linux-kernel - [PATCH 3.18 14/85] perf/x86/intel/uncore: Correct fixed counter index check in generic code

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Message-Id: <20180807172357.883218197@linuxfoundation.org>
Date:   Tue,  7 Aug 2018 20:51:16 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kan Liang <kan.liang@...el.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        acme@...nel.org, eranian@...gle.com,
        Ingo Molnar <mingo@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 3.18 14/85] perf/x86/intel/uncore: Correct fixed counter index check in generic code

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

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

From: Kan Liang <kan.liang@...el.com>

[ Upstream commit 4749f8196452eeb73cf2086a6a9705bae479d33d ]

There is no index which is bigger than UNCORE_PMC_IDX_FIXED. The only
exception is client IMC uncore, which has been specially handled.
For generic code, it is not correct to use >= to check fixed counter.
The code quality issue will bring problem when a new counter index is
introduced.

Signed-off-by: Kan Liang <kan.liang@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: acme@...nel.org
Cc: eranian@...gle.com
Link: http://lkml.kernel.org/r/1525371913-10597-3-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/cpu/perf_event_intel_uncore.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -175,7 +175,7 @@ void uncore_perf_event_update(struct int
 	u64 prev_count, new_count, delta;
 	int shift;
 
-	if (event->hw.idx >= UNCORE_PMC_IDX_FIXED)
+	if (event->hw.idx == UNCORE_PMC_IDX_FIXED)
 		shift = 64 - uncore_fixed_ctr_bits(box);
 	else
 		shift = 64 - uncore_perf_ctr_bits(box);