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>

1 files changed, 101 insertions, 0 deletions

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");
+}