[PATCH v2 3/5] coresight: etm4x: fix inconsistencies with sysfs configration

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

The current ETM4x configuration via sysfs can lead to the following
inconsistencies:

  - If a configuration is modified via sysfs while a perf session is
    active, the running configuration may differ between before
    a sched-out and after a subsequent sched-in.

  - If a perf session and sysfs session tries to enable concurrently,
    configuration from configfs could be corrupted.

  - There is chance to corrupt drvdata->config if perf session tries
    to enabled among handling cscfg_csdev_disable_active_config()
    in etm4_disable_sysfs().

To resolve these inconsistencies, the configuration should be separated into:

  - active_config, which is applied configuration for the current session
  - config, which stores the settings configured via sysfs.

and apply configuration from configfs after taking a mode.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 .../hwtracing/coresight/coresight-etm4x-cfg.c |  2 +-
 .../coresight/coresight-etm4x-core.c          | 74 ++++++++++++-------
 drivers/hwtracing/coresight/coresight-etm4x.h |  2 +
 3 files changed, 49 insertions(+), 29 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
index d14d7c8a23e5..0553771d04e7 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
@@ -47,7 +47,7 @@ static int etm4_cfg_map_reg_offset(struct etmv4_drvdata *drvdata,
 				   struct cscfg_regval_csdev *reg_csdev, u32 offset)
 {
 	int err = -EINVAL, idx;
-	struct etmv4_config *drvcfg = &drvdata->config;
+	struct etmv4_config *drvcfg = &drvdata->active_config;
 	u32 off_mask;
 
 	if (((offset >= TRCEVENTCTL0R) && (offset <= TRCVIPCSSCTLR)) ||
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index b7abb171f523..c7b4a0b85106 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -245,6 +245,9 @@ void etm4_release_trace_id(struct etmv4_drvdata *drvdata)
 
 struct etm4_enable_arg {
 	struct etmv4_drvdata *drvdata;
+	unsigned long cfg_hash;
+	int preset;
+	u8 trace_id;
 	int rc;
 };
 
@@ -270,10 +273,11 @@ static void etm4x_prohibit_trace(struct etmv4_drvdata *drvdata)
 static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
 {
 	u64 trfcr = drvdata->trfcr;
+	struct etmv4_config *config = &drvdata->active_config;
 
-	if (drvdata->config.mode & ETM_MODE_EXCL_KERN)
+	if (config->mode & ETM_MODE_EXCL_KERN)
 		trfcr &= ~TRFCR_EL1_ExTRE;
-	if (drvdata->config.mode & ETM_MODE_EXCL_USER)
+	if (config->mode & ETM_MODE_EXCL_USER)
 		trfcr &= ~TRFCR_EL1_E0TRE;
 
 	return trfcr;
@@ -281,7 +285,7 @@ static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
 
 /*
  * etm4x_allow_trace - Allow CPU tracing in the respective ELs,
- * as configured by the drvdata->config.mode for the current
+ * as configured by the drvdata->active_config.mode for the current
  * session. Even though we have TRCVICTLR bits to filter the
  * trace in the ELs, it doesn't prevent the ETM from generating
  * a packet (e.g, TraceInfo) that might contain the addresses from
@@ -292,12 +296,13 @@ static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
 static void etm4x_allow_trace(struct etmv4_drvdata *drvdata)
 {
 	u64 trfcr, guest_trfcr;
+	struct etmv4_config *config = &drvdata->active_config;
 
 	/* If the CPU doesn't support FEAT_TRF, nothing to do */
 	if (!drvdata->trfcr)
 		return;
 
-	if (drvdata->config.mode & ETM_MODE_EXCL_HOST)
+	if (config->mode & ETM_MODE_EXCL_HOST)
 		trfcr = drvdata->trfcr & ~(TRFCR_EL1_ExTRE | TRFCR_EL1_E0TRE);
 	else
 		trfcr = etm4x_get_kern_user_filter(drvdata);
@@ -305,7 +310,7 @@ static void etm4x_allow_trace(struct etmv4_drvdata *drvdata)
 	write_trfcr(trfcr);
 
 	/* Set filters for guests and pass to KVM */
-	if (drvdata->config.mode & ETM_MODE_EXCL_GUEST)
+	if (config->mode & ETM_MODE_EXCL_GUEST)
 		guest_trfcr = drvdata->trfcr & ~(TRFCR_EL1_ExTRE | TRFCR_EL1_E0TRE);
 	else
 		guest_trfcr = etm4x_get_kern_user_filter(drvdata);
@@ -499,7 +504,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 {
 	int i, rc;
 	const struct etmv4_caps *caps = &drvdata->caps;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 	struct coresight_device *csdev = drvdata->csdev;
 	struct device *etm_dev = &csdev->dev;
 	struct csdev_access *csa = &csdev->access;
@@ -616,19 +621,36 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 static void etm4_enable_sysfs_smp_call(void *info)
 {
 	struct etm4_enable_arg *arg = info;
+	struct etmv4_drvdata *drvdata;
 	struct coresight_device *csdev;
 
 	if (WARN_ON(!arg))
 		return;
 
-	csdev = arg->drvdata->csdev;
+	drvdata = arg->drvdata;
+	csdev = drvdata->csdev;
 	if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) {
 		/* Someone is already using the tracer */
 		arg->rc = -EBUSY;
 		return;
 	}
 
-	arg->rc = etm4_enable_hw(arg->drvdata);
+	drvdata->active_config = drvdata->config;
+
+	if (arg->cfg_hash) {
+		arg->rc = cscfg_csdev_enable_active_config(csdev,
+							   arg->cfg_hash,
+							   arg->preset);
+		if (arg->rc)
+			return;
+	}
+
+	drvdata->trcid = arg->trace_id;
+
+	/* Tracer will never be paused in sysfs mode */
+	drvdata->paused = false;
+
+	arg->rc = etm4_enable_hw(drvdata);
 
 	/* The tracer didn't start */
 	if (arg->rc)
@@ -670,7 +692,7 @@ static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata,
 	int ctridx;
 	int rselector;
 	const struct etmv4_caps *caps = &drvdata->caps;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 
 	/* No point in trying if we don't have at least one counter */
 	if (!caps->nr_cntr)
@@ -754,7 +776,7 @@ static int etm4_parse_event_config(struct coresight_device *csdev,
 	int ret = 0;
 	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	const struct etmv4_caps *caps = &drvdata->caps;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 	struct perf_event_attr max_timestamp = {
 		.ATTR_CFG_FLD_timestamp_CFG = U64_MAX,
 	};
@@ -916,24 +938,18 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
 
 	/* enable any config activated by configfs */
 	cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset);
-	if (cfg_hash) {
-		ret = cscfg_csdev_enable_active_config(csdev, cfg_hash, preset);
-		if (ret)
-			return ret;
-	}
 
 	raw_spin_lock(&drvdata->spinlock);
 
-	drvdata->trcid = path->trace_id;
-
-	/* Tracer will never be paused in sysfs mode */
-	drvdata->paused = false;
-
 	/*
 	 * Executing etm4_enable_hw on the cpu whose ETM is being enabled
 	 * ensures that register writes occur when cpu is powered.
 	 */
 	arg.drvdata = drvdata;
+	arg.cfg_hash = cfg_hash;
+	arg.preset = preset;
+	arg.trace_id = path->trace_id;
+
 	ret = smp_call_function_single(drvdata->cpu,
 				       etm4_enable_sysfs_smp_call, &arg, 1);
 	if (!ret)
@@ -1034,7 +1050,7 @@ static void etm4_disable_hw(struct etmv4_drvdata *drvdata)
 {
 	u32 control;
 	const struct etmv4_caps *caps = &drvdata->caps;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 	struct coresight_device *csdev = drvdata->csdev;
 	struct csdev_access *csa = &csdev->access;
 	int i;
@@ -1070,6 +1086,8 @@ static void etm4_disable_sysfs_smp_call(void *info)
 
 	etm4_disable_hw(drvdata);
 
+	cscfg_csdev_disable_active_config(drvdata->csdev);
+
 	coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED);
 }
 
@@ -1130,9 +1148,6 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
 				 drvdata, 1);
 
 	raw_spin_unlock(&drvdata->spinlock);
-
-	cscfg_csdev_disable_active_config(csdev);
-
 	cpus_read_unlock();
 
 	/*
@@ -1375,6 +1390,7 @@ static void etm4_init_arch_data(void *info)
 	struct etm4_init_arg *init_arg = info;
 	struct etmv4_drvdata *drvdata;
 	struct etmv4_caps *caps;
+	struct etmv4_config *config;
 	struct csdev_access *csa;
 	struct device *dev = init_arg->dev;
 	int i;
@@ -1382,6 +1398,7 @@ static void etm4_init_arch_data(void *info)
 	drvdata = dev_get_drvdata(init_arg->dev);
 	caps = &drvdata->caps;
 	csa = init_arg->csa;
+	config = &drvdata->active_config;
 
 	/*
 	 * If we are unable to detect the access mechanism,
@@ -1442,7 +1459,7 @@ static void etm4_init_arch_data(void *info)
 
 	/* EXLEVEL_S, bits[19:16] Secure state instruction tracing */
 	caps->s_ex_level = FIELD_GET(TRCIDR3_EXLEVEL_S_MASK, etmidr3);
-	drvdata->config.s_ex_level = caps->s_ex_level;
+	config->s_ex_level = caps->s_ex_level;
 	/* EXLEVEL_NS, bits[23:20] Non-secure state instruction tracing */
 	caps->ns_ex_level = FIELD_GET(TRCIDR3_EXLEVEL_NS_MASK, etmidr3);
 	/*
@@ -1687,7 +1704,7 @@ static void etm4_set_default(struct etmv4_config *config)
 static int etm4_get_next_comparator(struct etmv4_drvdata *drvdata, u32 type)
 {
 	int nr_comparator, index = 0;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 
 	/*
 	 * nr_addr_cmp holds the number of comparator _pair_, so time 2
@@ -1728,7 +1745,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
 {
 	int i, comparator, ret = 0;
 	u64 address;
-	struct etmv4_config *config = &drvdata->config;
+	struct etmv4_config *config = &drvdata->active_config;
 	struct etm_filters *filters = event->hw.addr_filters;
 
 	if (!filters)
@@ -2250,7 +2267,8 @@ static int etm4_add_coresight_dev(struct etm4_init_arg *init_arg)
 	if (!desc.name)
 		return -ENOMEM;
 
-	etm4_set_default(&drvdata->config);
+	etm4_set_default(&drvdata->active_config);
+	drvdata->config = drvdata->active_config;
 
 	pdata = coresight_get_platform_data(dev);
 	if (IS_ERR(pdata))
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 57508d301327..33a4f68dd0cb 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -1069,6 +1069,7 @@ struct etmv4_save_state {
  *		allows tracing at all ELs. We don't want to compute this
  *		at runtime, due to the additional setting of TRFCR_CX when
  *		in EL2. Otherwise, 0.
+ * @active_config:	structure holding current applied configuration parameters.
  * @config:	structure holding configuration parameters.
  * @save_state:	State to be preserved across power loss
  * @paused:	Indicates if the trace unit is paused.
@@ -1089,6 +1090,7 @@ struct etmv4_drvdata {
 	bool				os_unlock : 1;
 	bool				paused : 1;
 	u64				trfcr;
+	struct etmv4_config		active_config;
 	struct etmv4_config		config;
 	struct etmv4_save_state		*save_state;
 	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}