coresight: etm4x: moving etm_drvdata::enable to atomic field

Similarly to ETMv3, moving etmv4_drvdata::enable to an atomic
type that gives the 'mode' of a tracer and prevents multiple,
simultanious access by different subsystems.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 92524fe1aa6c45122e7bf9380e70993d200ade32..9f51a8f47650eeab569fa98838a95c1c7310893f 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -34,6 +34,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/perf_event.h>
 #include <asm/sections.h>
+#include <asm/local.h>
 
 #include "coresight-etm4x.h"
 
@@ -76,7 +77,7 @@ static int etm4_trace_id(struct coresight_device *csdev)
        unsigned long flags;
        int trace_id = -1;
 
-       if (!drvdata->enable)
+       if (!local_read(&drvdata->mode))
                return drvdata->trcid;
 
        spin_lock_irqsave(&drvdata->spinlock, flags);
@@ -188,8 +189,7 @@ static void etm4_enable_hw(void *info)
        dev_dbg(drvdata->dev, "cpu: %d enable smp call done\n", drvdata->cpu);
 }
 
-static int etm4_enable(struct coresight_device *csdev,
-                      struct perf_event_attr *attr, u32 mode)
+static int etm4_enable_sysfs(struct coresight_device *csdev)
 {
        struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        int ret;
@@ -204,18 +204,46 @@ static int etm4_enable(struct coresight_device *csdev,
                                       etm4_enable_hw, drvdata, 1);
        if (ret)
                goto err;
-       drvdata->enable = true;
-       drvdata->sticky_enable = true;
 
+       drvdata->sticky_enable = true;
        spin_unlock(&drvdata->spinlock);
 
        dev_info(drvdata->dev, "ETM tracing enabled\n");
        return 0;
+
 err:
        spin_unlock(&drvdata->spinlock);
        return ret;
 }
 
+static int etm4_enable(struct coresight_device *csdev,
+                      struct perf_event_attr *attr, u32 mode)
+{
+       int ret;
+       u32 val;
+       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+       val = local_cmpxchg(&drvdata->mode, CS_MODE_DISABLED, mode);
+
+       /* Someone is already using the tracer */
+       if (val)
+               return -EBUSY;
+
+       switch (mode) {
+       case CS_MODE_SYSFS:
+               ret = etm4_enable_sysfs(csdev);
+               break;
+       default:
+               ret = -EINVAL;
+       }
+
+       /* The tracer didn't start */
+       if (ret)
+               local_set(&drvdata->mode, CS_MODE_DISABLED);
+
+       return ret;
+}
+
 static void etm4_disable_hw(void *info)
 {
        u32 control;
@@ -238,7 +266,7 @@ static void etm4_disable_hw(void *info)
        dev_dbg(drvdata->dev, "cpu: %d disable smp call done\n", drvdata->cpu);
 }
 
-static void etm4_disable(struct coresight_device *csdev)
+static void etm4_disable_sysfs(struct coresight_device *csdev)
 {
        struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -256,7 +284,6 @@ static void etm4_disable(struct coresight_device *csdev)
         * ensures that register writes occur when cpu is powered.
         */
        smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1);
-       drvdata->enable = false;
 
        spin_unlock(&drvdata->spinlock);
        put_online_cpus();
@@ -264,6 +291,30 @@ static void etm4_disable(struct coresight_device *csdev)
        dev_info(drvdata->dev, "ETM tracing disabled\n");
 }
 
+static void etm4_disable(struct coresight_device *csdev)
+{
+       u32 mode;
+       struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+       /*
+        * For as long as the tracer isn't disabled another entity can't
+        * change its status.  As such we can read the status here without
+        * fearing it will change under us.
+        */
+       mode = local_read(&drvdata->mode);
+
+       switch (mode) {
+       case CS_MODE_DISABLED:
+               break;
+       case CS_MODE_SYSFS:
+               etm4_disable_sysfs(csdev);
+               break;
+       }
+
+       if (mode)
+               local_set(&drvdata->mode, CS_MODE_DISABLED);
+}
+
 static const struct coresight_ops_source etm4_source_ops = {
        .cpu_id         = etm4_cpu_id,
        .trace_id       = etm4_trace_id,
@@ -531,7 +582,7 @@ static int etm4_cpu_callback(struct notifier_block *nfb, unsigned long action,
                        etmdrvdata[cpu]->os_unlock = true;
                }
 
-               if (etmdrvdata[cpu]->enable)
+               if (local_read(&etmdrvdata[cpu]->mode))
                        etm4_enable_hw(etmdrvdata[cpu]);
                spin_unlock(&etmdrvdata[cpu]->spinlock);
                break;
@@ -544,7 +595,7 @@ static int etm4_cpu_callback(struct notifier_block *nfb, unsigned long action,
 
        case CPU_DYING:
                spin_lock(&etmdrvdata[cpu]->spinlock);
-               if (etmdrvdata[cpu]->enable)
+               if (local_read(&etmdrvdata[cpu]->mode))
                        etm4_disable_hw(etmdrvdata[cpu]);
                spin_unlock(&etmdrvdata[cpu]->spinlock);
                break;

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 6ff499bfb2f2b8f677d307d9df871cf20dcbb142..f7748ae634510932124faded9e22975c3faa9b3d 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -13,6 +13,7 @@
 #ifndef _CORESIGHT_CORESIGHT_ETM_H
 #define _CORESIGHT_CORESIGHT_ETM_H
 
+#include <asm/local.h>
 #include <linux/spinlock.h>
 #include "coresight-priv.h"
 
@@ -290,6 +291,7 @@ struct etmv4_config {
  * @dev:        The device entity associated to this component.
  * @csdev:      Component vitals needed by the framework.
  * @spinlock:   Only one at a time pls.
+ * @mode:      This tracer's mode, i.e sysFS, Perf or disabled.
  * @cpu:        The cpu this component is affined to.
  * @arch:       ETM version number.
  * @nr_pe:     The number of processing entity available for tracing.
@@ -316,7 +318,6 @@ struct etmv4_config {
  *             supported for the corresponding Exception level.
  * @ns_ex_level:In non-secure state, indicates whether instruction tracing is
  *             supported for the corresponding Exception level.
- * @enable:    Is this ETM currently tracing.
  * @sticky_enable: true if ETM base configuration has been done.
  * @boot_enable:True if we should start tracing at boot time.
  * @os_unlock:  True if access to management registers is allowed.
@@ -346,6 +347,7 @@ struct etmv4_drvdata {
        struct device                   *dev;
        struct coresight_device         *csdev;
        spinlock_t                      spinlock;
+       local_t                         mode;
        int                             cpu;
        u8                              arch;
        u8                              nr_pe;
@@ -368,7 +370,6 @@ struct etmv4_drvdata {
        u8                              ccitmin;
        u8                              s_ex_level;
        u8                              ns_ex_level;
-       bool                            enable;
        bool                            sticky_enable;
        bool                            boot_enable;
        bool                            os_unlock;