tools: Add guest trace agent as a user tool

This patch adds a user tool, "trace agent" for sending trace data of a guest to
a Host in low overhead. This agent has the following functions:
 - splice a page of ring-buffer to read_pipe without memory copying
 - splice the page from write_pipe to virtio-console without memory copying
 - write trace data to stdout by using -o option
 - controlled by start/stop orders from a Host

Changes in v2:
 - Cleanup (change fprintf() to pr_err() and an include guard)

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 75 insertions, 0 deletions

diff --git a/tools/virtio/virtio-trace/trace-agent.h b/tools/virtio/virtio-trace/trace-agent.h
new file mode 100644
index 000000000000..8de79bfeaa73
--- /dev/null
+++ b/tools/virtio/virtio-trace/trace-agent.h
@@ -0,0 +1,75 @@
+#ifndef __TRACE_AGENT_H__
+#define __TRACE_AGENT_H__
+#include <pthread.h>
+#include <stdbool.h>
+
+#define MAX_CPUS        256
+#define PIPE_INIT       (1024*1024)
+
+/*
+ * agent_info - structure managing total information of guest agent
+ * @pipe_size:  size of pipe (default 1MB)
+ * @use_stdout: set to true when o option is added (default false)
+ * @cpus:       total number of CPUs
+ * @ctl_fd:     fd of control path, /dev/virtio-ports/agent-ctl-path
+ * @rw_ti:      structure managing information of read/write threads
+ */
+struct agent_info {
+        unsigned long pipe_size;
+        bool use_stdout;
+        int cpus;
+        int ctl_fd;
+        struct rw_thread_info *rw_ti[MAX_CPUS];
+};
+
+/*
+ * rw_thread_info - structure managing a read/write thread a cpu
+ * @cpu_num:    cpu number operating this read/write thread
+ * @in_fd:      fd of reading trace data path in cpu_num
+ * @out_fd:     fd of writing trace data path in cpu_num
+ * @read_pipe:  fd of read pipe
+ * @write_pipe: fd of write pipe
+ * @pipe_size:  size of pipe (default 1MB)
+ */
+struct rw_thread_info {
+        int cpu_num;
+        int in_fd;
+        int out_fd;
+        int read_pipe;
+        int write_pipe;
+        unsigned long pipe_size;
+};
+
+/* use for stopping rw threads */
+extern bool global_sig_receive;
+
+/* use for notification */
+extern bool global_run_operation;
+extern pthread_mutex_t mutex_notify;
+extern pthread_cond_t cond_wakeup;
+
+/* for controller of read/write threads */
+extern int rw_ctl_init(const char *ctl_path);
+extern void *rw_ctl_loop(int ctl_fd);
+
+/* for trace read/write thread */
+extern void *rw_thread_info_new(void);
+extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path,
+                        bool stdout_flag, unsigned long pipe_size,
+                        struct rw_thread_info *rw_ti);
+extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti);
+
+static inline void *zalloc(size_t size)
+{
+        return calloc(1, size);
+}
+
+#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__)
+#ifdef DEBUG
+#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
+#else
+#define pr_debug(format, ...) do {} while (0)
+#endif
+
+#endif /*__TRACE_AGENT_H__*/