[PATCH v12 05/14] coresight: etm3x: fix inconsistencies with sysfs configuration

The current ETM3x 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.

To resolve these issues, separate the configuration into:

- curr_config: the configuration applied to the current session - config: the configuration set via sysfs

Additionally:

- Since curr_config and related fields are accessed only by the local CPU in etm_enable/disable_sysfs_smp_call() (similar to perf enable/disable), remove the lock/unlock from the sysfs enable/disable path and starting/dying_cpu path except when to access config fields only.

- Some of sysfs interface read etm register directly. To reduce lock scope while the etm_enable_hw()/etm_disable_hw(), handle it via IPI so that registers could be read from on proper CPU.

Fixes: 1925a470ce69 ("coresight: etm3x: splitting struct etm_drvdata") Tested-by: Leo Yan leo.yan@arm.com Signed-off-by: Yeoreum Yun yeoreum.yun@arm.com --- drivers/hwtracing/coresight/coresight-etm.h | 4 +- drivers/hwtracing/coresight/coresight-etm3x-core.c | 66 ++++++++++-------- .../hwtracing/coresight/coresight-etm3x-sysfs.c | 80 +++++++++++++++------- 3 files changed, 98 insertions(+), 52 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h index 1d753cca2943..52f23a3c7364 100644 --- a/drivers/hwtracing/coresight/coresight-etm.h +++ b/drivers/hwtracing/coresight/coresight-etm.h @@ -226,7 +226,8 @@ struct etm_config { * @etmccr: value of register ETMCCR. * @etmccer: value of register ETMCCER. * @traceid: value of the current ID for this component. - * @config: structure holding configuration parameters. + * @curr_config: structure holding current running configuration. + * @config: structure holding sysfs mode configuration. */ struct etm_drvdata { struct csdev_access csa; @@ -248,6 +249,7 @@ struct etm_drvdata { u32 etmccr; u32 etmccer; u32 traceid; + struct etm_config curr_config; struct etm_config config; };

diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c index 862ad0786699..dcadcc383012 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c @@ -308,7 +308,7 @@ void etm_config_trace_mode(struct etm_config *config) static int etm_parse_event_config(struct etm_drvdata *drvdata, struct perf_event *event) { - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->curr_config; struct perf_event_attr *attr = &event->attr; u8 ts_level;

@@ -367,7 +367,7 @@ static int etm_enable_hw(struct etm_drvdata *drvdata) { int i, rc; u32 etmcr; - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->curr_config; struct coresight_device *csdev = drvdata->csdev;

CS_UNLOCK(drvdata->csa.base); @@ -448,26 +448,22 @@ struct etm_enable_arg { static void etm_enable_sysfs_smp_call(void *info) { struct etm_enable_arg *arg = info; + struct etm_drvdata *drvdata; struct coresight_device *csdev;

if (WARN_ON(!arg)) return;

- csdev = arg->drvdata->csdev; - if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) { - /* Someone is already using the tracer */ - arg->rc = -EBUSY; - return; - } + drvdata = arg->drvdata; + csdev = drvdata->csdev;

- arg->rc = etm_enable_hw(arg->drvdata); + drvdata->traceid = arg->path->trace_id;

- /* The tracer didn't start */ - if (arg->rc) { - coresight_set_mode(csdev, CS_MODE_DISABLED); + arg->rc = etm_enable_hw(arg->drvdata); + if (arg->rc) return; - }

+ drvdata->sticky_enable = true; csdev->path = arg->path; }

@@ -512,9 +508,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev, struct coresight_pat struct etm_enable_arg arg = { }; int ret;

- spin_lock(&drvdata->spinlock); - - drvdata->traceid = path->trace_id; + if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) { + /* Someone is already using the tracer */ + return -EBUSY; + }

/* * Configure the ETM only if the CPU is online. If it isn't online @@ -523,23 +520,27 @@ static int etm_enable_sysfs(struct coresight_device *csdev, struct coresight_pat if (cpu_online(drvdata->cpu)) { arg.drvdata = drvdata; arg.path = path; + + scoped_guard(spinlock, &drvdata->spinlock) { + drvdata->curr_config = drvdata->config; + } + ret = smp_call_function_single(drvdata->cpu, etm_enable_sysfs_smp_call, &arg, 1); if (!ret) ret = arg.rc; - if (!ret) - drvdata->sticky_enable = true; } else { ret = -ENODEV; }

- if (ret) + if (!ret) { + dev_dbg(&csdev->dev, "ETM tracing enabled\n"); + } else { etm_release_trace_id(drvdata); + /* The tracer didn't start */ + coresight_set_mode(csdev, CS_MODE_DISABLED); + }

- spin_unlock(&drvdata->spinlock); - - if (!ret) - dev_dbg(&csdev->dev, "ETM tracing enabled\n"); return ret; }

@@ -565,7 +566,7 @@ static int etm_enable(struct coresight_device *csdev, struct perf_event *event, static void etm_disable_hw(struct etm_drvdata *drvdata) { int i; - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->curr_config; struct coresight_device *csdev = drvdata->csdev;

CS_UNLOCK(drvdata->csa.base); @@ -593,7 +594,6 @@ static void etm_disable_sysfs_smp_call(void *info) etm_disable_hw(drvdata);

drvdata->csdev->path = NULL; - coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED); }

static void etm_disable_perf(struct coresight_device *csdev) @@ -630,8 +630,9 @@ static void etm_disable_perf(struct coresight_device *csdev) static void etm_disable_sysfs(struct coresight_device *csdev) { struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); - - spin_lock(&drvdata->spinlock); + struct etm_config *config = &drvdata->config; + const struct etm_config *curr_config = &drvdata->curr_config; + int i;

/* * Executing etm_disable_hw on the cpu whose ETM is being disabled @@ -640,7 +641,14 @@ static void etm_disable_sysfs(struct coresight_device *csdev) smp_call_function_single(drvdata->cpu, etm_disable_sysfs_smp_call, drvdata, 1);

- spin_unlock(&drvdata->spinlock); + /* + * Userspace may read seq_curr_state and cntr_val through sysfs + * after the sysfs-session has been disabled. + */ + for (i = 0; i < drvdata->nr_cntr; i++) + config->cntr_val[i] = curr_config->cntr_val[i]; + + config->seq_curr_state = curr_config->seq_curr_state;

/* * we only release trace IDs when resetting sysfs. @@ -649,6 +657,8 @@ static void etm_disable_sysfs(struct coresight_device *csdev) * prior trace id allocation method */

+ coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED); + dev_dbg(&csdev->dev, "ETM tracing disabled\n"); }

diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c index cdb70a4382eb..284998f18017 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c @@ -6,10 +6,48 @@

#include <linux/pid_namespace.h> #include <linux/pm_runtime.h> +#include <linux/smp.h> #include <linux/sysfs.h> #include "coresight-etm.h" #include "coresight-priv.h"

+struct etm_readl_cslocked_arg { + struct etm_drvdata *drvdata; + u32 off; + unsigned long *val; +}; + +static void etm_readl_cslocked_smp_call(void *info) +{ + struct etm_readl_cslocked_arg *arg = info; + + CS_UNLOCK(arg->drvdata->csa.base); + *arg->val = etm_readl(arg->drvdata, arg->off); + CS_LOCK(arg->drvdata->csa.base); +} + +static int etm_readl_cslocked(struct etm_drvdata *drvdata, u32 off, + unsigned long *val) +{ + int ret; + struct etm_readl_cslocked_arg arg; + + ret = pm_runtime_get_sync(drvdata->csdev->dev.parent); + if (ret < 0) + goto out; + + arg.drvdata = drvdata; + arg.off = off; + arg.val = val; + + ret = smp_call_function_single(drvdata->cpu, + etm_readl_cslocked_smp_call, + (void *)&arg, 1); +out: + pm_runtime_put(drvdata->csdev->dev.parent); + return ret; +} + static ssize_t nr_addr_cmp_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -45,18 +83,13 @@ static DEVICE_ATTR_RO(nr_ctxid_cmp); static ssize_t etmsr_show(struct device *dev, struct device_attribute *attr, char *buf) { - unsigned long flags, val; + int ret; + unsigned long val; struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);

- pm_runtime_get_sync(dev->parent); - spin_lock_irqsave(&drvdata->spinlock, flags); - CS_UNLOCK(drvdata->csa.base); - - val = etm_readl(drvdata, ETMSR); - - CS_LOCK(drvdata->csa.base); - spin_unlock_irqrestore(&drvdata->spinlock, flags); - pm_runtime_put(dev->parent); + ret = etm_readl_cslocked(drvdata, ETMSR, &val); + if (ret) + return ret;

return sprintf(buf, "%#lx\n", val); } @@ -76,7 +109,7 @@ static ssize_t reset_store(struct device *dev, return ret;

if (IS_ERR_OR_NULL(drvdata->csdev) || - coresight_get_mode(drvdata->csdev)) + coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) return -EBUSY;

if (val) { @@ -721,7 +754,9 @@ static DEVICE_ATTR_RW(cntr_rld_event); static ssize_t cntr_val_show(struct device *dev, struct device_attribute *attr, char *buf) { + int ret; u32 val; + unsigned long val2; struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent); struct etm_config *config = &drvdata->config;

@@ -730,7 +765,10 @@ static ssize_t cntr_val_show(struct device *dev, val = config->cntr_val[config->cntr_idx]; spin_unlock(&drvdata->spinlock); } else { - val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx)); + ret = etm_readl_cslocked(drvdata, ETMCNTVRn(config->cntr_idx), &val2); + if (ret) + return ret; + val = val2; }

return sysfs_emit(buf, "%#x\n", val); @@ -749,7 +787,7 @@ static ssize_t cntr_val_store(struct device *dev, if (ret) return ret; if (IS_ERR_OR_NULL(drvdata->csdev) || - coresight_get_mode(drvdata->csdev)) + coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) return -EBUSY;

spin_lock(&drvdata->spinlock); @@ -937,7 +975,8 @@ static DEVICE_ATTR_RW(seq_13_event); static ssize_t seq_curr_state_show(struct device *dev, struct device_attribute *attr, char *buf) { - unsigned long val, flags; + int ret; + unsigned long val; struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent); struct etm_config *config = &drvdata->config;

@@ -946,15 +985,10 @@ static ssize_t seq_curr_state_show(struct device *dev, goto out; }

- pm_runtime_get_sync(dev->parent); - spin_lock_irqsave(&drvdata->spinlock, flags); - - CS_UNLOCK(drvdata->csa.base); - val = (etm_readl(drvdata, ETMSQR) & ETM_SQR_MASK); - CS_LOCK(drvdata->csa.base); - - spin_unlock_irqrestore(&drvdata->spinlock, flags); - pm_runtime_put(dev->parent); + ret = etm_readl_cslocked(drvdata, ETMSQR, &val); + if (ret) + return ret; + val &= ETM_SQR_MASK; out: return sprintf(buf, "%#lx\n", val); }