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Subject[PATCH] ftrace: Add debug_dump trace to dump binary data from kernel to userspace
Date
The trace add a new interface debug_dump() which can be used
to dump binary data using ftrace framework. Use the dump mode
of iterator by 'echo dump > iter_ctrl' to read the value in
userspace

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

---
include/linux/debug_dump.h | 10 ++++
kernel/trace/Kconfig | 6 ++
kernel/trace/Makefile | 1 +
kernel/trace/trace_debugdump.c | 103 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 120 insertions(+), 0 deletions(-)

diff --git a/include/linux/debug_dump.h b/include/linux/debug_dump.h
new file mode 100644
index 0000000..2c1836d
--- /dev/null
+++ b/include/linux/debug_dump.h
@@ -0,0 +1,10 @@
+#ifndef _LINUX_DEBUGDUMP_H
+#define _LINUX_DEBUGDUMP_H
+#include <linux/marker.h>
+
+#ifdef CONFIG_DEBUG_DUMP
+extern int debug_dump(void *p, int len);
+#else
+#define debug_dump(p, len)
+#endif
+#endif /* _LINUX_DEBUGDUMP_H */
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 30eccc8..247cf3f 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -261,4 +261,10 @@ config DEBUG_PRINT
help
This tracer can be used for printk style debugging.

+config DEBUG_DUMP
+ bool "Trace based dump support"
+ depends on DEBUG_KERNEL
+ select TRACING
+ help
+ This tracer can be used to dump binary data from kernel
endmenu
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 86e5869..b1c6dec 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -32,5 +32,6 @@ obj-$(CONFIG_BOOT_TRACER) += trace_boot.o
obj-$(CONFIG_FUNCTION_RET_TRACER) += trace_functions_return.o
obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
obj-$(CONFIG_DEBUG_PRINT) += trace_debugprint.o
+obj-$(CONFIG_DEBUG_DUMP) += trace_debugdump.o

libftrace-y := ftrace.o
diff --git a/kernel/trace/trace_debugdump.c b/kernel/trace/trace_debugdump.c
new file mode 100644
index 0000000..3ebae2a
--- /dev/null
+++ b/kernel/trace/trace_debugdump.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright IBM Corporation, 2008
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/ftrace.h>
+
+#include "trace.h"
+
+static struct trace_array *ctx_trace;
+static int __read_mostly dd_tracer_enabled;
+
+int debug_dump(void *bin_data, int len)
+{
+ int size;
+ unsigned long irq_flags;
+ struct dump_entry *entry;
+ struct ring_buffer_event *event;
+
+ if (!dd_tracer_enabled)
+ return 0;
+
+ size = sizeof(*entry) + len;
+ event = ring_buffer_lock_reserve(ctx_trace->buffer, size, &irq_flags);
+ if (!event)
+ return 0;
+ entry = ring_buffer_event_data(event);
+ tracing_generic_entry_update(&entry->ent, 0, preempt_count());
+ entry->ent.type = TRACE_BIN_DUMP;
+ entry->len = len;
+
+ memcpy(&entry->buf, bin_data, len);
+ ring_buffer_unlock_commit(ctx_trace->buffer, event, irq_flags);
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(debug_dump);
+
+static void dd_reset(struct trace_array *tr)
+{
+ int cpu;
+
+ tr->time_start = ftrace_now(tr->cpu);
+
+ for_each_online_cpu(cpu)
+ tracing_reset(tr, cpu);
+}
+
+static void dd_trace_start(struct trace_array *tr)
+{
+ dd_reset(tr);
+ dd_tracer_enabled = 1;
+}
+
+static void dd_trace_stop(struct trace_array *tr)
+{
+ dd_tracer_enabled = 0;
+ /* Nothing to do! */
+}
+
+static void dd_trace_init(struct trace_array *tr)
+{
+ ctx_trace = tr;
+ /*
+ * enable the trace during init if
+ * we have enabled flag already set
+ */
+ if (tracing_is_enabled())
+ dd_trace_start(tr);
+}
+
+static void dd_trace_reset(struct trace_array *tr)
+{
+ if (dd_tracer_enabled)
+ dd_trace_stop(tr);
+}
+
+struct tracer dd_trace __read_mostly =
+{
+ .name = "debug_dump",
+ .init = dd_trace_init,
+ .reset = dd_trace_reset,
+ .start = dd_trace_start,
+ .stop = dd_trace_stop,
+};
+
+__init static int init_dd_trace(void)
+{
+ return register_tracer(&dd_trace);
+}
+device_initcall(init_dd_trace);
--
tg: (140170e..) an/ftrace-debug-dump.patch (depends on: an/ftrace-bin-dump.patch)

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