Add DTrace support to xenstored

Add USDT probes for significant xenstore operations to allow dynamic
tracing.

Signed-off-by: John Levon <john.levon@sun.com>

5 files changed, 154 insertions, 8 deletions

diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile
index 3d6700c0b8..bf0ae4ed64 100644
--- a/tools/xenstore/Makefile
+++ b/tools/xenstore/Makefile
@@ -24,7 +24,7 @@ CLIENTS_OBJS := $(patsubst xenstore-%,xenstore_%.o,$(CLIENTS))
 XENSTORED_OBJS = xenstored_core.o xenstored_watch.o xenstored_domain.o xenstored_transaction.o xs_lib.o talloc.o utils.o tdb.o hashtable.o
 
 XENSTORED_OBJS_$(CONFIG_Linux) = xenstored_linux.o
-XENSTORED_OBJS_$(CONFIG_SunOS) = xenstored_solaris.o
+XENSTORED_OBJS_$(CONFIG_SunOS) = xenstored_solaris.o xenstored_probes.o
 XENSTORED_OBJS_$(CONFIG_NetBSD) = xenstored_netbsd.o
 
 XENSTORED_OBJS += $(XENSTORED_OBJS_y)
@@ -32,6 +32,18 @@ XENSTORED_OBJS += $(XENSTORED_OBJS_y)
 .PHONY: all
 all: libxenstore.so libxenstore.a xenstored $(CLIENTS) xs_tdb_dump xenstore-control xenstore-ls
 
+ifeq ($(CONFIG_SunOS),y)
+xenstored_probes.h: xenstored_probes.d
+	dtrace -C -h -s xenstored_probes.d
+
+xenstored_solaris.o: xenstored_probes.h
+
+xenstored_probes.o: xenstored_solaris.o
+	dtrace -C -G -s xenstored_probes.d xenstored_solaris.o 
+
+CFLAGS += -DHAVE_DTRACE=1
+endif
+ 
 xenstored: $(XENSTORED_OBJS)
 	$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LOADLIBES) $(LDLIBS) $(LDFLAGS_libxenctrl) $(SOCKET_LIBS) -o $@
 
@@ -63,7 +75,7 @@ libxenstore.a: xs.o xs_lib.o
 
 .PHONY: clean
 clean:
-	rm -f *.a *.o *.opic *.so*
+	rm -f *.a *.o *.opic *.so* xenstored_probes.h
 	rm -f xenstored xs_random xs_stress xs_crashme
 	rm -f xs_tdb_dump xenstore-control xenstore-ls
 	rm -f $(CLIENTS)
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 7f20e30ca0..a643f2d969 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -154,20 +154,25 @@ void trace(const char *fmt, ...)
 }
 
 static void trace_io(const struct connection *conn,
-		     const char *prefix,
-		     const struct buffered_data *data)
+		     const struct buffered_data *data,
+		     int out)
 {
 	unsigned int i;
 	time_t now;
 	struct tm *tm;
 
+#ifdef HAVE_DTRACE
+	dtrace_io(conn, data, out);
+#endif
+
 	if (tracefd < 0)
 		return;
 
 	now = time(NULL);
 	tm = localtime(&now);
 
-	trace("%s %p %04d%02d%02d %02d:%02d:%02d %s (", prefix, conn,
+	trace("%s %p %04d%02d%02d %02d:%02d:%02d %s (",
+	      out ? "OUT" : "IN", conn,
 	      tm->tm_year + 1900, tm->tm_mon + 1,
 	      tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec,
 	      sockmsg_string(data->hdr.msg.type));
@@ -257,7 +262,7 @@ static bool write_messages(struct connection *conn)
 	if (out->used != out->hdr.msg.len)
 		return true;
 
-	trace_io(conn, "OUT", out);
+	trace_io(conn, out, 1);
 
 	list_del(&out->list);
 	talloc_free(out);
@@ -1316,7 +1321,7 @@ static void handle_input(struct connection *conn)
 	if (in->used != in->hdr.msg.len)
 		return;
 
-	trace_io(conn, "IN ", in);
+	trace_io(conn, in, 0);
 	consider_message(conn);
 	return;
 
diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
index 975a97226f..c487089c2f 100644
--- a/tools/xenstore/xenstored_core.h
+++ b/tools/xenstore/xenstored_core.h
@@ -160,12 +160,12 @@ struct connection *new_connection(connwritefn_t *write, connreadfn_t *read);
 /* Is this a valid node name? */
 bool is_valid_nodename(const char *node);
 
-
 /* Tracing infrastructure. */
 void trace_create(const void *data, const char *type);
 void trace_destroy(const void *data, const char *type);
 void trace_watch_timeout(const struct connection *conn, const char *node, const char *token);
 void trace(const char *fmt, ...);
+void dtrace_io(const struct connection *conn, const struct buffered_data *data, int out);
 
 extern int event_fd;
 
diff --git a/tools/xenstore/xenstored_probes.d b/tools/xenstore/xenstored_probes.d
new file mode 100644
index 0000000000..f72d38f935
--- /dev/null
+++ b/tools/xenstore/xenstored_probes.d
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ */
+
+#include <sys/types.h>
+
+provider xenstore {
+	/* tx id, dom id, pid, type, msg */
+	probe msg(uint32_t, unsigned int, pid_t, int, const char *);
+	/* tx id, dom id, pid, type, reply */
+	probe reply(uint32_t, unsigned int, pid_t, int, const char *);
+	/* tx id, dom id, pid, reply */
+	probe error(uint32_t, unsigned int, pid_t, const char *);
+	/* dom id, pid, watch details */
+	probe watch_event(unsigned int, pid_t, const char *);
+};
+
+#pragma D attributes Evolving/Evolving/Common provider xenstore provider
+#pragma D attributes Private/Private/Unknown provider xenstore module
+#pragma D attributes Private/Private/Unknown provider xenstore function
+#pragma D attributes Evolving/Evolving/Common provider xenstore name
+#pragma D attributes Evolving/Evolving/Common provider xenstore args
+
diff --git a/tools/xenstore/xenstored_solaris.c b/tools/xenstore/xenstored_solaris.c
index 376a00081b..ef6b51533c 100644
--- a/tools/xenstore/xenstored_solaris.c
+++ b/tools/xenstore/xenstored_solaris.c
@@ -15,9 +15,15 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <sys/mman.h>
+#include <strings.h>
+#include <ucred.h>
+#include <stdio.h>
+
 #include <xen/sys/xenbus.h>
 
+#include "talloc.h"
 #include "xenstored_core.h"
+#include "xenstored_probes.h"
 
 evtchn_port_t xenbus_evtchn(void)
 {
@@ -64,3 +70,98 @@ void xenbus_notify_running(void)
 
 	close(fd);
 }
+
+static pid_t cred(const struct connection *conn)
+{
+	ucred_t *ucred = NULL;
+	pid_t pid;
+
+	if (conn->domain)
+		return (0);
+
+	if (getpeerucred(conn->fd, &ucred) == -1)
+		return (0);
+
+	pid = ucred_getpid(ucred);
+
+	ucred_free(ucred);
+	return (pid);
+}
+
+/*
+ * The strings are often a number of nil-separated strings. We'll just
+ * replace the separators with spaces - not quite right, but good
+ * enough.
+ */
+static char *
+mangle(const struct connection *conn, const struct buffered_data *in)
+{
+	char *str;
+	int i;
+
+	if (in->hdr.msg.len == 0)
+		return (talloc_strdup(conn, ""));
+
+	if ((str = talloc_zero_size(conn, in->hdr.msg.len + 1)) == NULL)
+		return (NULL);
+
+	memcpy(str, in->buffer, in->hdr.msg.len);
+	
+	/*
+	 * The protocol is absurdly inconsistent in whether the length
+	 * includes the terminating nil or not; replace all nils that
+	 * aren't the last one.
+	 */
+	for (i = 0; i < (in->hdr.msg.len - 1); i++) {
+		if (str[i] == '\0')
+			str[i] = ' ';
+	}
+
+	return (str);
+}
+
+void
+dtrace_io(const struct connection *conn, const struct buffered_data *in,
+    int io_out)
+{
+	if (!io_out) {
+		if (XENSTORE_MSG_ENABLED()) {
+			char *mangled = mangle(conn, in);
+			XENSTORE_MSG(in->hdr.msg.tx_id, conn->id, cred(conn),
+			    in->hdr.msg.type, mangled);
+		}
+
+		goto out;
+	}
+
+	switch (in->hdr.msg.type) {
+	case XS_ERROR:
+		if (XENSTORE_ERROR_ENABLED()) {
+			char *mangled = mangle(conn, in);
+			XENSTORE_ERROR(in->hdr.msg.tx_id, conn->id,
+			    cred(conn), mangled);
+		}
+		break;
+
+	case XS_WATCH_EVENT:
+		if (XENSTORE_WATCH_EVENT_ENABLED()) {
+			char *mangled = mangle(conn, in);
+			XENSTORE_WATCH_EVENT(conn->id, cred(conn), mangled);
+		}
+		break;
+
+	default:
+		if (XENSTORE_REPLY_ENABLED()) {
+			char *mangled = mangle(conn, in);
+			XENSTORE_REPLY(in->hdr.msg.tx_id, conn->id, cred(conn),
+			    in->hdr.msg.type, mangled);
+		}
+		break;
+	}
+
+out:
+	/*
+	 * 6589130 dtrace -G fails for certain tail-calls on x86
+	 */
+	asm("nop");
+}