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>

2 files changed, 85 insertions, 0 deletions

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index d9efbbfa2bdf..c44a7dce9086 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -18,5 +18,6 @@ obj-$(CONFIG_FTRACE) += trace_functions.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
+obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
new file mode 100644
index 000000000000..e4dd03cc5aa6
--- /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);
+}