Merge remote-tracking branch 'stefanha/tracing' into staging

# By Eiichi Tsukata (2) and Kazuya Saito (2)
# Via Stefan Hajnoczi
* stefanha/tracing:
  trace: document ftrace backend
  trace: Add ftrace tracing backend
  kvm-all: add kvm_run_exit tracepoint
  kvm-all: add kvm_ioctl, kvm_vm_ioctl, kvm_vcpu_ioctl tracepoints

Message-id: 1367582485-15579-1-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

configure

@@ -4004,6 +4004,14 @@ if test "$trace_backend" = "dtrace"; then
     echo "CONFIG_TRACE_SYSTEMTAP=y" >> $config_host_mak
   fi
 fi
+if test "$trace_backend" = "ftrace"; then
+  if test "$linux" = "yes" ; then
+    echo "CONFIG_TRACE_FTRACE=y" >> $config_host_mak
+    trace_default=no
+  else
+    feature_not_found "ftrace(trace backend)"
+  fi
+fi
 echo "CONFIG_TRACE_FILE=$trace_file" >> $config_host_mak
 if test "$trace_default" = "yes"; then
   echo "CONFIG_TRACE_DEFAULT=y" >> $config_host_mak

docs/tracing.txt

@@ -175,6 +175,22 @@ unless you have specific needs for more advanced backends.
 The "simple" backend currently does not capture string arguments, it simply
 records the char* pointer value instead of the string that is pointed to.
 
+=== Ftrace ===
+
+The "ftrace" backend writes trace data to ftrace marker. This effectively
+sends trace events to ftrace ring buffer, and you can compare qemu trace
+data and kernel(especially kvm.ko when using KVM) trace data.
+
+if you use KVM, enable kvm events in ftrace:
+
+   # echo 1 > /sys/kernel/debug/tracing/events/kvm/enable
+
+After running qemu by root user, you can get the trace:
+
+   # cat /sys/kernel/debug/tracing/trace
+
+Restriction: "ftrace" backend is restricted to Linux only.
+
 ==== Monitor commands ====
 
 * trace-file on|off|flush|set <path>

kvm-all.c

@@ -33,6 +33,7 @@
 #include "exec/memory.h"
 #include "exec/address-spaces.h"
 #include "qemu/event_notifier.h"
+#include "trace.h"
 
 /* This check must be after config-host.h is included */
 #ifdef CONFIG_EVENTFD
@@ -1626,6 +1627,7 @@ int kvm_cpu_exec(CPUArchState *env)
             abort();
         }
 
+        trace_kvm_run_exit(cpu->cpu_index, run->exit_reason);
         switch (run->exit_reason) {
         case KVM_EXIT_IO:
             DPRINTF("handle_io\n");
@@ -1687,6 +1689,7 @@ int kvm_ioctl(KVMState *s, int type, ...)
     arg = va_arg(ap, void *);
     va_end(ap);
 
+    trace_kvm_ioctl(type, arg);
     ret = ioctl(s->fd, type, arg);
     if (ret == -1) {
         ret = -errno;
@@ -1704,6 +1707,7 @@ int kvm_vm_ioctl(KVMState *s, int type, ...)
     arg = va_arg(ap, void *);
     va_end(ap);
 
+    trace_kvm_vm_ioctl(type, arg);
     ret = ioctl(s->vmfd, type, arg);
     if (ret == -1) {
         ret = -errno;
@@ -1721,6 +1725,7 @@ int kvm_vcpu_ioctl(CPUState *cpu, int type, ...)
     arg = va_arg(ap, void *);
     va_end(ap);
 
+    trace_kvm_vcpu_ioctl(cpu->cpu_index, type, arg);
     ret = ioctl(cpu->kvm_fd, type, arg);
     if (ret == -1) {
         ret = -errno;

scripts/tracetool/backend/ftrace.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Ftrace built-in backend.
+"""
+
+__author__     = "Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>"
+__copyright__  = "Copyright (C) 2013 Hitachi, Ltd."
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@redhat.com"
+
+
+from tracetool import out
+
+
+PUBLIC = True
+
+
+def c(events):
+    pass
+
+def h(events):
+    out('#include "trace/ftrace.h"',
+        '#include "trace/control.h"',
+        '',
+        )
+
+    for e in events:
+        argnames = ", ".join(e.args.names())
+        if len(e.args) > 0:
+            argnames = ", " + argnames
+
+        out('static inline void trace_%(name)s(%(args)s)',
+            '{',
+            '    char ftrace_buf[MAX_TRACE_STRLEN];',
+            '    int unused __attribute__ ((unused));',
+            '    int trlen;',
+            '    bool _state = trace_event_get_state(%(event_id)s);',
+            '    if (_state) {',
+            '        trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
+            '                         "%(name)s " %(fmt)s "\\n" %(argnames)s);',
+            '        trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
+            '        unused = write(trace_marker_fd, ftrace_buf, trlen);',
+            '    }',
+            '}',
+            name = e.name,
+            args = e.args,
+            event_id = "TRACE_" + e.name.upper(),
+            fmt = e.fmt.rstrip("\n"),
+            argnames = argnames,
+            )

trace-events

@@ -1153,3 +1153,10 @@ virtio_ccw_new_device(int cssid, int ssid, int schid, int devno, const char *dev
 
 # migration.c
 migrate_set_state(int new_state) "new state %d"
+
+# kvm-all.c
+kvm_ioctl(int type, void *arg) "type %d, arg %p"
+kvm_vm_ioctl(int type, void *arg) "type %d, arg %p"
+kvm_vcpu_ioctl(int cpu_index, int type, void *arg) "cpu_index %d, type %d, arg %p"
+kvm_run_exit(int cpu_index, uint32_t reason) "cpu_index %d, reason %d"
+

trace/Makefile.objs

@@ -76,5 +76,6 @@ endif
 util-obj-$(CONFIG_TRACE_DEFAULT) += default.o
 util-obj-$(CONFIG_TRACE_SIMPLE) += simple.o
 util-obj-$(CONFIG_TRACE_STDERR) += stderr.o
+util-obj-$(CONFIG_TRACE_FTRACE) += ftrace.o
 util-obj-y += control.o
 util-obj-y += generated-tracers.o

trace/ftrace.c

@@ -0,0 +1,102 @@
+/*
+ * Ftrace trace backend
+ *
+ * Copyright (C) 2013 Hitachi, Ltd.
+ * Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <limits.h>
+#include "trace.h"
+#include "trace/control.h"
+
+int trace_marker_fd;
+
+static int find_debugfs(char *debugfs)
+{
+    char type[100];
+    FILE *fp;
+
+    fp = fopen("/proc/mounts", "r");
+    if (fp == NULL) {
+        return 0;
+    }
+
+    while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+                  debugfs, type) == 2) {
+        if (strcmp(type, "debugfs") == 0) {
+            break;
+        }
+    }
+    fclose(fp);
+
+    if (strcmp(type, "debugfs") != 0) {
+        return 0;
+    }
+    return 1;
+}
+
+void trace_print_events(FILE *stream, fprintf_function stream_printf)
+{
+    TraceEventID i;
+
+    for (i = 0; i < trace_event_count(); i++) {
+        TraceEvent *ev = trace_event_id(i);
+        stream_printf(stream, "%s [Event ID %u] : state %u\n",
+                      trace_event_get_name(ev), i, trace_event_get_state_dynamic(ev));
+    }
+}
+
+void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
+{
+    ev->dstate = state;
+}
+
+bool trace_backend_init(const char *events, const char *file)
+{
+    char debugfs[PATH_MAX];
+    char path[PATH_MAX];
+    int debugfs_found;
+    int trace_fd = -1;
+
+    if (file) {
+        fprintf(stderr, "error: -trace file=...: "
+                "option not supported by the selected tracing backend\n");
+        return false;
+    }
+
+    debugfs_found = find_debugfs(debugfs);
+    if (debugfs_found) {
+        snprintf(path, PATH_MAX, "%s/tracing/tracing_on", debugfs);
+        trace_fd = open(path, O_WRONLY);
+        if (trace_fd < 0) {
+            perror("Could not open ftrace 'tracing_on' file");
+            return false;
+        } else {
+            if (write(trace_fd, "1", 1) < 0) {
+                perror("Could not write to 'tracing_on' file");
+                close(trace_fd);
+                return false;
+            }
+            close(trace_fd);
+        }
+        snprintf(path, PATH_MAX, "%s/tracing/trace_marker", debugfs);
+        trace_marker_fd = open(path, O_WRONLY);
+        if (trace_marker_fd < 0) {
+            perror("Could not open ftrace 'trace_marker' file");
+            return false;
+        }
+    } else {
+        fprintf(stderr, "debugfs is not mounted\n");
+        return false;
+    }
+
+    trace_backend_init_events(events);
+    return true;
+}

trace/ftrace.h

@@ -0,0 +1,10 @@
+#ifndef TRACE_FTRACE_H
+#define TRACE_FTRACE_H
+
+#define MAX_TRACE_STRLEN 512
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+extern int trace_marker_fd;
+
+#endif /* ! TRACE_FTRACE_H */