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SubjectRe: [PATCH 4/8] ARM: etm: Allow range selection
On Mon, Feb 14, 2011 at 10:11:12PM -0800, Arve Hjønnevåg wrote:
> 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.

Since you're adding this, I think it might make sense to add a 3rd optional
ctx id field, so that userspace tracing is also possible, especially when
on-chip ETB sizes increase to something more sensible than what they are
these days.

Thanks!

>
> Signed-off-by: Arve Hjønnevåg <arve@android.com>
> ---
> arch/arm/kernel/etm.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
> 1 files changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
> index bc7d8f2..8a1c422 100644
> --- a/arch/arm/kernel/etm.c
> +++ b/arch/arm/kernel/etm.c
> @@ -40,12 +40,17 @@ 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)
> {
> @@ -115,8 +120,12 @@ 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);
> @@ -525,6 +534,35 @@ 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 __init etm_probe(struct amba_device *dev, struct amba_id *id)
> {
> struct tracectx *t = &tracer;
> @@ -576,6 +614,10 @@ static int __init etm_probe(struct amba_device *dev, 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:
> @@ -605,6 +647,7 @@ 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;
> }
> --
> 1.7.3.1
>
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