hurd: Initialize TLS and libpthread before signal thread start

* sysdeps/generic/libc-start.h [!SHARED] (ARCH_SETUP_TLS): Define to
__libc_setup_tls.
* sysdeps/unix/sysv/linux/powerpc/libc-start.h [!SHARED]
(ARCH_SETUP_TLS): Likewise.
* sysdeps/mach/hurd/libc-start.h: New file copied from
sysdeps/generic/libc-start.h, but define ARCH_SETUP_TLS to empty.
* csu/libc-start.c [!SHARED] (LIBC_START_MAIN): Call ARCH_SETUP_TLS instead
of __libc_setup_tls.
* sysdeps/mach/hurd/i386/init-first.c [!SHARED] (init1): Call
__libc_setup_tls before initializing libpthread and running _hurd_init which
starts the signal thread.

csu/libc-start.c

@@ -194,7 +194,7 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
   ARCH_SETUP_IREL ();
 
   /* The stack guard goes into the TCB, so initialize it early.  */
-  __libc_setup_tls ();
+  ARCH_SETUP_TLS ();
 
   /* In some architectures, IREL{,A} relocations happen after TLS setup in
      order to let IFUNC resolvers benefit from TCB information, e.g. powerpc's

sysdeps/generic/libc-start.h

@@ -24,6 +24,7 @@
    initialization, and this means you cannot, without machine
    knowledge, access TLS from an IFUNC resolver.  */
 #define ARCH_SETUP_IREL() apply_irel ()
+#define ARCH_SETUP_TLS() __libc_setup_tls ()
 #define ARCH_APPLY_IREL()
 #endif /* ! SHARED  */
 

sysdeps/mach/hurd/i386/init-first.c

@@ -104,12 +104,12 @@ init1 (int argc, char *arg0, ...)
     ++envp;
   d = (void *) ++envp;
 
+#ifndef SHARED
   /* If we are the bootstrap task started by the kernel,
      then after the environment pointers there is no Hurd
      data block; the argument strings start there.  */
   if ((void *) d == argv[0] || d->phdr == 0)
     {
-#ifndef SHARED
       /* With a new enough linker (binutils-2.23 or better),
          the magic __ehdr_start symbol will be available and
          __libc_start_main will have done this that way already.  */
@@ -124,18 +124,27 @@ init1 (int argc, char *arg0, ...)
           _dl_phnum = ehdr->e_phnum;
           assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
         }
-#endif
-      return;
+    }
+  else
+    {
+      __libc_enable_secure = d->flags & EXEC_SECURE;
+
+      _dl_phdr = (ElfW(Phdr) *) d->phdr;
+      _dl_phnum = d->phdrsz / sizeof (ElfW(Phdr));
+      assert (d->phdrsz % sizeof (ElfW(Phdr)) == 0);
     }
 
-#ifndef SHARED
-  __libc_enable_secure = d->flags & EXEC_SECURE;
-
-  _dl_phdr = (ElfW(Phdr) *) d->phdr;
-  _dl_phnum = d->phdrsz / sizeof (ElfW(Phdr));
-  assert (d->phdrsz % sizeof (ElfW(Phdr)) == 0);
+  __libc_setup_tls ();
 #endif
 
+  /* Initialize libpthread if linked in.  */
+  if (__pthread_initialize_minimal != NULL)
+    __pthread_initialize_minimal ();
+
+  if ((void *) d == argv[0])
+    /* No Hurd data block to process.  */
+    return;
+
   _hurd_init_dtable = d->dtable;
   _hurd_init_dtablesize = d->dtablesize;
 

sysdeps/mach/hurd/libc-start.h

@@ -0,0 +1,31 @@
+/* Hurd definitions for libc main startup.
+   Copyright (C) 2017-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _LIBC_START_H
+#define _LIBC_START_H
+
+#ifndef SHARED
+/* By default we perform STT_GNU_IFUNC resolution *before* TLS
+   initialization, and this means you cannot, without machine
+   knowledge, access TLS from an IFUNC resolver.  */
+#define ARCH_SETUP_IREL() apply_irel ()
+#define ARCH_SETUP_TLS()
+#define ARCH_APPLY_IREL()
+#endif /* ! SHARED  */
+
+#endif /* _LIBC_START_H  */

sysdeps/unix/sysv/linux/powerpc/libc-start.h

@@ -23,6 +23,7 @@
 /* IREL{,A} must happen after TCB initialization in order to allow IFUNC
    resolvers to read TCB fields, e.g. hwcap and at_platform.  */
 #define ARCH_SETUP_IREL()
+#define ARCH_SETUP_TLS() __libc_setup_tls ()
 #define ARCH_APPLY_IREL() apply_irel ()
 #endif /* ! SHARED  */