linux-kernel - [ 013/105] sparc64: Fix bit twiddling in sparc_pmu_enable

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Message-Id: <20121028231541.060088859@decadent.org.uk>
Date:	Sun, 28 Oct 2012 23:15:49 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 013/105] sparc64: Fix bit twiddling in sparc_pmu_enable_event().

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

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

From: "David S. Miller" <davem@...emloft.net>

[ Upstream commit e793d8c6740f8fe704fa216e95685f4d92c4c4b9 ]

There was a serious disconnect in the logic happening in
sparc_pmu_disable_event() vs. sparc_pmu_enable_event().

Event disable is implemented by programming a NOP event into the PCR.

However, event enable was not reversing this operation.  Instead, it
was setting the User/Priv/Hypervisor trace enable bits.

That's not sparc_pmu_enable_event()'s job, that's what
sparc_pmu_enable() and sparc_pmu_disable() do .

The intent of sparc_pmu_enable_event() is clear, since it first clear
out the event type encoding field.  So fix this by OR'ing in the event
encoding rather than the trace enable bits.

Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/sparc/kernel/perf_event.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 5331ae1..3c8f220 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -555,11 +555,13 @@ static u64 nop_for_index(int idx)

 static inline void sparc_pmu_enable_event(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc, int idx)
 {
-	u64 val, mask = mask_for_index(idx);
+	u64 enc, val, mask = mask_for_index(idx);
+
+	enc = perf_event_get_enc(cpuc->events[idx]);

 	val = cpuc->pcr;
 	val &= ~mask;
-	val |= hwc->config;
+	val |= event_encoding(enc, idx);
 	cpuc->pcr = val;

 	pcr_ops->write(cpuc->pcr);

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