usage: timestamp-based-on-real-time=[on|off]

Instead of using number of instructions executed (which is per vcpu), we
use the wall time for timestamps. This is useful when tracing user mode
programs as well.

Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
 contrib/plugins/uftrace.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/contrib/plugins/uftrace.c b/contrib/plugins/uftrace.c
index ff4dcb4e9bf..6709b38918e 100644
--- a/contrib/plugins/uftrace.c
+++ b/contrib/plugins/uftrace.c
@@ -93,8 +93,28 @@ enum uftrace_record_type {
 static struct qemu_plugin_scoreboard *score;
 static uint64_t trace_sample;
 static bool trace_privilege_level;
+static bool timestamp_based_on_real_time;
 static CpuOps arch_ops;
 
+static uint64_t gettime_ns(void)
+{
+#ifdef _WIN32
+    /*
+     * On Windows, timespec_get is available only with UCRT, but not with
+     * MinGW64 environment. Simplify by using only gettimeofday on this
+     * platform.
+     */
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    uint64_t now_ns = tv.tv_sec * 1000 * 1000 * 1000 + tv.tv_usec * 1000;
+#else
+    struct timespec ts;
+    timespec_get(&ts, TIME_UTC);
+    uint64_t now_ns = ts.tv_sec * 1000 * 1000 * 1000 + ts.tv_nsec;
+#endif
+    return now_ns;
+}
+
 static void uftrace_write_map(bool system_emulation)
 {
     const char *path = "./uftrace.data/sid-0.map";
@@ -453,6 +473,9 @@ static void cpu_set_new_sample(Cpu *cpu, uint64_t timestamp)
 
 static uint64_t cpu_get_timestamp(const Cpu *cpu)
 {
+    if (timestamp_based_on_real_time) {
+        return gettime_ns();
+    }
     return cpu->insn_count;
 }
 
@@ -865,6 +888,12 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
                 fprintf(stderr, "boolean argument parsing failed: %s\n", opt);
                 return -1;
             }
+        } else if (g_strcmp0(tokens[0], "timestamp-based-on-real-time") == 0) {
+            if (!qemu_plugin_bool_parse(tokens[0], tokens[1],
+                                        &timestamp_based_on_real_time)) {
+                fprintf(stderr, "boolean argument parsing failed: %s\n", opt);
+                return -1;
+            }
         } else {
             fprintf(stderr, "option parsing failed: %s\n", opt);
             return -1;
-- 
2.47.2