[PATCH 04/15] ARM: etm: Allow range selection

John Stultz
2012-06-20T22:51:07Z

From: Arve Hjønnevåg <arve@android.com>

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.

CC: Russell King <linux@arm.linux.org.uk>
CC: Paul Gortmaker <paul.gortmaker@windriver.com>
CC: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
arch/arm/kernel/etm.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 46 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index a51bccc..bf34d34 100644
--- 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 __devinit etm_probe(struct amba_device *dev, const struct amba_id *id)
{
struct tracectx *t = &tracer;
@@ -577,6 +615,10 @@ static int __devinit 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;
}
--
1.7.9.5