Coresight: ETMv4: Prevent TRCRSCTLR0&1 from being accessed

1. TRCRSCTLRn - Resource Selection Control Registers n=0~1 are reserved,
   we shouldn't access them.
2. The max number of 'n' here is defined in TRCIDR4.NUMRSPAIR whoes value
   indicates the number of resource selection *pairs*, and 0 indicates
   one resource selection pair, 1 indicates two pairs, and so on ...

So, the total number of resource selection control registers which we can
access is (TRCIDR4.NUMRSPAIR * 2)
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-etm4x.c

@@ -136,7 +136,9 @@ static void etm4_enable_hw(void *info)
 		writel_relaxed(drvdata->cntr_val[i],
 			       drvdata->base + TRCCNTVRn(i));
 	}
-	for (i = 0; i < drvdata->nr_resource; i++)
+
+	/* Resource selector pair 0 is always implemented and reserved */
+	for (i = 2; i < drvdata->nr_resource * 2; i++)
 		writel_relaxed(drvdata->res_ctrl[i],
 			       drvdata->base + TRCRSCTLRn(i));
 
@@ -489,8 +491,9 @@ static ssize_t reset_store(struct device *dev,
 		drvdata->cntr_val[i] = 0x0;
 	}
 
-	drvdata->res_idx = 0x0;
-	for (i = 0; i < drvdata->nr_resource; i++)
+	/* Resource selector pair 0 is always implemented and reserved */
+	drvdata->res_idx = 0x2;
+	for (i = 2; i < drvdata->nr_resource * 2; i++)
 		drvdata->res_ctrl[i] = 0x0;
 
 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
@@ -1732,7 +1735,7 @@ static ssize_t res_idx_store(struct device *dev,
 	if (kstrtoul(buf, 16, &val))
 		return -EINVAL;
 	/* Resource selector pair 0 is always implemented and reserved */
-	if ((val == 0) || (val >= drvdata->nr_resource))
+	if (val < 2 || val >= drvdata->nr_resource * 2)
 		return -EINVAL;
 
 	/*
@@ -2416,8 +2419,13 @@ static void etm4_init_arch_data(void *info)
 	drvdata->nr_addr_cmp = BMVAL(etmidr4, 0, 3);
 	/* NUMPC, bits[15:12] number of PE comparator inputs for tracing */
 	drvdata->nr_pe_cmp = BMVAL(etmidr4, 12, 15);
-	/* NUMRSPAIR, bits[19:16] the number of resource pairs for tracing */
-	drvdata->nr_resource = BMVAL(etmidr4, 16, 19);
+	/*
+	 * NUMRSPAIR, bits[19:16]
+	 * The number of resource pairs conveyed by the HW starts at 0, i.e a
+	 * value of 0x0 indicate 1 resource pair, 0x1 indicate two and so on.
+	 * As such add 1 to the value of NUMRSPAIR for a better representation.
+	 */
+	drvdata->nr_resource = BMVAL(etmidr4, 16, 19) + 1;
 	/*
 	 * NUMSSCC, bits[23:20] the number of single-shot
 	 * comparator control for tracing
@@ -2504,6 +2512,8 @@ static void etm4_init_default_data(struct etmv4_drvdata *drvdata)
 		drvdata->cntr_val[i] = 0x0;
 	}
 
+	/* Resource selector pair 0 is always implemented and reserved */
+	drvdata->res_idx = 0x2;
 	for (i = 2; i < drvdata->nr_resource * 2; i++)
 		drvdata->res_ctrl[i] = 0x0;