Make calls to the plugin, recursion-safe

loader/proxy_funcs.c

@@ -20,10 +20,19 @@
 // plugin libraries that use malloc, pthreads, etc will work in harmony with the
 // client.
 
+// TODO(andronat): What should we do with the flags after a clone()?
+static _Thread_local bool from_plugin_sc_handler = false;
+
 long proxy_plugin_sc_handler(long sc_no, long arg1, long arg2, long arg3,
                              long arg4, long arg5, long arg6,
                              void *wrapper_sp) {
+  if (from_plugin_sc_handler == true) {
+    from_plugin_sc_handler = false;
+    return syscall(sc_no, arg1, arg2, arg3, arg4, arg5, arg6);
+  }
+
   load_sabre_tls();
+  from_plugin_sc_handler = true;
   long fd =
       plugin_sc_handler(sc_no, arg1, arg2, arg3, arg4, arg5, arg6, wrapper_sp);
   load_client_tls();
@@ -32,8 +41,17 @@ long proxy_plugin_sc_handler(long sc_no, long arg1, long arg2, long arg3,
 
 typedef long clock_gettime_fn(clockid_t, struct timespec *);
 static clock_gettime_fn *plugin_vdso_clock_gettime;
+static clock_gettime_fn *real_vdso_clock_gettime;
+static _Thread_local bool from_plugin_vdso_clock_gettime = false;
+
 long proxy_vdso_clock_gettime(clockid_t arg1, struct timespec *arg2) {
+  if (from_plugin_vdso_clock_gettime == true) {
+    from_plugin_vdso_clock_gettime = false;
+    return real_vdso_clock_gettime(arg1, arg2);
+  }
+
   load_sabre_tls();
+  from_plugin_vdso_clock_gettime = true;
   long ret = plugin_vdso_clock_gettime(arg1, arg2);
   load_client_tls();
   return ret;
@@ -42,17 +60,35 @@ long proxy_vdso_clock_gettime(clockid_t arg1, struct timespec *arg2) {
 // arg3 has type: struct getcpu_cache *
 typedef long getcpu_fn(unsigned *, unsigned *, void *);
 static getcpu_fn *plugin_vdso_getcpu;
+static getcpu_fn *real_vdso_getcpu;
+static _Thread_local bool from_plugin_vdso_getcpu = false;
+
 long proxy_vdso_getcpu(unsigned *arg1, unsigned *arg2, void *arg3) {
+  if (from_plugin_vdso_getcpu == true) {
+    from_plugin_vdso_getcpu = false;
+    return real_vdso_getcpu(arg1, arg2, arg3);
+  }
+
   load_sabre_tls();
+  from_plugin_vdso_getcpu = true;
   long ret = plugin_vdso_getcpu(arg1, arg2, arg3);
   load_client_tls();
   return ret;
 }
 
 typedef long gettimeofday_fn(struct timeval *, struct timezone *);
 static gettimeofday_fn *plugin_vdso_gettimeofday;
+static gettimeofday_fn *real_vdso_gettimeofday;
+static _Thread_local bool from_plugin_vdso_gettimeofday = false;
+
 long proxy_vdso_gettimeofday(struct timeval *arg1, struct timezone *arg2) {
+  if (from_plugin_vdso_gettimeofday == true) {
+    from_plugin_vdso_gettimeofday = false;
+    return real_vdso_gettimeofday(arg1, arg2);
+  }
+
   load_sabre_tls();
+  from_plugin_vdso_gettimeofday = true;
   long ret = plugin_vdso_gettimeofday(arg1, arg2);
   load_client_tls();
   return ret;
@@ -61,8 +97,17 @@ long proxy_vdso_gettimeofday(struct timeval *arg1, struct timezone *arg2) {
 #ifdef __x86_64__
 typedef long time_fn(time_t *);
 static time_fn *plugin_vdso_time;
+static time_fn *real_vdso_time;
+static _Thread_local bool from_plugin_vdso_time = false;
+
 long proxy_vdso_time(time_t *arg1) {
+  if (from_plugin_vdso_time == true) {
+    from_plugin_vdso_time = false;
+    return real_vdso_time(arg1);
+  }
+
   load_sabre_tls();
+  from_plugin_vdso_time = true;
   long ret = plugin_vdso_time(arg1);
   load_client_tls();
   return ret;
@@ -72,24 +117,28 @@ long proxy_vdso_time(time_t *arg1) {
 void_void_fn proxy_vdso_callback(long sc_no, void_void_fn actual_fn) {
   switch (sc_no) {
   case SYS_clock_gettime:
+    real_vdso_clock_gettime = (clock_gettime_fn *)actual_fn;
     plugin_vdso_clock_gettime =
         (clock_gettime_fn *)vdso_callback(sc_no, actual_fn);
     if (plugin_vdso_clock_gettime == NULL)
       return NULL;
     return (void_void_fn)proxy_vdso_clock_gettime;
   case SYS_getcpu:
+    real_vdso_getcpu = (getcpu_fn *)actual_fn;
     plugin_vdso_getcpu = (getcpu_fn *)vdso_callback(sc_no, actual_fn);
     if (plugin_vdso_getcpu == NULL)
       return NULL;
     return (void_void_fn)proxy_vdso_getcpu;
   case SYS_gettimeofday:
+    real_vdso_gettimeofday = (gettimeofday_fn *)actual_fn;
     plugin_vdso_gettimeofday =
         (gettimeofday_fn *)vdso_callback(sc_no, actual_fn);
     if (plugin_vdso_gettimeofday == NULL)
       return NULL;
     return (void_void_fn)proxy_vdso_gettimeofday;
 #ifdef __x86_64__
   case SYS_time:
+    real_vdso_time = (time_fn *)actual_fn;
     plugin_vdso_time = (time_fn *)vdso_callback(sc_no, actual_fn);
     if (plugin_vdso_time == NULL)
       return NULL;