linux-kernel - [PATCH 4.12 057/196] powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9

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Date:   Tue, 25 Jul 2017 12:20:56 -0700
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>
Subject: [PATCH 4.12 057/196] powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9

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

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

From: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>

commit 20dd4c624d25156d5ec3345bbb690b98175ef879 upstream.

In case of continous sampling (non-marked), the code currently
sets MMCRA[SDAR_MODE] to 0b01 (Update on TLB miss) for Power9 DD1.

On DD2 and later it copies the sdar_mode value from the event code,
which for most events is 0b00 (No updates).

However we must set a non-zero value for SDAR_MODE when doing
continuous sampling, so honor the event code, unless it's zero, in
which case we use use 0b01 (Update on TLB miss).

Fixes: 78b4416aa249 ("powerpc/perf: Handle sdar_mode for marked event in power9")
Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/perf/isa207-common.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/powerpc/perf/isa207-common.c
+++ b/arch/powerpc/perf/isa207-common.c
@@ -90,13 +90,15 @@ static void mmcra_sdar_mode(u64 event, u
 	 *	MMCRA[SDAR_MODE] will be set to 0b01
 	 * For rest
 	 *	MMCRA[SDAR_MODE] will be set from event code.
+	 *      If sdar_mode from event is zero, default to 0b01. Hardware
+	 *      requires that we set a non-zero value.
 	 */
 	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
 		if (is_event_marked(event) || (*mmcra & MMCRA_SAMPLE_ENABLE))
 			*mmcra &= MMCRA_SDAR_MODE_NO_UPDATES;
-		else if (!cpu_has_feature(CPU_FTR_POWER9_DD1))
+		else if (!cpu_has_feature(CPU_FTR_POWER9_DD1) && p9_SDAR_MODE(event))
 			*mmcra |=  p9_SDAR_MODE(event) << MMCRA_SDAR_MODE_SHIFT;
-		else if (cpu_has_feature(CPU_FTR_POWER9_DD1))
+		else
 			*mmcra |= MMCRA_SDAR_MODE_TLB;
 	} else
 		*mmcra |= MMCRA_SDAR_MODE_TLB;