linux-kernel - [PATCH 4.20 221/352] powerpc/perf: Fix thresholding counter data for unknown type

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Message-Id: <20190211141901.290154563@linuxfoundation.org>
Date:   Mon, 11 Feb 2019 15:17:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.20 221/352] powerpc/perf: Fix thresholding counter data for unknown type

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 17cfccc91545682513541924245abb876d296063 ]

MMCRA[34:36] and MMCRA[38:44] expose the thresholding counter value.
Thresholding counter can be used to count latency cycles such as
load miss to reload. But threshold counter value is not relevant
when the sampled instruction type is unknown or reserved. Patch to
fix the thresholding counter value to zero when sampled instruction
type is unknown or reserved.

Fixes: 170a315f41c6('powerpc/perf: Support to export MMCRA[TEC*] field to userspace')
Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/perf/isa207-common.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c
index 177de814286f..6a2f65d3d088 100644
--- a/arch/powerpc/perf/isa207-common.c
+++ b/arch/powerpc/perf/isa207-common.c
@@ -226,8 +226,13 @@ void isa207_get_mem_weight(u64 *weight)
 	u64 mmcra = mfspr(SPRN_MMCRA);
 	u64 exp = MMCRA_THR_CTR_EXP(mmcra);
 	u64 mantissa = MMCRA_THR_CTR_MANT(mmcra);
+	u64 sier = mfspr(SPRN_SIER);
+	u64 val = (sier & ISA207_SIER_TYPE_MASK) >> ISA207_SIER_TYPE_SHIFT;
 
-	*weight = mantissa << (2 * exp);
+	if (val == 0 || val == 7)
+		*weight = 0;
+	else
+		*weight = mantissa << (2 * exp);
 }
 
 int isa207_get_constraint(u64 event, unsigned long *maskp, unsigned long *valp)
-- 
2.19.1