linux-kernel - [PATCH] perf/core: Don't allow grouping events from different hw pmus

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Message-ID: <20221122080326.228-1-ravi.bangoria@amd.com>
Date:   Tue, 22 Nov 2022 13:33:26 +0530
From:   Ravi Bangoria <ravi.bangoria@....com>
To:     <peterz@...radead.org>
CC:     <ravi.bangoria@....com>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <jolsa@...hat.com>, <namhyung@...nel.org>,
        <bp@...en8.de>, <linux-perf-users@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <sandipan.das@....com>,
        <ananth.narayan@....com>, <santosh.shukla@....com>
Subject: [PATCH] perf/core: Don't allow grouping events from different hw pmus

Event group from different hw pmus does not make sense and thus perf
has never allowed it. However, with recent rewrite that restriction
has been inadvertently removed. Fix it.

Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>
---
 kernel/events/core.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5f262f91cd31..4ee866ef075d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12499,15 +12499,21 @@ SYSCALL_DEFINE5(perf_event_open,
 			 * perf_event_pmu_context.
 			 */
 			pmu = group_leader->pmu_ctx->pmu;
-		} else if (!is_software_event(event) &&
-			is_software_event(group_leader) &&
-			(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
-			/*
-			 * In case the group is a pure software group, and we
-			 * try to add a hardware event, move the whole group to
-			 * the hardware context.
-			 */
-			move_group = 1;
+		} else if (!is_software_event(event)) {
+			if (is_software_event(group_leader) &&
+			    (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
+				/*
+				 * In case the group is a pure software group, and we
+				 * try to add a hardware event, move the whole group to
+				 * the hardware context.
+				 */
+				move_group = 1;
+			}
+
+			/* Don't allow group of multiple hw events from different pmus */
+			if (!in_software_context(group_leader) &&
+			    group_leader->pmu_ctx->pmu != pmu)
+				goto err_locked;
 		}
 	}
 
-- 
2.38.1