coresight: etm4x: Fix input validation for sysfs.

A number of issues are fixed relating to sysfs input validation:-

1) bb_ctrl_store() - incorrect compare of bit select field to absolute
value. Reworked per ETMv4 specification.
2) seq_event_store() - incorrect mask value - register has two
event values.
3) cyc_threshold_store() - must mask with max before checking min
otherwise wrapped values can set illegal value below min.
4) res_ctrl_store() - update to mask off all res0 bits.
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Fixes: a77de263 ("coresight: etm4x: moving sysFS entries to a dedicated file")
Cc: stable <stable@vger.kernel.org> # 4.9+
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20191104181251.26732-6-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-etm4x-sysfs.c

@@ -652,10 +652,13 @@ static ssize_t cyc_threshold_store(struct device *dev,
 
 	if (kstrtoul(buf, 16, &val))
 		return -EINVAL;
+
+	/* mask off max threshold before checking min value */
+	val &= ETM_CYC_THRESHOLD_MASK;
 	if (val < drvdata->ccitmin)
 		return -EINVAL;
 
-	config->ccctlr = val & ETM_CYC_THRESHOLD_MASK;
+	config->ccctlr = val;
 	return size;
 }
 static DEVICE_ATTR_RW(cyc_threshold);
@@ -686,14 +689,16 @@ static ssize_t bb_ctrl_store(struct device *dev,
 		return -EINVAL;
 	if (!drvdata->nr_addr_cmp)
 		return -EINVAL;
+
 	/*
-	 * Bit[7:0] selects which address range comparator is used for
-	 * branch broadcast control.
+	 * Bit[8] controls include(1) / exclude(0), bits[0-7] select
+	 * individual range comparators. If include then at least 1
+	 * range must be selected.
 	 */
-	if (BMVAL(val, 0, 7) > drvdata->nr_addr_cmp)
+	if ((val & BIT(8)) && (BMVAL(val, 0, 7) == 0))
 		return -EINVAL;
 
-	config->bb_ctrl = val;
+	config->bb_ctrl = val & GENMASK(8, 0);
 	return size;
 }
 static DEVICE_ATTR_RW(bb_ctrl);
@@ -1324,8 +1329,8 @@ static ssize_t seq_event_store(struct device *dev,
 
 	spin_lock(&drvdata->spinlock);
 	idx = config->seq_idx;
-	/* RST, bits[7:0] */
-	config->seq_ctrl[idx] = val & 0xFF;
+	/* Seq control has two masks B[15:8] F[7:0] */
+	config->seq_ctrl[idx] = val & 0xFFFF;
 	spin_unlock(&drvdata->spinlock);
 	return size;
 }
@@ -1580,7 +1585,7 @@ static ssize_t res_ctrl_store(struct device *dev,
 	if (idx % 2 != 0)
 		/* PAIRINV, bit[21] */
 		val &= ~BIT(21);
-	config->res_ctrl[idx] = val;
+	config->res_ctrl[idx] = val & GENMASK(21, 0);
 	spin_unlock(&drvdata->spinlock);
 	return size;
 }