[PATCH 22/25] contrib/plugins/uftrace: generate additional files for uftrace

["Alex Bennée" <alex.bennee@linaro.org>]

From: Pierrick Bouvier <pierrick.bouvier@linaro.org>

Beyond traces per cpu, uftrace expect to find some specific files.
- info: contains information about machine/program run
  those values are not impacting uftrace behaviour (only reported by
  uftrace info), and we simply added empty strings.
- memory mapping: how every binary is mapped in memory. For system mode,
  we generate an empty mapping (uftrace_symbols.py, coming in future
  commit, will take care of that). For user mode, we copy current
  /proc/self/maps. We don't need to do any special filtering, as
  reported addresses will necessarily concern guest program, and not
  QEMU and its libraries.
- task: list of tasks. We present every vcpu/privilege level as a
  separate process, as it's the best view we can have when generating a
  (visual) chrome trace. Using threads is less convenient in terms of
  UI.

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-ID: <20250902075042.223990-7-pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 contrib/plugins/uftrace.c | 131 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 130 insertions(+), 1 deletion(-)

diff --git a/contrib/plugins/uftrace.c b/contrib/plugins/uftrace.c
index 10abad0673c..2386cc723bc 100644
--- a/contrib/plugins/uftrace.c
+++ b/contrib/plugins/uftrace.c
@@ -118,6 +118,127 @@ static uint64_t gettime_ns(void)
     return now_ns;
 }
 
+static void uftrace_write_map(bool system_emulation)
+{
+    const char *path = "./uftrace.data/sid-0.map";
+
+    if (system_emulation && access(path, F_OK) == 0) {
+        /* do not erase existing map in system emulation, as a custom one might
+         * already have been generated by uftrace_symbols.py */
+        return;
+    }
+
+    FILE *sid_map = fopen(path, "w");
+    g_assert(sid_map);
+
+    if (system_emulation) {
+        fprintf(sid_map,
+                "# map stack on highest address possible, to prevent uftrace\n"
+                "# from considering any kernel address\n");
+        fprintf(sid_map,
+          "ffffffffffff-ffffffffffff rw-p 00000000 00:00 0 [stack]\n");
+    } else {
+        /* in user mode, copy /proc/self/maps instead */
+        FILE *self_map = fopen("/proc/self/maps", "r");
+        g_assert(self_map);
+        for (;;) {
+            int c = fgetc(self_map);
+            if (c == EOF) {
+                break;
+            }
+            fputc(c, sid_map);
+        }
+        fclose(self_map);
+    }
+    fclose(sid_map);
+}
+
+static void uftrace_write_task(const GArray *traces)
+{
+    FILE *task = fopen("./uftrace.data/task.txt", "w");
+    g_assert(task);
+    for (int i = 0; i < traces->len; ++i) {
+        Trace *t = g_array_index(traces, Trace*, i);
+        fprintf(task, "SESS timestamp=0.0 pid=%"PRIu32" sid=0 exename=\"%s\"\n",
+                t->id, t->name->str);
+        fprintf(task, "TASK timestamp=0.0 tid=%"PRIu32" pid=%"PRIu32"\n",
+                t->id, t->id);
+    }
+    fclose(task);
+}
+
+static void uftrace_write_info(const GArray *traces)
+{
+    g_autoptr(GString) taskinfo_tids = g_string_new("taskinfo:tids=");
+    for (int i = 0; i < traces->len; ++i) {
+        Trace *t = g_array_index(traces, Trace*, i);
+        const char *delim = i > 0 ? "," : "";
+        g_string_append_printf(taskinfo_tids, "%s%"PRIu32, delim, t->id);
+    }
+
+    g_autoptr(GString) taskinfo_nr_tid = g_string_new("taskinfo:nr_tid=");
+    g_string_append_printf(taskinfo_nr_tid, "%d", traces->len);
+
+    FILE *info = fopen("./uftrace.data/info", "w");
+    g_assert(info);
+    /*
+     * $ uftrace dump --debug
+     * uftrace file header: magic         = 4674726163652100
+     * uftrace file header: version       = 4
+     * uftrace file header: header size   = 40
+     * uftrace file header: endian        = 1 (little)
+     * uftrace file header: class          = 2 (64 bit)
+     * uftrace file header: features      = 0x1263 (PLTHOOK | ...
+     * uftrace file header: info          = 0x7bff (EXE_NAME | ...
+     *  <0000000000000000>: 46 74 72 61 63 65 21 00  04 00 00 00 28 00 01 02
+     *  <0000000000000010>: 63 12 00 00 00 00 00 00  ff 7b 00 00 00 00 00 00
+     *  <0000000000000020>: 00 04 00 00 00 00 00 00
+     */
+    const uint8_t header[] = {0x46, 0x74, 0x72, 0x61, 0x63, 0x65, 0x21, 0x00,
+                              0x04, 0x00, 0x00, 0x00, 0x28, 0x00, 0x01, 0x02,
+                              0x63, 0x12, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                              0xff, 0x7b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                              0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+    size_t wrote = fwrite(header, sizeof(header), 1, info);
+    g_assert(wrote == 1);
+    const char *info_data[] = {
+        "exename:",
+        "build_id:0000000000000000000000000000000000000000",
+        "exit_status:",
+        "cmdline:",
+        "cpuinfo:lines=2",
+        "cpuinfo:nr_cpus=",
+        "cpuinfo:desc=",
+        "meminfo:",
+        "osinfo:lines=3",
+        "osinfo:kernel=",
+        "osinfo:hostname=",
+        "osinfo:distro=",
+        "taskinfo:lines=2",
+        taskinfo_nr_tid->str,
+        taskinfo_tids->str,
+        "usageinfo:lines=6",
+        "usageinfo:systime=",
+        "usageinfo:usrtime=",
+        "usageinfo:ctxsw=",
+        "usageinfo:maxrss=",
+        "usageinfo:pagefault=",
+        "usageinfo:iops=",
+        "loadinfo:",
+        "record_date:",
+        "elapsed_time:",
+        "pattern_type:regex",
+        "uftrace_version:",
+        "utc_offset:",
+        0};
+    const char **info_data_it = info_data;
+    while (*(info_data_it)) {
+        fprintf(info, "%s\n", *info_data_it);
+        ++info_data_it;
+    }
+    fclose(info);
+}
+
 static Callstack *callstack_new(void)
 {
     Callstack *cs = g_new0(Callstack, 1);
@@ -612,14 +733,22 @@ static void vcpu_end(unsigned int vcpu_index)
 
 static void at_exit(qemu_plugin_id_t id, void *data)
 {
+    bool system_emulation = (bool) data;
+    g_autoptr(GArray) traces = g_array_new(0, 0, sizeof(Trace *));
+
     for (size_t i = 0; i < qemu_plugin_num_vcpus(); ++i) {
         Cpu *cpu = qemu_plugin_scoreboard_find(score, i);
         for (size_t j = 0; j < cpu->traces->len; ++j) {
             Trace *t = g_array_index(cpu->traces, Trace*, j);
             trace_flush(t, true);
+            g_array_append_val(traces, t);
         }
     }
 
+    uftrace_write_map(system_emulation);
+    uftrace_write_info(traces);
+    uftrace_write_task(traces);
+
     for (size_t i = 0; i < qemu_plugin_num_vcpus(); ++i) {
         vcpu_end(i);
     }
@@ -656,7 +785,7 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
 
     score = qemu_plugin_scoreboard_new(sizeof(Cpu));
     qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
-    qemu_plugin_register_atexit_cb(id, at_exit, NULL);
+    qemu_plugin_register_atexit_cb(id, at_exit, (void *) info->system_emulation);
     qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
 
     return 0;
-- 
2.47.3