[PATCH v7 08/13] coresight: etm4x: fix inconsistencies with sysfs configuration
Leo Yan
leo.yan at arm.com
Thu May 28 07:09:43 PDT 2026
On Tue, May 19, 2026 at 04:48:07PM +0100, Yeoreum Yun wrote:
[...]
> --- 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;
Wouldn't it make more sense to keep using drvdata->config for cfgfs?
This would avoid cfgfs updating the active configuration while a session
is enabled.
My understanding is after refactoring cfgfs, we will never expose
active_config or config anymore so this should not an issue. Before
that, maybe we just keep to use config so can avoid mess.
> 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 9b477b36b432..f0a9f2ef4b27 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -243,6 +243,7 @@ void etm4_release_trace_id(struct etmv4_drvdata *drvdata)
> struct etm4_enable_arg {
> struct etmv4_drvdata *drvdata;
> struct coresight_path *path;
> + struct etmv4_config config;
> int rc;
> };
>
> @@ -268,10 +269,11 @@ 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;
> @@ -279,7 +281,7 @@ 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
> @@ -290,12 +292,13 @@ 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);
> @@ -303,7 +306,7 @@ 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);
> @@ -497,7 +500,7 @@ 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;
> @@ -618,27 +621,53 @@ 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;
> + unsigned long cfg_hash;
> + int preset;
>
> 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);
> + /* enable any config activated by configfs */
> + cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset);
>
> - /* The tracer didn't start */
> + drvdata->active_config = arg->config;
Can move this down to just before drvdata->trcid assignment so cscfg
operations can be put together?
> +
> + if (cfg_hash) {
> + arg->rc = cscfg_csdev_enable_active_config(csdev,
> + cfg_hash,
> + preset);
> + if (arg->rc)
> + goto err;
> + }
> +
> + drvdata->trcid = arg->path->trace_id;
> +
> + /* Tracer will never be paused in sysfs mode */
> + drvdata->paused = false;
> +
> + arg->rc = etm4_enable_hw(drvdata);
> if (arg->rc) {
> - coresight_set_mode(csdev, CS_MODE_DISABLED);
> - return;
> + cscfg_csdev_disable_active_config(csdev);
> + goto err;
Add a new goto tag (like err_enable_hw) for the disable_active_config
rollback?
> }
>
> + drvdata->sticky_enable = true;
> csdev->path = arg->path;
> +
> + return;
> +err:
> + /* The tracer didn't start */
> + coresight_set_mode(csdev, CS_MODE_DISABLED);
> }
>
> /*
> @@ -676,7 +705,7 @@ 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)
> @@ -760,7 +789,7 @@ 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,
> };
> @@ -922,25 +951,7 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
> {
> struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> struct etm4_enable_arg arg = { };
> - unsigned long cfg_hash;
> - int ret, preset;
> -
> - /* 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) {
> - etm4_release_trace_id(drvdata);
> - return ret;
> - }
> - }
> -
> - raw_spin_lock(&drvdata->spinlock);
> -
> - drvdata->trcid = path->trace_id;
> -
> - /* Tracer will never be paused in sysfs mode */
> - drvdata->paused = false;
> + int ret;
>
> /*
> * Executing etm4_enable_hw on the cpu whose ETM is being enabled
> @@ -948,20 +959,20 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
> */
> arg.drvdata = drvdata;
> arg.path = path;
> +
> + raw_spin_lock(&drvdata->spinlock);
> + arg.config = drvdata->config;
> + raw_spin_unlock(&drvdata->spinlock);
> +
> ret = smp_call_function_single(drvdata->cpu,
> etm4_enable_sysfs_smp_call, &arg, 1);
> if (!ret)
> ret = arg.rc;
> if (!ret)
> - drvdata->sticky_enable = true;
> -
> - if (ret)
> + dev_dbg(&csdev->dev, "ETM tracing enabled\n");
> + else
> etm4_release_trace_id(drvdata);
>
> - raw_spin_unlock(&drvdata->spinlock);
> -
> - if (!ret)
> - dev_dbg(&csdev->dev, "ETM tracing enabled\n");
> return ret;
> }
>
> @@ -1048,7 +1059,7 @@ 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;
> @@ -1091,6 +1102,8 @@ static void etm4_disable_sysfs_smp_call(void *info)
> etm4_disable_hw(drvdata);
>
> drvdata->csdev->path = NULL;
> + cscfg_csdev_disable_active_config(drvdata->csdev);
Move cscfg_csdev_disable_active_config() just after etm4_disable_hw() so
the sequence is consistent with perf mode.
[...]
> @@ -1449,7 +1458,7 @@ 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;
config->s_ex_level is redundant and not really a configuration item.
We should use caps->s_ex_level instead of config->s_ex_level wherever
it is used.
Thanks,
Leo
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