Patch "powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9" has been added to the 4.12-stable tree

Patch "powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-perf-fix-sdar_mode-value-for-continous-sampling-on-power9.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 20dd4c624d25156d5ec3345bbb690b98175ef879 Mon Sep 17 00:00:00 2001
From: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Date: Tue, 11 Jul 2017 16:27:49 +0530
Subject: powerpc/perf: Fix SDAR_MODE value for continous sampling on Power9

From: Madhavan Srinivasan <maddy@linux.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@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;


Patches currently in stable-queue which might be from maddy@linux.vnet.ibm.com are

queue-4.12/powerpc-perf-fix-sdar_mode-value-for-continous-sampling-on-power9.patch