ARM: etm: Allow range selection

Trace kernel text segment by default as before, allow tracing of other
ranges by writing a range to /sys/devices/etm/trace_range, or to trace
everything by writing 0 0.

Change-Id: Ibb734ca820fedf79560b20536247f1e1700cdc71
Signed-off-by: Arve Hjønnevåg <arve@android.com>

diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index 3cd8a28ab8423df922f330f8247cd04608366ec5..28d7b609b6d80536853318f1b6e78efc8cddd21a 100644 (file)
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -41,12 +41,17 @@ struct tracectx {
        unsigned long   flags;
        int             ncmppairs;
        int             etm_portsz;
+       unsigned long   range_start;
+       unsigned long   range_end;
        struct device   *dev;
        struct clk      *emu_clk;
        struct mutex    mutex;
 };
 
-static struct tracectx tracer;
+static struct tracectx tracer = {
+       .range_start = (unsigned long)_stext,
+       .range_end = (unsigned long)_etext,
+};
 
 static inline bool trace_isrunning(struct tracectx *t)
 {
@@ -116,8 +121,12 @@ static int trace_start(struct tracectx *t)
                return -EFAULT;
        }
 
-       etm_setup_address_range(t, 1, (unsigned long)_stext,
-                       (unsigned long)_etext, 0, 0);
+       if (t->range_start || t->range_end)
+               etm_setup_address_range(t, 1,
+                                       t->range_start, t->range_end, 0, 0);
+       else
+               etm_writel(t, ETMTE_INCLEXCL, ETMR_TRACEENCTRL);
+
        etm_writel(t, 0, ETMR_TRACEENCTRL2);
        etm_writel(t, 0, ETMR_TRACESSCTRL);
        etm_writel(t, 0x6f, ETMR_TRACEENEVT);
@@ -526,6 +535,35 @@ static ssize_t trace_mode_store(struct kobject *kobj,
 static struct kobj_attribute trace_mode_attr =
        __ATTR(trace_mode, 0644, trace_mode_show, trace_mode_store);
 
+static ssize_t trace_range_show(struct kobject *kobj,
+                                 struct kobj_attribute *attr,
+                                 char *buf)
+{
+       return sprintf(buf, "%08lx %08lx\n",
+                       tracer.range_start, tracer.range_end);
+}
+
+static ssize_t trace_range_store(struct kobject *kobj,
+                                  struct kobj_attribute *attr,
+                                  const char *buf, size_t n)
+{
+       unsigned long range_start, range_end;
+
+       if (sscanf(buf, "%lx %lx", &range_start, &range_end) != 2)
+               return -EINVAL;
+
+       mutex_lock(&tracer.mutex);
+       tracer.range_start = range_start;
+       tracer.range_end = range_end;
+       mutex_unlock(&tracer.mutex);
+
+       return n;
+}
+
+
+static struct kobj_attribute trace_range_attr =
+       __ATTR(trace_range, 0644, trace_range_show, trace_range_store);
+
 static int etm_probe(struct amba_device *dev, const struct amba_id *id)
 {
        struct tracectx *t = &tracer;
@@ -577,6 +615,10 @@ static int etm_probe(struct amba_device *dev, const struct amba_id *id)
        if (ret)
                dev_dbg(&dev->dev, "Failed to create trace_mode in sysfs\n");
 
+       ret = sysfs_create_file(&dev->dev.kobj, &trace_range_attr.attr);
+       if (ret)
+               dev_dbg(&dev->dev, "Failed to create trace_range in sysfs\n");
+
        dev_dbg(t->dev, "ETM AMBA driver initialized.\n");
 
 out:
@@ -606,6 +648,7 @@ static int etm_remove(struct amba_device *dev)
        sysfs_remove_file(&dev->dev.kobj, &trace_running_attr.attr);
        sysfs_remove_file(&dev->dev.kobj, &trace_info_attr.attr);
        sysfs_remove_file(&dev->dev.kobj, &trace_mode_attr.attr);
+       sysfs_remove_file(&dev->dev.kobj, &trace_range_attr.attr);
 
        return 0;
 }