elf/tst-tls-ie.c

   1 /* Test dlopen of modules with initial-exec TLS.
   2    Copyright (C) 2016-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* This test tries to check that surplus static TLS is not used up for
  20    dynamic TLS optimizations and 3*192 + 4*144 = 1152 bytes of static
  21    TLS is available for dlopening modules with initial-exec TLS.  It
  22    depends on rtld.nns=4 and rtld.optional_static_tls=512 tunable setting.  */
  23
  24 #include <errno.h>
  25 #include <pthread.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29
  30 static int do_test (void);
  31 #include <support/xthread.h>
  32 #include <support/xdlfcn.h>
  33 #include <support/check.h>
  34 #include <support/test-driver.c>
  35
  36 /* Have some big TLS in the main exe: should not use surplus TLS.  */
  37 __thread char maintls[1000];
  38
  39 static pthread_barrier_t barrier;
  40
  41 /* Forces multi-threaded behaviour.  */
  42 static void *
  43 blocked_thread_func (void *closure)
  44 {
  45   xpthread_barrier_wait (&barrier);
  46   /* TLS load and access tests run here in the main thread.  */
  47   xpthread_barrier_wait (&barrier);
  48   return NULL;
  49 }
  50
  51 static void *
  52 load_and_access (const char *mod, const char *func)
  53 {
  54   /* Load module with TLS.  */
  55   void *p = xdlopen (mod, RTLD_NOW);
  56   /* Access the TLS variable to ensure it is allocated.  */
  57   void (*f) (void) = (void (*) (void))xdlsym (p, func);
  58   f ();
  59   return p;
  60 }
  61
  62 static int
  63 do_test (void)
  64 {
  65   void *mods[6];
  66
  67   {
  68     int ret = pthread_barrier_init (&barrier, NULL, 2);
  69     if (ret != 0)
  70       {
  71         errno = ret;
  72         printf ("error: pthread_barrier_init: %m\n");
  73         exit (1);
  74       }
  75   }
  76
  77   pthread_t blocked_thread = xpthread_create (NULL, blocked_thread_func, NULL);
  78   xpthread_barrier_wait (&barrier);
  79
  80   printf ("maintls[%zu]:\t %p .. %p\n",
  81            sizeof maintls, maintls, maintls + sizeof maintls);
  82   memset (maintls, 1, sizeof maintls);
  83
  84   /* Load modules with dynamic TLS (may use surplus static TLS
  85      opportunistically).  */
  86   mods[0] = load_and_access ("tst-tls-ie-mod0.so", "access0");
  87   mods[1] = load_and_access ("tst-tls-ie-mod1.so", "access1");
  88   mods[2] = load_and_access ("tst-tls-ie-mod2.so", "access2");
  89   mods[3] = load_and_access ("tst-tls-ie-mod3.so", "access3");
  90   /* Load modules with initial-exec TLS (can only use surplus static TLS).  */
  91   mods[4] = load_and_access ("tst-tls-ie-mod4.so", "access4");
  92   mods[5] = load_and_access ("tst-tls-ie-mod5.so", "access5");
  93
  94   /* Here 1152 bytes of surplus static TLS is in use and at most 512 bytes
  95      are available (depending on TLS optimizations).  */
  96   printf ("The next dlopen should fail...\n");
  97   void *p = dlopen ("tst-tls-ie-mod6.so", RTLD_NOW);
  98   if (p != NULL)
  99     FAIL_EXIT1 ("error: expected dlopen to fail because there is "
 100                 "not enough surplus static TLS.\n");
 101   printf ("...OK failed with: %s.\n", dlerror ());
 102
 103   xpthread_barrier_wait (&barrier);
 104   xpthread_join (blocked_thread);
 105
 106   /* Close the modules.  */
 107   for (int i = 0; i < 6; ++i)
 108     xdlclose (mods[i]);
 109
 110   return 0;
 111 }