do not have any spare time to work on this and from the time I have managed to spend on it the solution is more difficult than just moving to a new exclude_guest flag (does not work) or flipping the logic to include_guest (which is not as trivial as one would think). So, two options: silently force exclude_guest on as suggested by Gleb which means no impact to older perf binaries or revert the original patch which caused the breakage. This patch does the latter -- reverts the original patch that introduced the regression. The problem can be revisited in the future as time allows. Signed-off-by: David Ahern <[email protected]> Cc: Avi Kivity <[email protected]> Cc: Gleb Natapov <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[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]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/cpu/perf_event.c | 6 ------ 1 file changed, 6 deletions(-) --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -340,9 +340,6 @@ int x86_setup_perfctr(struct perf_event /* BTS is currently only allowed for user-mode. */ if (!attr->exclude_kernel) return -EOPNOTSUPP; - - if (!attr->exclude_guest) - return -EOPNOTSUPP; } hwc->config |= config; @@ -385,9 +382,6 @@ int x86_pmu_hw_config(struct perf_event if (event->attr.precise_ip) { int precise = 0; - if (!event->attr.exclude_guest) - return -EOPNOTSUPP; - /* Support for constant skid */ if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) { precise++; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
