lttng: debugfs and procfs ABI

Add the "lttng" virtual file to debugfs and procfs. All operations are
performed through ioctls (LTTng ioctl range is already reserved
upstream) on this virtual file and on anonymous file descriptors
returned by these ioctls. Each file descriptor is associated with a
tracer "object" (session, channel, stream, event, context).
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/ltt-debugfs-abi.h

+#ifndef _LTT_DEBUGFS_ABI_H
+#define _LTT_DEBUGFS_ABI_H
+
+/*
+ * ltt-debugfs-abi.h
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng debugfs ABI header
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/fs.h>
+
+#define LTTNG_SYM_NAME_LEN	128
+
+enum lttng_kernel_instrumentation {
+	LTTNG_KERNEL_TRACEPOINT	= 0,
+	LTTNG_KERNEL_KPROBE	= 1,
+	LTTNG_KERNEL_FUNCTION	= 2,
+	LTTNG_KERNEL_KRETPROBE	= 3,
+	LTTNG_KERNEL_NOOP	= 4,	/* not hooked */
+	LTTNG_KERNEL_SYSCALL	= 5,
+};
+
+/*
+ * LTTng consumer mode
+ */
+enum lttng_kernel_output {
+	LTTNG_KERNEL_SPLICE	= 0,
+	LTTNG_KERNEL_MMAP	= 1,
+};
+
+/*
+ * LTTng DebugFS ABI structures.
+ */
+
+struct lttng_kernel_channel {
+	int overwrite;				/* 1: overwrite, 0: discard */
+	uint64_t subbuf_size;			/* in bytes */
+	uint64_t num_subbuf;
+	unsigned int switch_timer_interval;	/* usecs */
+	unsigned int read_timer_interval;	/* usecs */
+	enum lttng_kernel_output output;	/* splice, mmap */
+};
+
+struct lttng_kernel_kretprobe {
+	uint64_t addr;
+
+	uint64_t offset;
+	char symbol_name[LTTNG_SYM_NAME_LEN];
+};
+
+/*
+ * Either addr is used, or symbol_name and offset.
+ */
+struct lttng_kernel_kprobe {
+	uint64_t addr;
+
+	uint64_t offset;
+	char symbol_name[LTTNG_SYM_NAME_LEN];
+};
+
+struct lttng_kernel_function_tracer {
+	char symbol_name[LTTNG_SYM_NAME_LEN];
+};
+
+/*
+ * For syscall tracing, name = '\0' means "enable all".
+ */
+struct lttng_kernel_event {
+	char name[LTTNG_SYM_NAME_LEN];	/* event name */
+	enum lttng_kernel_instrumentation instrumentation;
+	/* Per instrumentation type configuration */
+	union {
+		struct lttng_kernel_kretprobe kretprobe;
+		struct lttng_kernel_kprobe kprobe;
+		struct lttng_kernel_function_tracer ftrace;
+	} u;
+};
+
+struct lttng_kernel_tracer_version {
+	uint32_t version;
+	uint32_t patchlevel;
+	uint32_t sublevel;
+};
+
+enum lttng_kernel_calibrate_type {
+	LTTNG_KERNEL_CALIBRATE_KRETPROBE,
+};
+
+struct lttng_kernel_calibrate {
+	enum lttng_kernel_calibrate_type type;	/* type (input) */
+};
+
+enum lttng_kernel_context_type {
+	LTTNG_KERNEL_CONTEXT_PID		= 0,
+	LTTNG_KERNEL_CONTEXT_PERF_COUNTER	= 1,
+	LTTNG_KERNEL_CONTEXT_PROCNAME		= 2,
+	LTTNG_KERNEL_CONTEXT_PRIO		= 3,
+	LTTNG_KERNEL_CONTEXT_NICE		= 4,
+	LTTNG_KERNEL_CONTEXT_VPID		= 5,
+	LTTNG_KERNEL_CONTEXT_TID		= 6,
+	LTTNG_KERNEL_CONTEXT_VTID		= 7,
+	LTTNG_KERNEL_CONTEXT_PPID		= 8,
+	LTTNG_KERNEL_CONTEXT_VPPID		= 9,
+};
+
+struct lttng_kernel_perf_counter_ctx {
+	uint32_t type;
+	uint64_t config;
+	char name[LTTNG_SYM_NAME_LEN];
+};
+
+struct lttng_kernel_context {
+	enum lttng_kernel_context_type ctx;
+	union {
+		struct lttng_kernel_perf_counter_ctx perf_counter;
+	} u;
+};
+
+/* LTTng file descriptor ioctl */
+#define LTTNG_KERNEL_SESSION			_IO(0xF6, 0x40)
+#define LTTNG_KERNEL_TRACER_VERSION		\
+	_IOR(0xF6, 0x41, struct lttng_kernel_tracer_version)
+#define LTTNG_KERNEL_TRACEPOINT_LIST		_IO(0xF6, 0x42)
+#define LTTNG_KERNEL_WAIT_QUIESCENT		_IO(0xF6, 0x43)
+#define LTTNG_KERNEL_CALIBRATE			\
+	_IOWR(0xF6, 0x44, struct lttng_kernel_calibrate)
+
+/* Session FD ioctl */
+#define LTTNG_KERNEL_METADATA			\
+	_IOW(0xF6, 0x50, struct lttng_kernel_channel)
+#define LTTNG_KERNEL_CHANNEL			\
+	_IOW(0xF6, 0x51, struct lttng_kernel_channel)
+#define LTTNG_KERNEL_SESSION_START		_IO(0xF6, 0x52)
+#define LTTNG_KERNEL_SESSION_STOP		_IO(0xF6, 0x53)
+
+/* Channel FD ioctl */
+#define LTTNG_KERNEL_STREAM			_IO(0xF6, 0x60)
+#define LTTNG_KERNEL_EVENT			\
+	_IOW(0xF6, 0x61, struct lttng_kernel_event)
+
+/* Event and Channel FD ioctl */
+#define LTTNG_KERNEL_CONTEXT			\
+	_IOW(0xF6, 0x70, struct lttng_kernel_context)
+
+/* Event, Channel and Session ioctl */
+#define LTTNG_KERNEL_ENABLE			_IO(0xF6, 0x80)
+#define LTTNG_KERNEL_DISABLE			_IO(0xF6, 0x81)
+
+#endif /* _LTT_DEBUGFS_ABI_H */