[Qemu-devel] [PATCH v2 10/11] trace-state: [stderr] add support for dynamically enabling/disabling events

[Lluís]

This includes all the control interfaces already provided by the "simple"
backend (i.e., command line, programmatic and monitor).

Signed-off-by: Fabien Chouteau <address@hidden>
Signed-off-by: Lluís Vilanova <address@hidden>
---
 Makefile.objs     |    8 +++++++-
 configure         |    3 +++
 docs/tracing.txt  |    6 ++----
 hmp-commands.hx   |   10 ++++++++--
 monitor.c         |    8 +++++++-
 qemu-config.c     |    7 ++++---
 qemu-options.hx   |    8 +++++++-
 scripts/tracetool |   33 ++++++++++++++++++++++++++++-----
 stderrtrace.c     |   24 ++++++++++++++++++++++++
 stderrtrace.h     |   14 ++++++++++++++
 vl.c              |   11 +++++++++--
 11 files changed, 113 insertions(+), 19 deletions(-)
 create mode 100644 stderrtrace.c
 create mode 100644 stderrtrace.h

diff --git a/Makefile.objs b/Makefile.objs
index c05f5e5..f7cd67b 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -342,15 +342,22 @@ trace-dtrace.o: trace-dtrace.dtrace $(GENERATED_HEADERS)
        $(call quiet-command,dtrace -o $@ -G -s $<, "  GEN trace-dtrace.o")
 
 simpletrace.o: simpletrace.c $(GENERATED_HEADERS)
+stderrtrace.o: stderrtrace.c $(GENERATED_HEADERS)
 
 ifeq ($(TRACE_BACKEND),dtrace)
 trace-obj-y = trace-dtrace.o
 else
 trace-obj-y = trace.o
+
 ifeq ($(TRACE_BACKEND),simple)
 trace-obj-y += simpletrace.o
 user-obj-y += qemu-timer-common.o
 endif
+
+ifeq ($(TRACE_BACKEND),stderr)
+trace-obj-y += stderrtrace.o
+endif
+
 endif
 
 ######################################################################
@@ -361,4 +368,3 @@ libcacard-y = cac.o event.o vcard.o vreader.o 
vcard_emul_nss.o vcard_emul_type.o
 vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
 
 vl.o: QEMU_CFLAGS+=$(SDL_CFLAGS)
-
diff --git a/configure b/configure
index 8754060..7dc9bdc 100755
--- a/configure
+++ b/configure
@@ -2933,6 +2933,9 @@ echo "TRACE_BACKEND=$trace_backend" >> $config_host_mak
 if test "$trace_backend" = "simple"; then
   echo "CONFIG_SIMPLE_TRACE=y" >> $config_host_mak
 fi
+if test "$trace_backend" = "stderr"; then
+  echo "CONFIG_STDERR_TRACE=y" >> $config_host_mak
+fi
 # Set the appropriate trace file.
 if test "$trace_backend" = "simple"; then
   trace_file="\"$trace_file-%u\""
diff --git a/docs/tracing.txt b/docs/tracing.txt
index 26b221f..51fe0ad 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -134,10 +134,8 @@ effectively turns trace events into debug printfs.
 This is the simplest backend and can be used together with existing code that
 uses DPRINTF().
 
-Note that with this backend trace events cannot be programmatically
-enabled/disabled. Thus, in order to trim down the amount of output and the
-performance impact of tracing, you might want to add the "disable" property in
-the "trace-events" file for those events you are not interested in.
+See the documentation in the "simple" backend for instruction on how to control
+trace event states from the command line, the monitor and/or programmatically.
 
 === Simpletrace ===
 
diff --git a/hmp-commands.hx b/hmp-commands.hx
index c3be311..7cca351 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -180,7 +180,7 @@ STEXI
 Output logs to @var{filename}.
 ETEXI
 
-#ifdef CONFIG_SIMPLE_TRACE
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
     {
         .name       = "trace-event",
         .args_type  = "name:s,option:b",
@@ -194,7 +194,9 @@ STEXI
 @findex trace-event
 changes status of a trace event
 ETEXI
+#endif
 
+#if defined(CONFIG_SIMPLE_TRACE)
     {
         .name       = "trace-file",
         .args_type  = "op:s?,arg:F?",
@@ -1355,10 +1357,14 @@ show roms
 @end table
 ETEXI
 
-#ifdef CONFIG_SIMPLE_TRACE
+#if defined(CONFIG_SIMPLE_TRACE)
 STEXI
 @item info trace
 show contents of trace buffer
+ETEXI
+#endif
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
+STEXI
 @item info trace-events
 show available trace events and their state
 ETEXI
diff --git a/monitor.c b/monitor.c
index 377424e..7991c6c 100644
--- a/monitor.c
+++ b/monitor.c
@@ -590,7 +590,7 @@ static void do_help_cmd(Monitor *mon, const QDict *qdict)
     help_cmd(mon, qdict_get_try_str(qdict, "name"));
 }
 
-#if defined(CONFIG_SIMPLE_TRACE)
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
 static void do_change_trace_event_state(Monitor *mon, const QDict *qdict)
 {
     const char *tp_name = qdict_get_str(qdict, "name");
@@ -601,7 +601,9 @@ static void do_change_trace_event_state(Monitor *mon, const 
QDict *qdict)
         monitor_printf(mon, "unknown event name \"%s\"\n", tp_name);
     }
 }
+#endif
 
+#if defined(CONFIG_SIMPLE_TRACE)
 static void do_trace_file(Monitor *mon, const QDict *qdict)
 {
     const char *op = qdict_get_try_str(qdict, "op");
@@ -999,7 +1001,9 @@ static void do_info_trace(Monitor *mon)
 {
     st_print_trace((FILE *)mon, &monitor_fprintf);
 }
+#endif
 
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
 static void do_info_trace_events(Monitor *mon)
 {
     st_print_trace_events((FILE *)mon, &monitor_fprintf);
@@ -3103,6 +3107,8 @@ static const mon_cmd_t info_cmds[] = {
         .help       = "show current contents of trace buffer",
         .mhandler.info = do_info_trace,
     },
+#endif
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
     {
         .name       = "trace-events",
         .args_type  = "",
diff --git a/qemu-config.c b/qemu-config.c
index 7c7357f..7a20971 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -297,7 +297,7 @@ static QemuOptsList qemu_mon_opts = {
     },
 };
 
-#if defined(CONFIG_SIMPLE_TRACE)
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
 static QemuOptsList qemu_trace_opts = {
     .name = "trace",
     .implied_opt_name = "trace",
@@ -306,7 +306,8 @@ static QemuOptsList qemu_trace_opts = {
         {
             .name = "file",
             .type = QEMU_OPT_STRING,
-        },{
+        },
+        {
             .name = "events",
             .type = QEMU_OPT_STRING,
         },
@@ -464,7 +465,7 @@ static QemuOptsList *vm_config_groups[32] = {
     &qemu_global_opts,
     &qemu_mon_opts,
     &qemu_cpudef_opts,
-#if defined(CONFIG_SIMPLE_TRACE)
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
     &qemu_trace_opts,
 #endif
     &qemu_option_rom_opts,
diff --git a/qemu-options.hx b/qemu-options.hx
index ff8e75d..1bcc27b 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2356,9 +2356,13 @@ Normally QEMU loads a configuration file from 
@var{sysconfdir}/qemu.conf and
 @var{sysconfdir}/address@hidden on startup.  The @code{-nodefconfig}
 option will prevent QEMU from loading these configuration files at startup.
 ETEXI
-#ifdef CONFIG_SIMPLE_TRACE
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
+#if defined(CONFIG_SIMPLE_TRACE)
     "-trace [file=<file>][,events=<file>]\n"
+#elif defined(CONFIG_STDERR_TRACE)
+    "-trace [events=<file>]\n"
+#endif
     "                specify tracing options\n",
     QEMU_ARCH_ALL)
 STEXI
@@ -2368,7 +2372,9 @@ STEXI
 Specify tracing options.
 
 @table @option
+#if defined(CONFIG_SIMPLE_TRACE)
 @item address@hidden
+#endif
 Log output traces to @var{file}.
 @item address@hidden
 Immediately enable events listed in @var{file}.
diff --git a/scripts/tracetool b/scripts/tracetool
index e3aec89..17e3f37 100755
--- a/scripts/tracetool
+++ b/scripts/tracetool
@@ -241,7 +241,12 @@ linetoh_begin_stderr()
 {
     cat <<EOF
 #include <stdio.h>
+#include "stderrtrace.h"
+
+extern TraceEvent trace_list[];
 EOF
+
+    stderr_event_num=0
 }
 
 linetoh_stderr()
@@ -260,29 +265,47 @@ linetoh_stderr()
     cat <<EOF
 static inline void trace_$name($args)
 {
-    fprintf(stderr, "$name $fmt\n" $argnames);
+    if (trace_list[$stderr_event_num].state != 0) {
+        fprintf(stderr, "$name $fmt\n" $argnames);
+    }
 }
 EOF
+    stderr_event_num=$((stderr_event_num + 1))
+
 }
 
 linetoh_end_stderr()
 {
-return
+    cat <<EOF
+#define NR_TRACE_EVENTS $stderr_event_num
+EOF
 }
 
 linetoc_begin_stderr()
 {
-return
+    cat <<EOF
+#include "trace.h"
+
+TraceEvent trace_list[] = {
+EOF
+    stderr_event_num=0
 }
 
 linetoc_stderr()
 {
-return
+    local name
+    name=$(get_name "$1")
+    cat <<EOF
+{.tp_name = "$name", .state=0},
+EOF
+    stderr_event_num=$(($stderr_event_num + 1))
 }
 
 linetoc_end_stderr()
 {
-return
+    cat <<EOF
+};
+EOF
 }
 #END OF STDERR
 
diff --git a/stderrtrace.c b/stderrtrace.c
new file mode 100644
index 0000000..dac373c
--- /dev/null
+++ b/stderrtrace.c
@@ -0,0 +1,24 @@
+#include "trace.h"
+
+void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, 
const char *fmt, ...))
+{
+    unsigned int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        stream_printf(stream, "%s [Event ID %u] : state %u\n",
+                      trace_list[i].tp_name, i, trace_list[i].state);
+    }
+}
+
+bool st_change_trace_event_state(const char *name, bool enabled)
+{
+    int i;
+
+    for (i = 0; i < NR_TRACE_EVENTS; i++) {
+        if (!strcmp(trace_list[i].tp_name, name)) {
+            trace_list[i].state = enabled;
+            return true;
+        }
+    }
+    return false;
+}
diff --git a/stderrtrace.h b/stderrtrace.h
new file mode 100644
index 0000000..48ac36a
--- /dev/null
+++ b/stderrtrace.h
@@ -0,0 +1,14 @@
+#ifndef _STDERRTRACE_H_
+#define _STDERRTRACE_H_
+
+typedef uint64_t TraceEventID;
+
+typedef struct {
+    const char *tp_name;
+    bool state;
+} TraceEvent;
+
+void st_print_trace_events(FILE *stream, fprintf_function stream_printf);
+bool st_change_trace_event_state(const char *name, bool enabled);
+
+#endif /* ! _STDERRTRACE_H_ */
diff --git a/vl.c b/vl.c
index 35d440d..67dc530 100644
--- a/vl.c
+++ b/vl.c
@@ -1966,7 +1966,7 @@ int main(int argc, char **argv, char **envp)
     int show_vnc_port = 0;
 #endif
     int defconfig = 1;
-#if defined(CONFIG_SIMPLE_TRACE)
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
     const char *trace_file = NULL;
     const char *trace_events_file = NULL;
 #endif
@@ -2762,7 +2762,7 @@ int main(int argc, char **argv, char **envp)
                 }
                 xen_mode = XEN_ATTACH;
                 break;
-#if defined(CONFIG_SIMPLE_TRACE)
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
             case QEMU_OPTION_trace:
                 opts = qemu_opts_parse(qemu_find_opts("trace"), optarg, 0);
                 if (opts) {
@@ -2820,6 +2820,13 @@ int main(int argc, char **argv, char **envp)
     if (!st_init(trace_file)) {
         fprintf(stderr, "warning: unable to initialize simple trace 
backend\n");
     }
+#else
+    if (trace_file) {
+        fprintf(stderr, "option \"-trace file=\" not supported\n");
+        exit(1);
+    }
+#endif
+#if defined(CONFIG_SIMPLE_TRACE) || defined(CONFIG_STDERR_TRACE)
     if (trace_events_file) {
         FILE *trace_events_fp = fopen(trace_events_file, "r");
         if (!trace_events_fp) {