ftrace: add mmiotrace plugin

On Sat, 22 Mar 2008 13:07:47 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> > > i'd suggest the following: pull x86.git and sched-devel.git into a
> > > single tree [the two will combine without rejects]. Then try to add a
> > > kernel/tracing/trace_mmiotrace.c ftrace plugin. The trace_sysprof.c
> > > plugin might be a good example.
> >
> > I did this and now I have mmiotrace enabled/disabled via the tracing
> > framework (what do we call this, since ftrace is one of the tracers?).
>
> cool! could you send the patches for that? (even if they are not fully
> functional yet)

Patch attached in the end. Nice to see how much code disappeared. I tried
to mark all the features I had to break with XXX-comments.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 84 insertions, 0 deletions

diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
new file mode 100644
index 0000000..e4dd03c
--- /dev/null
+++ b/kernel/trace/trace_mmiotrace.c
@@ -0,0 +1,84 @@
+/*
+ * Memory mapped I/O tracing
+ *
+ * Copyright (C) 2008 Pekka Paalanen <pq@iki.fi>
+ */
+
+#define DEBUG 1
+
+#include <linux/kernel.h>
+#include <linux/mmiotrace.h>
+
+#include "trace.h"
+
+extern void
+__trace_special(void *__tr, void *__data,
+		unsigned long arg1, unsigned long arg2, unsigned long arg3);
+
+static struct trace_array *mmio_trace_array;
+
+
+static void mmio_trace_init(struct trace_array *tr)
+{
+	pr_debug("in %s\n", __func__);
+	mmio_trace_array = tr;
+	if (tr->ctrl)
+		enable_mmiotrace();
+}
+
+static void mmio_trace_reset(struct trace_array *tr)
+{
+	pr_debug("in %s\n", __func__);
+	if (tr->ctrl)
+		disable_mmiotrace();
+}
+
+static void mmio_trace_ctrl_update(struct trace_array *tr)
+{
+	pr_debug("in %s\n", __func__);
+	if (tr->ctrl)
+		enable_mmiotrace();
+	else
+		disable_mmiotrace();
+}
+
+static struct tracer mmio_tracer __read_mostly =
+{
+	.name		= "mmiotrace",
+	.init		= mmio_trace_init,
+	.reset		= mmio_trace_reset,
+	.ctrl_update	= mmio_trace_ctrl_update,
+};
+
+__init static int init_mmio_trace(void)
+{
+	int ret = init_mmiotrace();
+	if (ret)
+		return ret;
+	return register_tracer(&mmio_tracer);
+}
+device_initcall(init_mmio_trace);
+
+void mmio_trace_record(u32 type, unsigned long addr, unsigned long arg)
+{
+	struct trace_array *tr = mmio_trace_array;
+	struct trace_array_cpu *data = tr->data[smp_processor_id()];
+
+	if (!current || current->pid == 0) {
+		/*
+		 * XXX: This is a problem. We need to able to record, no
+		 * matter what. tracing_generic_entry_update() would crash.
+		 */
+		static unsigned limit;
+		if (limit++ < 12)
+			pr_err("Error in %s: no current.\n", __func__);
+		return;
+	}
+	if (!tr || !data) {
+		static unsigned limit;
+		if (limit++ < 12)
+			pr_err("%s: no tr or data\n", __func__);
+		return;
+	}
+	__trace_special(tr, data, type, addr, arg);
+}