linux-kernel - [PATCH AUTOSEL 4.4 12/20] coresight: tpiu: Fix disabling timeouts

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Message-ID: <20180915013502.180110-12-alexander.levin@microsoft.com>
Date:   Sat, 15 Sep 2018 01:35:12 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Robin Murphy <robin.murphy@....com>,
        Robert Walker <robert.walker@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.4 12/20] coresight: tpiu: Fix disabling timeouts

From: Robin Murphy <robin.murphy@....com>

[ Upstream commit ccff2dfaceaca4517432f5c149594215fe9098cc ]

Probing the TPIU driver under UBSan triggers an out-of-bounds shift
warning in coresight_timeout():

...
[    5.677530] UBSAN: Undefined behaviour in drivers/hwtracing/coresight/coresight.c:929:16
[    5.685542] shift exponent 64 is too large for 64-bit type 'long unsigned int'
...

On closer inspection things are exponentially out of whack because we're
passing a bitmask where a bit number should be. Amusingly, it seems that
both calls will find their expected values by sheer luck and appear to
succeed: 1 << FFCR_FON_MAN ends up at bit 64 which whilst undefined
evaluates as zero in practice, while 1 << FFSR_FT_STOPPED finds bit 2
(TCPresent) which apparently is usually tied high.

Following the examples of other drivers, define separate FOO and FOO_BIT
macros for masks vs. indices, and put things right.

CC: Robert Walker <robert.walker@....com>
CC: Mike Leach <mike.leach@...aro.org>
CC: Mathieu Poirier <mathieu.poirier@...aro.org>
Fixes: 11595db8e17f ("coresight: Fix disabling of CoreSight TPIU")
Signed-off-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/hwtracing/coresight/coresight-tpiu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c
index 22e10b7d505d..fe3a2b19a5db 100644
--- a/drivers/hwtracing/coresight/coresight-tpiu.c
+++ b/drivers/hwtracing/coresight/coresight-tpiu.c
@@ -46,8 +46,9 @@
 
 /** register definition **/
 /* FFSR - 0x300 */
-#define FFSR_FT_STOPPED		BIT(1)
+#define FFSR_FT_STOPPED_BIT	1
 /* FFCR - 0x304 */
+#define FFCR_FON_MAN_BIT	6
 #define FFCR_FON_MAN		BIT(6)
 #define FFCR_STOP_FI		BIT(12)
 
@@ -93,9 +94,9 @@ static void tpiu_disable_hw(struct tpiu_drvdata *drvdata)
 	/* Generate manual flush */
 	writel_relaxed(FFCR_STOP_FI | FFCR_FON_MAN, drvdata->base + TPIU_FFCR);
 	/* Wait for flush to complete */
-	coresight_timeout(drvdata->base, TPIU_FFCR, FFCR_FON_MAN, 0);
+	coresight_timeout(drvdata->base, TPIU_FFCR, FFCR_FON_MAN_BIT, 0);
 	/* Wait for formatter to stop */
-	coresight_timeout(drvdata->base, TPIU_FFSR, FFSR_FT_STOPPED, 1);
+	coresight_timeout(drvdata->base, TPIU_FFSR, FFSR_FT_STOPPED_BIT, 1);
 
 	CS_LOCK(drvdata->base);
 }
-- 
2.17.1