linux-kernel - [tip: perf/urgent] perf/x86/intel: Set PERF_ATTACH_SCHED

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Message-ID: <161459377043.20312.676489427209789411.tip-bot2@tip-bot2>
Date:   Mon, 01 Mar 2021 10:16:10 -0000
From:   "tip-bot2 for Kan Liang" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Kan Liang <kan.liang@...ux.intel.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf/x86/intel: Set PERF_ATTACH_SCHED_CB for large
 PEBS and LBR

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     a8abc881981762631a22568d5e4b2c0ce4aeb15c
Gitweb:        https://git.kernel.org/tip/a8abc881981762631a22568d5e4b2c0ce4aeb15c
Author:        Kan Liang <kan.liang@...ux.intel.com>
AuthorDate:    Mon, 30 Nov 2020 11:38:41 -08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 01 Mar 2021 11:02:19 +01:00

perf/x86/intel: Set PERF_ATTACH_SCHED_CB for large PEBS and LBR

To supply a PID/TID for large PEBS, it requires flushing the PEBS buffer
in a context switch.

For normal LBRs, a context switch can flip the address space and LBR
entries are not tagged with an identifier, we need to wipe the LBR, even
for per-cpu events.

For LBR callstack, save/restore the stack is required during a context
switch.

Set PERF_ATTACH_SCHED_CB for the event with large PEBS & LBR.

Fixes: 9c964efa4330 ("perf/x86/intel: Drain the PEBS buffer during context switches")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20201130193842.10569-2-kan.liang@linux.intel.com
---
 arch/x86/events/intel/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 5bac48d..7bbb5bb 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3662,8 +3662,10 @@ static int intel_pmu_hw_config(struct perf_event *event)
 		if (!(event->attr.freq || (event->attr.wakeup_events && !event->attr.watermark))) {
 			event->hw.flags |= PERF_X86_EVENT_AUTO_RELOAD;
 			if (!(event->attr.sample_type &
-			      ~intel_pmu_large_pebs_flags(event)))
+			      ~intel_pmu_large_pebs_flags(event))) {
 				event->hw.flags |= PERF_X86_EVENT_LARGE_PEBS;
+				event->attach_state |= PERF_ATTACH_SCHED_CB;
+			}
 		}
 		if (x86_pmu.pebs_aliases)
 			x86_pmu.pebs_aliases(event);
@@ -3676,6 +3678,7 @@ static int intel_pmu_hw_config(struct perf_event *event)
 		ret = intel_pmu_setup_lbr_filter(event);
 		if (ret)
 			return ret;
+		event->attach_state |= PERF_ATTACH_SCHED_CB;
 
 		/*
 		 * BTS is set up earlier in this path, so don't account twice