[PATCH v5 02/12] coresight: etm4x: fix underflow for nrseqstate

[Yeoreum Yun <yeoreum.yun@arm.com>]

TCRSEQEVR<n> is implemented only when TCRIDR5.NUMSEQSTATE is 0b100,
in which case n ranges from 0 to 2; otherwise, TCRIDR5.NUMSEQSTATE is 0b000.

Therefore, drvdata->nrseqstate should be checked before entering the loop.

Link: https://developer.arm.com/documentation/ihi0064/latest/ [0]
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 .../hwtracing/coresight/coresight-etm4x-core.c | 18 ++++++++++--------
 .../coresight/coresight-etm4x-sysfs.c          |  2 ++
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 74b7063d130e..ba5b8b423bd4 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -544,9 +544,11 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 	etm4x_relaxed_write32(csa, config->vissctlr, TRCVISSCTLR);
 	if (drvdata->nr_pe_cmp)
 		etm4x_relaxed_write32(csa, config->vipcssctlr, TRCVIPCSSCTLR);
-	for (i = 0; i < drvdata->nrseqstate - 1; i++)
-		etm4x_relaxed_write32(csa, config->seq_ctrl[i], TRCSEQEVRn(i));
+
 	if (drvdata->nrseqstate) {
+		for (i = 0; i < drvdata->nrseqstate - 1; i++)
+			etm4x_relaxed_write32(csa, config->seq_ctrl[i], TRCSEQEVRn(i));
+
 		etm4x_relaxed_write32(csa, config->seq_rst, TRCSEQRSTEVR);
 		etm4x_relaxed_write32(csa, config->seq_state, TRCSEQSTR);
 	}
@@ -1927,10 +1929,10 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 	if (drvdata->nr_pe_cmp)
 		state->trcvipcssctlr = etm4x_read32(csa, TRCVIPCSSCTLR);
 
-	for (i = 0; i < drvdata->nrseqstate - 1; i++)
-		state->trcseqevr[i] = etm4x_read32(csa, TRCSEQEVRn(i));
-
 	if (drvdata->nrseqstate) {
+		for (i = 0; i < drvdata->nrseqstate - 1; i++)
+			state->trcseqevr[i] = etm4x_read32(csa, TRCSEQEVRn(i));
+
 		state->trcseqrstevr = etm4x_read32(csa, TRCSEQRSTEVR);
 		state->trcseqstr = etm4x_read32(csa, TRCSEQSTR);
 	}
@@ -2058,10 +2060,10 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 	if (drvdata->nr_pe_cmp)
 		etm4x_relaxed_write32(csa, state->trcvipcssctlr, TRCVIPCSSCTLR);
 
-	for (i = 0; i < drvdata->nrseqstate - 1; i++)
-		etm4x_relaxed_write32(csa, state->trcseqevr[i], TRCSEQEVRn(i));
-
 	if (drvdata->nrseqstate) {
+		for (i = 0; i < drvdata->nrseqstate - 1; i++)
+			etm4x_relaxed_write32(csa, state->trcseqevr[i], TRCSEQEVRn(i));
+
 		etm4x_relaxed_write32(csa, state->trcseqrstevr, TRCSEQRSTEVR);
 		etm4x_relaxed_write32(csa, state->trcseqstr, TRCSEQSTR);
 	}
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
index e9eeea6240d5..d866dcfa2a36 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
@@ -1395,6 +1395,8 @@ static ssize_t seq_idx_store(struct device *dev,
 	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
 	struct etmv4_config *config = &drvdata->config;
 
+	if (!drvdata->nrseqstate)
+		return -EINVAL;
 	if (kstrtoul(buf, 16, &val))
 		return -EINVAL;
 	if (val >= drvdata->nrseqstate - 1)
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}