[PATCH v8 02/13] coresight: etm4x: fix underflow for usage of (nrseqstate - 1)
Yeoreum Yun
yeoreum.yun at arm.com
Mon Jun 29 01:59:55 PDT 2026
According to IHI006H Embedded Trace Macrocell Architecture
Specification[0], TRCSEQEVR<n> is implemented only when
TRCIDR5.NUMSEQSTATE is 0b100, in which case n ranges from 0 to 2;
otherwise, TRCIDR5.NUMSEQSTATE is 0b000.
IOW, the number of usage in the initialisation or setting
TRCSEQEVR<n> with drvdata->nrseqstate - 1 in the loop could make
underflow issue when TRCIDR5.NUMSEQSTATE is 0b000.
Therefore, introduce nr_seq_ctrls field and untie it from nrseqstate.
As part of this introduce ETM_MAX_SEQ_TRANSITIONS macro and
apply nr_seq_ctrls and above macro to TRCSEQEVR<n> relevant fields setup.
Link: https://developer.arm.com/documentation/ihi0064/latest/ [0]
Fixes: 2e1cdfe184b5 ("coresight-etm4x: Adding CoreSight ETM4x driver")
Suggested-by: Leo Yan <leo.yan at arm.com>
Suggested-by: Suzuki K Poulose <suzuki.poulose at arm.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun at arm.com>
---
drivers/hwtracing/coresight/coresight-etm4x-cfg.c | 2 +-
drivers/hwtracing/coresight/coresight-etm4x-core.c | 9 ++++++---
drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 6 ++++--
drivers/hwtracing/coresight/coresight-etm4x.h | 7 +++++--
4 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
index c302072b293a..e1a59b434505 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
@@ -76,7 +76,7 @@ static int etm4_cfg_map_reg_offset(struct etmv4_drvdata *drvdata,
} else if ((offset & GENMASK(11, 4)) == TRCSEQEVRn(0)) {
/* sequencer state control registers */
idx = (offset & GENMASK(3, 0)) / 4;
- if (idx < ETM_MAX_SEQ_STATES) {
+ if (idx < ETM_MAX_SEQ_TRANSITIONS) {
reg_csdev->driver_regval = &drvcfg->seq_ctrl[idx];
err = 0;
}
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 1e3b0344dc00..1884960cfe6f 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -542,7 +542,8 @@ 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++)
+
+ for (i = 0; i < drvdata->nr_seq_ctrls; i++)
etm4x_relaxed_write32(csa, config->seq_ctrl[i], TRCSEQEVRn(i));
if (drvdata->nrseqstate) {
etm4x_relaxed_write32(csa, config->seq_rst, TRCSEQRSTEVR);
@@ -1508,6 +1509,8 @@ static void etm4_init_arch_data(void *info)
drvdata->lpoverride = (etmidr5 & TRCIDR5_LPOVERRIDE) && (!drvdata->skip_power_up);
/* NUMSEQSTATE, bits[27:25] number of sequencer states implemented */
drvdata->nrseqstate = FIELD_GET(TRCIDR5_NUMSEQSTATE_MASK, etmidr5);
+ if (drvdata->nrseqstate)
+ drvdata->nr_seq_ctrls = ETM_MAX_SEQ_TRANSITIONS;
/* NUMCNTR, bits[30:28] number of counters available for tracing */
drvdata->nr_cntr = FIELD_GET(TRCIDR5_NUMCNTR_MASK, etmidr5);
@@ -1896,7 +1899,7 @@ static int etm4_cpu_save(struct coresight_device *csdev)
if (drvdata->nr_pe_cmp)
state->trcvipcssctlr = etm4x_read32(csa, TRCVIPCSSCTLR);
- for (i = 0; i < drvdata->nrseqstate - 1; i++)
+ for (i = 0; i < drvdata->nr_seq_ctrls; i++)
state->trcseqevr[i] = etm4x_read32(csa, TRCSEQEVRn(i));
if (drvdata->nrseqstate) {
@@ -2009,7 +2012,7 @@ static void etm4_cpu_restore(struct coresight_device *csdev)
if (drvdata->nr_pe_cmp)
etm4x_relaxed_write32(csa, state->trcvipcssctlr, TRCVIPCSSCTLR);
- for (i = 0; i < drvdata->nrseqstate - 1; i++)
+ for (i = 0; i < drvdata->nr_seq_ctrls; i++)
etm4x_relaxed_write32(csa, state->trcseqevr[i], TRCSEQEVRn(i));
if (drvdata->nrseqstate) {
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
index e9eeea6240d5..cc6cdd3ae29d 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
@@ -223,7 +223,7 @@ static ssize_t reset_store(struct device *dev,
config->vipcssctlr = 0x0;
/* Disable seq events */
- for (i = 0; i < drvdata->nrseqstate-1; i++)
+ for (i = 0; i < drvdata->nr_seq_ctrls; i++)
config->seq_ctrl[i] = 0x0;
config->seq_rst = 0x0;
config->seq_state = 0x0;
@@ -1395,9 +1395,11 @@ 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->nr_seq_ctrls)
+ return -ENOTSUPP;
if (kstrtoul(buf, 16, &val))
return -EINVAL;
- if (val >= drvdata->nrseqstate - 1)
+ if (val >= drvdata->nr_seq_ctrls)
return -EINVAL;
/*
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 89d81ce4e04e..84db8b97c98a 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -614,6 +614,7 @@ static inline u32 etm4_res_sel_pair(u8 res_sel_idx)
#define ETM_MAX_NR_PE 8
#define ETMv4_MAX_CNTR 4
#define ETM_MAX_SEQ_STATES 4
+#define ETM_MAX_SEQ_TRANSITIONS 3
#define ETM_MAX_EXT_INP_SEL 4
#define ETM_MAX_EXT_INP 256
#define ETM_MAX_EXT_OUT 4
@@ -877,7 +878,7 @@ struct etmv4_config {
u32 vipcssctlr;
u8 seq_idx;
u8 syncfreq;
- u32 seq_ctrl[ETM_MAX_SEQ_STATES];
+ u32 seq_ctrl[ETM_MAX_SEQ_TRANSITIONS];
u32 seq_rst;
u32 seq_state;
u8 cntr_idx;
@@ -928,7 +929,7 @@ struct etmv4_save_state {
u32 trcvissctlr;
u32 trcvipcssctlr;
- u32 trcseqevr[ETM_MAX_SEQ_STATES];
+ u32 trcseqevr[ETM_MAX_SEQ_TRANSITIONS];
u32 trcseqrstevr;
u32 trcseqstr;
u32 trcextinselr;
@@ -981,6 +982,7 @@ struct etmv4_save_state {
* @numcidc: Number of contextID comparators.
* @numvmidc: Number of VMID comparators.
* @nrseqstate: The number of sequencer states that are implemented.
+ * @nr_seq_ctrls: The number of sequence state transition control registers.
* @nr_event: Indicates how many events the trace unit support.
* @nr_resource:The number of resource selection pairs available for tracing.
* @nr_ss_cmp: Number of single-shot comparator controls that are available.
@@ -1046,6 +1048,7 @@ struct etmv4_drvdata {
u8 numextinsel;
u8 numvmidc;
u8 nrseqstate;
+ u8 nr_seq_ctrls;
u8 nr_event;
u8 nr_resource;
u8 nr_ss_cmp;
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
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