Import in NPTL code from glibc. For further information please

consult the 'README.NPTL' file.

1 files changed, 947 insertions, 0 deletions

diff --git a/libpthread/nptl/allocatestack.c b/libpthread/nptl/allocatestack.c
new file mode 100644
index 000000000..fcb6c6e47
--- /dev/null
+++ b/libpthread/nptl/allocatestack.c
@@ -0,0 +1,947 @@
+/* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <dl-sysdep.h>
+#include <tls.h>
+#include <lowlevellock.h>
+
+
+#ifndef NEED_SEPARATE_REGISTER_STACK
+
+/* Most architectures have exactly one stack pointer.  Some have more.  */
+# define STACK_VARIABLES void *stackaddr
+
+/* How to pass the values to the 'create_thread' function.  */
+# define STACK_VARIABLES_ARGS stackaddr
+
+/* How to declare function which gets there parameters.  */
+# define STACK_VARIABLES_PARMS void *stackaddr
+
+/* How to declare allocate_stack.  */
+# define ALLOCATE_STACK_PARMS void **stack
+
+/* This is how the function is called.  We do it this way to allow
+   other variants of the function to have more parameters.  */
+# define ALLOCATE_STACK(attr, pd) allocate_stack (attr, pd, &stackaddr)
+
+#else
+
+/* We need two stacks.  The kernel will place them but we have to tell
+   the kernel about the size of the reserved address space.  */
+# define STACK_VARIABLES void *stackaddr; size_t stacksize
+
+/* How to pass the values to the 'create_thread' function.  */
+# define STACK_VARIABLES_ARGS stackaddr, stacksize
+
+/* How to declare function which gets there parameters.  */
+# define STACK_VARIABLES_PARMS void *stackaddr, size_t stacksize
+
+/* How to declare allocate_stack.  */
+# define ALLOCATE_STACK_PARMS void **stack, size_t *stacksize
+
+/* This is how the function is called.  We do it this way to allow
+   other variants of the function to have more parameters.  */
+# define ALLOCATE_STACK(attr, pd) \
+  allocate_stack (attr, pd, &stackaddr, &stacksize)
+
+#endif
+
+
+/* Default alignment of stack.  */
+#ifndef STACK_ALIGN
+# define STACK_ALIGN __alignof__ (long double)
+#endif
+
+/* Default value for minimal stack size after allocating thread
+   descriptor and guard.  */
+#ifndef MINIMAL_REST_STACK
+# define MINIMAL_REST_STACK	4096
+#endif
+
+
+/* Let the architecture add some flags to the mmap() call used to
+   allocate stacks.  */
+#ifndef ARCH_MAP_FLAGS
+# define ARCH_MAP_FLAGS 0
+#endif
+
+/* This yields the pointer that TLS support code calls the thread pointer.  */
+#if TLS_TCB_AT_TP
+# define TLS_TPADJ(pd) (pd)
+#elif TLS_DTV_AT_TP
+# define TLS_TPADJ(pd) ((struct pthread *)((char *) (pd) + TLS_PRE_TCB_SIZE))
+#endif
+
+/* Cache handling for not-yet free stacks.  */
+
+/* Maximum size in kB of cache.  */
+static size_t stack_cache_maxsize = 40 * 1024 * 1024; /* 40MiBi by default.  */
+static size_t stack_cache_actsize;
+
+/* Mutex protecting this variable.  */
+static lll_lock_t stack_cache_lock = LLL_LOCK_INITIALIZER;
+
+/* List of queued stack frames.  */
+static LIST_HEAD (stack_cache);
+
+/* List of the stacks in use.  */
+static LIST_HEAD (stack_used);
+
+/* List of the threads with user provided stacks in use.  No need to
+   initialize this, since it's done in __pthread_initialize_minimal.  */
+list_t __stack_user __attribute__ ((nocommon));
+hidden_data_def (__stack_user)
+
+#if COLORING_INCREMENT != 0
+/* Number of threads created.  */
+static unsigned int nptl_ncreated;
+#endif
+
+
+/* Check whether the stack is still used or not.  */
+#define FREE_P(descr) ((descr)->tid <= 0)
+
+
+/* We create a double linked list of all cache entries.  Double linked
+   because this allows removing entries from the end.  */
+
+
+/* Get a stack frame from the cache.  We have to match by size since
+   some blocks might be too small or far too large.  */
+static struct pthread *
+get_cached_stack (size_t *sizep, void **memp)
+{
+  size_t size = *sizep;
+  struct pthread *result = NULL;
+  list_t *entry;
+
+  lll_lock (stack_cache_lock);
+
+  /* Search the cache for a matching entry.  We search for the
+     smallest stack which has at least the required size.  Note that
+     in normal situations the size of all allocated stacks is the
+     same.  As the very least there are only a few different sizes.
+     Therefore this loop will exit early most of the time with an
+     exact match.  */
+  list_for_each (entry, &stack_cache)
+    {
+      struct pthread *curr;
+
+      curr = list_entry (entry, struct pthread, list);
+      if (FREE_P (curr) && curr->stackblock_size >= size)
+	{
+	  if (curr->stackblock_size == size)
+	    {
+	      result = curr;
+	      break;
+	    }
+
+	  if (result == NULL
+	      || result->stackblock_size > curr->stackblock_size)
+	    result = curr;
+	}
+    }
+
+  if (__builtin_expect (result == NULL, 0)
+      /* Make sure the size difference is not too excessive.  In that
+	 case we do not use the block.  */
+      || __builtin_expect (result->stackblock_size > 4 * size, 0))
+    {
+      /* Release the lock.  */
+      lll_unlock (stack_cache_lock);
+
+      return NULL;
+    }
+
+  /* Dequeue the entry.  */
+  list_del (&result->list);
+
+  /* And add to the list of stacks in use.  */
+  list_add (&result->list, &stack_used);
+
+  /* And decrease the cache size.  */
+  stack_cache_actsize -= result->stackblock_size;
+
+  /* Release the lock early.  */
+  lll_unlock (stack_cache_lock);
+
+  /* Report size and location of the stack to the caller.  */
+  *sizep = result->stackblock_size;
+  *memp = result->stackblock;
+
+  /* Cancellation handling is back to the default.  */
+  result->cancelhandling = 0;
+  result->cleanup = NULL;
+
+  /* No pending event.  */
+  result->nextevent = NULL;
+
+  /* Clear the DTV.  */
+  dtv_t *dtv = GET_DTV (TLS_TPADJ (result));
+  memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t));
+
+  /* Re-initialize the TLS.  */
+  _dl_allocate_tls_init (TLS_TPADJ (result));
+
+  return result;
+}
+
+
+/* Add a stack frame which is not used anymore to the stack.  Must be
+   called with the cache lock held.  */
+static inline void
+__attribute ((always_inline))
+queue_stack (struct pthread *stack)
+{
+  /* We unconditionally add the stack to the list.  The memory may
+     still be in use but it will not be reused until the kernel marks
+     the stack as not used anymore.  */
+  list_add (&stack->list, &stack_cache);
+
+  stack_cache_actsize += stack->stackblock_size;
+  if (__builtin_expect (stack_cache_actsize > stack_cache_maxsize, 0))
+    {
+      /* We reduce the size of the cache.  Remove the last entries
+	 until the size is below the limit.  */
+      list_t *entry;
+      list_t *prev;
+
+      /* Search from the end of the list.  */
+      list_for_each_prev_safe (entry, prev, &stack_cache)
+	{
+	  struct pthread *curr;
+
+	  curr = list_entry (entry, struct pthread, list);
+	  if (FREE_P (curr))
+	    {
+	      /* Unlink the block.  */
+	      list_del (entry);
+
+	      /* Account for the freed memory.  */
+	      stack_cache_actsize -= curr->stackblock_size;
+
+	      /* Free the memory associated with the ELF TLS.  */
+	      _dl_deallocate_tls (TLS_TPADJ (curr), false);
+
+	      /* Remove this block.  This should never fail.  If it
+		 does something is really wrong.  */
+	      if (munmap (curr->stackblock, curr->stackblock_size) != 0)
+		abort ();
+
+	      /* Maybe we have freed enough.  */
+	      if (stack_cache_actsize <= stack_cache_maxsize)
+		break;
+	    }
+	}
+    }
+}
+
+
+static int
+internal_function
+change_stack_perm (struct pthread *pd
+#ifdef NEED_SEPARATE_REGISTER_STACK
+		   , size_t pagemask
+#endif
+		   )
+{
+#ifdef NEED_SEPARATE_REGISTER_STACK
+  void *stack = (pd->stackblock
+		 + (((((pd->stackblock_size - pd->guardsize) / 2)
+		      & pagemask) + pd->guardsize) & pagemask));
+  size_t len = pd->stackblock + pd->stackblock_size - stack;
+#else
+  void *stack = pd->stackblock + pd->guardsize;
+  size_t len = pd->stackblock_size - pd->guardsize;
+#endif
+  if (mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0)
+    return errno;
+
+  return 0;
+}
+
+
+static int
+allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
+		ALLOCATE_STACK_PARMS)
+{
+  struct pthread *pd;
+  size_t size;
+  size_t pagesize_m1 = __getpagesize () - 1;
+  void *stacktop;
+
+  assert (attr != NULL);
+  assert (powerof2 (pagesize_m1 + 1));
+  assert (TCB_ALIGNMENT >= STACK_ALIGN);
+
+  /* Get the stack size from the attribute if it is set.  Otherwise we
+     use the default we determined at start time.  */
+  size = attr->stacksize ?: __default_stacksize;
+
+  /* Get memory for the stack.  */
+  if (__builtin_expect (attr->flags & ATTR_FLAG_STACKADDR, 0))
+    {
+      uintptr_t adj;
+
+      /* If the user also specified the size of the stack make sure it
+	 is large enough.  */
+      if (attr->stacksize != 0
+	  && attr->stacksize < (__static_tls_size + MINIMAL_REST_STACK))
+	return EINVAL;
+
+      /* Adjust stack size for alignment of the TLS block.  */
+#if TLS_TCB_AT_TP
+      adj = ((uintptr_t) attr->stackaddr - TLS_TCB_SIZE)
+	    & __static_tls_align_m1;
+      assert (size > adj + TLS_TCB_SIZE);
+#elif TLS_DTV_AT_TP
+      adj = ((uintptr_t) attr->stackaddr - __static_tls_size)
+	    & __static_tls_align_m1;
+      assert (size > adj);
+#endif
+
+      /* The user provided some memory.  Let's hope it matches the
+	 size...  We do not allocate guard pages if the user provided
+	 the stack.  It is the user's responsibility to do this if it
+	 is wanted.  */
+#if TLS_TCB_AT_TP
+      pd = (struct pthread *) ((uintptr_t) attr->stackaddr
+			       - TLS_TCB_SIZE - adj);
+#elif TLS_DTV_AT_TP
+      pd = (struct pthread *) (((uintptr_t) attr->stackaddr
+			        - __static_tls_size - adj)
+			       - TLS_PRE_TCB_SIZE);
+#endif
+
+      /* The user provided stack memory needs to be cleared.  */
+      memset (pd, '\0', sizeof (struct pthread));
+
+      /* The first TSD block is included in the TCB.  */
+      pd->specific[0] = pd->specific_1stblock;
+
+      /* Remember the stack-related values.  */
+      pd->stackblock = (char *) attr->stackaddr - size;
+      pd->stackblock_size = size;
+
+      /* This is a user-provided stack.  It will not be queued in the
+	 stack cache nor will the memory (except the TLS memory) be freed.  */
+      pd->user_stack = true;
+
+      /* This is at least the second thread.  */
+      pd->header.multiple_threads = 1;
+#ifndef TLS_MULTIPLE_THREADS_IN_TCB
+      __pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
+#endif
+
+#ifdef NEED_DL_SYSINFO
+      /* Copy the sysinfo value from the parent.  */
+      THREAD_SYSINFO(pd) = THREAD_SELF_SYSINFO;
+#endif
+
+      /* The process ID is also the same as that of the caller.  */
+      pd->pid = THREAD_GETMEM (THREAD_SELF, pid);
+
+      /* Allocate the DTV for this thread.  */
+      if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL)
+	{
+	  /* Something went wrong.  */
+	  assert (errno == ENOMEM);
+	  return EAGAIN;
+	}
+
+
+      /* Prepare to modify global data.  */
+      lll_lock (stack_cache_lock);
+
+      /* And add to the list of stacks in use.  */
+      list_add (&pd->list, &__stack_user);
+
+      lll_unlock (stack_cache_lock);
+    }
+  else
+    {
+      /* Allocate some anonymous memory.  If possible use the cache.  */
+      size_t guardsize;
+      size_t reqsize;
+      void *mem;
+      const int prot = (PROT_READ | PROT_WRITE
+			| ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
+
+#if COLORING_INCREMENT != 0
+      /* Add one more page for stack coloring.  Don't do it for stacks
+	 with 16 times pagesize or larger.  This might just cause
+	 unnecessary misalignment.  */
+      if (size <= 16 * pagesize_m1)
+	size += pagesize_m1 + 1;
+#endif
+
+      /* Adjust the stack size for alignment.  */
+      size &= ~__static_tls_align_m1;
+      assert (size != 0);
+
+      /* Make sure the size of the stack is enough for the guard and
+	 eventually the thread descriptor.  */
+      guardsize = (attr->guardsize + pagesize_m1) & ~pagesize_m1;
+      if (__builtin_expect (size < (guardsize + __static_tls_size
+				    + MINIMAL_REST_STACK + pagesize_m1 + 1),
+			    0))
+	/* The stack is too small (or the guard too large).  */
+	return EINVAL;
+
+      /* Try to get a stack from the cache.  */
+      reqsize = size;
+      pd = get_cached_stack (&size, &mem);
+      if (pd == NULL)
+	{
+	  /* To avoid aliasing effects on a larger scale than pages we
+	     adjust the allocated stack size if necessary.  This way
+	     allocations directly following each other will not have
+	     aliasing problems.  */
+#if MULTI_PAGE_ALIASING != 0
+	  if ((size % MULTI_PAGE_ALIASING) == 0)
+	    size += pagesize_m1 + 1;
+#endif
+
+	  mem = mmap (NULL, size, prot,
+		      MAP_PRIVATE | MAP_ANONYMOUS | ARCH_MAP_FLAGS, -1, 0);
+
+	  if (__builtin_expect (mem == MAP_FAILED, 0))
+	    {
+#ifdef ARCH_RETRY_MMAP
+	      mem = ARCH_RETRY_MMAP (size);
+	      if (__builtin_expect (mem == MAP_FAILED, 0))
+#endif
+		return errno;
+	    }
+
+	  /* SIZE is guaranteed to be greater than zero.
+	     So we can never get a null pointer back from mmap.  */
+	  assert (mem != NULL);
+
+#if COLORING_INCREMENT != 0
+	  /* Atomically increment NCREATED.  */
+	  unsigned int ncreated = atomic_increment_val (&nptl_ncreated);
+
+	  /* We chose the offset for coloring by incrementing it for
+	     every new thread by a fixed amount.  The offset used
+	     module the page size.  Even if coloring would be better
+	     relative to higher alignment values it makes no sense to
+	     do it since the mmap() interface does not allow us to
+	     specify any alignment for the returned memory block.  */
+	  size_t coloring = (ncreated * COLORING_INCREMENT) & pagesize_m1;
+
+	  /* Make sure the coloring offsets does not disturb the alignment
+	     of the TCB and static TLS block.  */
+	  if (__builtin_expect ((coloring & __static_tls_align_m1) != 0, 0))
+	    coloring = (((coloring + __static_tls_align_m1)
+			 & ~(__static_tls_align_m1))
+			& ~pagesize_m1);
+#else
+	  /* Unless specified we do not make any adjustments.  */
+# define coloring 0
+#endif
+
+	  /* Place the thread descriptor at the end of the stack.  */
+#if TLS_TCB_AT_TP
+	  pd = (struct pthread *) ((char *) mem + size - coloring) - 1;
+#elif TLS_DTV_AT_TP
+	  pd = (struct pthread *) ((((uintptr_t) mem + size - coloring
+				    - __static_tls_size)
+				    & ~__static_tls_align_m1)
+				   - TLS_PRE_TCB_SIZE);
+#endif
+
+	  /* Remember the stack-related values.  */
+	  pd->stackblock = mem;
+	  pd->stackblock_size = size;
+
+	  /* We allocated the first block thread-specific data array.
+	     This address will not change for the lifetime of this
+	     descriptor.  */
+	  pd->specific[0] = pd->specific_1stblock;
+
+	  /* This is at least the second thread.  */
+	  pd->header.multiple_threads = 1;
+#ifndef TLS_MULTIPLE_THREADS_IN_TCB
+	  __pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
+#endif
+
+#ifdef NEED_DL_SYSINFO
+	  /* Copy the sysinfo value from the parent.  */
+	  THREAD_SYSINFO(pd) = THREAD_SELF_SYSINFO;
+#endif
+
+	  /* The process ID is also the same as that of the caller.  */
+	  pd->pid = THREAD_GETMEM (THREAD_SELF, pid);
+
+	  /* Allocate the DTV for this thread.  */
+	  if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL)
+	    {
+	      /* Something went wrong.  */
+	      assert (errno == ENOMEM);
+
+	      /* Free the stack memory we just allocated.  */
+	      (void) munmap (mem, size);
+
+	      return EAGAIN;
+	    }
+
+
+	  /* Prepare to modify global data.  */
+	  lll_lock (stack_cache_lock);
+
+	  /* And add to the list of stacks in use.  */
+	  list_add (&pd->list, &stack_used);
+
+	  lll_unlock (stack_cache_lock);
+
+
+	  /* There might have been a race.  Another thread might have
+	     caused the stacks to get exec permission while this new
+	     stack was prepared.  Detect if this was possible and
+	     change the permission if necessary.  */
+	  if (__builtin_expect ((GL(dl_stack_flags) & PF_X) != 0
+				&& (prot & PROT_EXEC) == 0, 0))
+	    {
+	      int err = change_stack_perm (pd
+#ifdef NEED_SEPARATE_REGISTER_STACK
+					   , ~pagesize_m1
+#endif
+					   );
+	      if (err != 0)
+		{
+		  /* Free the stack memory we just allocated.  */
+		  (void) munmap (mem, size);
+
+		  return err;
+		}
+	    }
+
+
+	  /* Note that all of the stack and the thread descriptor is
+	     zeroed.  This means we do not have to initialize fields
+	     with initial value zero.  This is specifically true for
+	     the 'tid' field which is always set back to zero once the
+	     stack is not used anymore and for the 'guardsize' field
+	     which will be read next.  */
+	}
+
+      /* Create or resize the guard area if necessary.  */
+      if (__builtin_expect (guardsize > pd->guardsize, 0))
+	{
+#ifdef NEED_SEPARATE_REGISTER_STACK
+	  char *guard = mem + (((size - guardsize) / 2) & ~pagesize_m1);
+#else
+	  char *guard = mem;
+#endif
+	  if (mprotect (guard, guardsize, PROT_NONE) != 0)
+	    {
+	      int err;
+	    mprot_error:
+	      err = errno;
+
+	      lll_lock (stack_cache_lock);
+
+	      /* Remove the thread from the list.  */
+	      list_del (&pd->list);
+
+	      lll_unlock (stack_cache_lock);
+
+	      /* Get rid of the TLS block we allocated.  */
+	      _dl_deallocate_tls (TLS_TPADJ (pd), false);
+
+	      /* Free the stack memory regardless of whether the size
+		 of the cache is over the limit or not.  If this piece
+		 of memory caused problems we better do not use it
+		 anymore.  Uh, and we ignore possible errors.  There
+		 is nothing we could do.  */
+	      (void) munmap (mem, size);
+
+	      return err;
+	    }
+
+	  pd->guardsize = guardsize;
+	}
+      else if (__builtin_expect (pd->guardsize - guardsize > size - reqsize,
+				 0))
+	{
+	  /* The old guard area is too large.  */
+
+#ifdef NEED_SEPARATE_REGISTER_STACK
+	  char *guard = mem + (((size - guardsize) / 2) & ~pagesize_m1);
+	  char *oldguard = mem + (((size - pd->guardsize) / 2) & ~pagesize_m1);
+
+	  if (oldguard < guard
+	      && mprotect (oldguard, guard - oldguard, prot) != 0)
+	    goto mprot_error;
+
+	  if (mprotect (guard + guardsize,
+			oldguard + pd->guardsize - guard - guardsize,
+			prot) != 0)
+	    goto mprot_error;
+#else
+	  if (mprotect ((char *) mem + guardsize, pd->guardsize - guardsize,
+			prot) != 0)
+	    goto mprot_error;
+#endif
+
+	  pd->guardsize = guardsize;
+	}
+      /* The pthread_getattr_np() calls need to get passed the size
+	 requested in the attribute, regardless of how large the
+	 actually used guardsize is.  */
+      pd->reported_guardsize = guardsize;
+    }
+
+  /* Initialize the lock.  We have to do this unconditionally since the
+     stillborn thread could be canceled while the lock is taken.  */
+  pd->lock = LLL_LOCK_INITIALIZER;
+
+  /* We place the thread descriptor at the end of the stack.  */
+  *pdp = pd;
+
+#if TLS_TCB_AT_TP
+  /* The stack begins before the TCB and the static TLS block.  */
+  stacktop = ((char *) (pd + 1) - __static_tls_size);
+#elif TLS_DTV_AT_TP
+  stacktop = (char *) (pd - 1);
+#endif
+
+#ifdef NEED_SEPARATE_REGISTER_STACK
+  *stack = pd->stackblock;
+  *stacksize = stacktop - *stack;
+#else
+  *stack = stacktop;
+#endif
+
+  return 0;
+}
+
+
+void
+internal_function
+__deallocate_stack (struct pthread *pd)
+{
+  lll_lock (stack_cache_lock);
+
+  /* Remove the thread from the list of threads with user defined
+     stacks.  */
+  list_del (&pd->list);
+
+  /* Not much to do.  Just free the mmap()ed memory.  Note that we do
+     not reset the 'used' flag in the 'tid' field.  This is done by
+     the kernel.  If no thread has been created yet this field is
+     still zero.  */
+  if (__builtin_expect (! pd->user_stack, 1))
+    (void) queue_stack (pd);
+  else
+    /* Free the memory associated with the ELF TLS.  */
+    _dl_deallocate_tls (TLS_TPADJ (pd), false);
+
+  lll_unlock (stack_cache_lock);
+}
+
+
+int
+internal_function
+__make_stacks_executable (void **stack_endp)
+{
+  /* First the main thread's stack.  */
+  int err = _dl_make_stack_executable (stack_endp);
+  if (err != 0)
+    return err;
+
+#ifdef NEED_SEPARATE_REGISTER_STACK
+  const size_t pagemask = ~(__getpagesize () - 1);
+#endif
+
+  lll_lock (stack_cache_lock);
+
+  list_t *runp;
+  list_for_each (runp, &stack_used)
+    {
+      err = change_stack_perm (list_entry (runp, struct pthread, list)
+#ifdef NEED_SEPARATE_REGISTER_STACK
+			       , pagemask
+#endif
+			       );
+      if (err != 0)
+	break;
+    }
+
+  /* Also change the permission for the currently unused stacks.  This
+     might be wasted time but better spend it here than adding a check
+     in the fast path.  */
+  if (err == 0)
+    list_for_each (runp, &stack_cache)
+      {
+	err = change_stack_perm (list_entry (runp, struct pthread, list)
+#ifdef NEED_SEPARATE_REGISTER_STACK
+				 , pagemask
+#endif
+				 );
+	if (err != 0)
+	  break;
+      }
+
+  lll_unlock (stack_cache_lock);
+
+  return err;
+}
+
+
+/* In case of a fork() call the memory allocation in the child will be
+   the same but only one thread is running.  All stacks except that of
+   the one running thread are not used anymore.  We have to recycle
+   them.  */
+void
+__reclaim_stacks (void)
+{
+  struct pthread *self = (struct pthread *) THREAD_SELF;
+
+  /* No locking necessary.  The caller is the only stack in use.  */
+
+  /* Mark all stacks except the still running one as free.  */
+  list_t *runp;
+  list_for_each (runp, &stack_used)
+    {
+      struct pthread *curp;
+
+      curp = list_entry (runp, struct pthread, list);
+      if (curp != self)
+	{
+	  /* This marks the stack as free.  */
+	  curp->tid = 0;
+
+	  /* The PID field must be initialized for the new process.  */
+	  curp->pid = self->pid;
+
+	  /* Account for the size of the stack.  */
+	  stack_cache_actsize += curp->stackblock_size;
+	}
+    }
+
+  /* Add the stack of all running threads to the cache.  */
+  list_splice (&stack_used, &stack_cache);
+
+  /* Remove the entry for the current thread to from the cache list
+     and add it to the list of running threads.  Which of the two
+     lists is decided by the user_stack flag.  */
+  list_del (&self->list);
+
+  /* Re-initialize the lists for all the threads.  */
+  INIT_LIST_HEAD (&stack_used);
+  INIT_LIST_HEAD (&__stack_user);
+
+  if (__builtin_expect (THREAD_GETMEM (self, user_stack), 0))
+    list_add (&self->list, &__stack_user);
+  else
+    list_add (&self->list, &stack_used);
+
+  /* There is one thread running.  */
+  __nptl_nthreads = 1;
+
+  /* Initialize the lock.  */
+  stack_cache_lock = LLL_LOCK_INITIALIZER;
+}
+
+
+#if HP_TIMING_AVAIL
+# undef __find_thread_by_id
+/* Find a thread given the thread ID.  */
+attribute_hidden
+struct pthread *
+__find_thread_by_id (pid_t tid)
+{
+  struct pthread *result = NULL;
+
+  lll_lock (stack_cache_lock);
+
+  /* Iterate over the list with system-allocated threads first.  */
+  list_t *runp;
+  list_for_each (runp, &stack_used)
+    {
+      struct pthread *curp;
+
+      curp = list_entry (runp, struct pthread, list);
+
+      if (curp->tid == tid)
+	{
+	  result = curp;
+	  goto out;
+	}
+    }
+
+  /* Now the list with threads using user-allocated stacks.  */
+  list_for_each (runp, &__stack_user)
+    {
+      struct pthread *curp;
+
+      curp = list_entry (runp, struct pthread, list);
+
+      if (curp->tid == tid)
+	{
+	  result = curp;
+	  goto out;
+	}
+    }
+
+ out:
+  lll_unlock (stack_cache_lock);
+
+  return result;
+}
+#endif
+
+int
+attribute_hidden
+__nptl_setxid (struct xid_command *cmdp)
+{
+  int result;
+  lll_lock (stack_cache_lock);
+
+  __xidcmd = cmdp;
+  cmdp->cntr = 0;
+
+  INTERNAL_SYSCALL_DECL (err);
+
+  struct pthread *self = THREAD_SELF;
+
+  /* Iterate over the list with system-allocated threads first.  */
+  list_t *runp;
+  list_for_each (runp, &stack_used)
+    {
+      struct pthread *t = list_entry (runp, struct pthread, list);
+      if (t != self)
+	{
+	  int val;
+#if __ASSUME_TGKILL
+	  val = INTERNAL_SYSCALL (tgkill, err, 3,
+				  THREAD_GETMEM (THREAD_SELF, pid),
+				  t->tid, SIGSETXID);
+#else
+# ifdef __NR_tgkill
+	  val = INTERNAL_SYSCALL (tgkill, err, 3,
+				  THREAD_GETMEM (THREAD_SELF, pid),
+				  t->tid, SIGSETXID);
+	  if (INTERNAL_SYSCALL_ERROR_P (val, err)
+	      && INTERNAL_SYSCALL_ERRNO (val, err) == ENOSYS)
+# endif
+	    val = INTERNAL_SYSCALL (tkill, err, 2, t->tid, SIGSETXID);
+#endif
+
+	  if (!INTERNAL_SYSCALL_ERROR_P (val, err))
+	    atomic_increment (&cmdp->cntr);
+	}
+    }
+
+  /* Now the list with threads using user-allocated stacks.  */
+  list_for_each (runp, &__stack_user)
+    {
+      struct pthread *t = list_entry (runp, struct pthread, list);
+      if (t != self)
+	{
+	  int val;
+#if __ASSUME_TGKILL
+	  val = INTERNAL_SYSCALL (tgkill, err, 3,
+				  THREAD_GETMEM (THREAD_SELF, pid),
+				  t->tid, SIGSETXID);
+#else
+# ifdef __NR_tgkill
+	  val = INTERNAL_SYSCALL (tgkill, err, 3,
+				  THREAD_GETMEM (THREAD_SELF, pid),
+				  t->tid, SIGSETXID);
+	  if (INTERNAL_SYSCALL_ERROR_P (val, err)
+	      && INTERNAL_SYSCALL_ERRNO (val, err) == ENOSYS)
+# endif
+	    val = INTERNAL_SYSCALL (tkill, err, 2, t->tid, SIGSETXID);
+#endif
+
+	  if (!INTERNAL_SYSCALL_ERROR_P (val, err))
+	    atomic_increment (&cmdp->cntr);
+	}
+    }
+
+  int cur = cmdp->cntr;
+  while (cur != 0)
+    {
+      lll_futex_wait (&cmdp->cntr, cur);
+      cur = cmdp->cntr;
+    }
+
+  /* This must be last, otherwise the current thread might not have
+     permissions to send SIGSETXID syscall to the other threads.  */
+  result = INTERNAL_SYSCALL_NCS (cmdp->syscall_no, err, 3,
+				 cmdp->id[0], cmdp->id[1], cmdp->id[2]);
+  if (INTERNAL_SYSCALL_ERROR_P (result, err))
+    {
+      __set_errno (INTERNAL_SYSCALL_ERRNO (result, err));
+      result = -1;
+    }
+
+  lll_unlock (stack_cache_lock);
+  return result;
+}
+
+static inline void __attribute__((always_inline))
+init_one_static_tls (struct pthread *curp, struct link_map *map)
+{
+  dtv_t *dtv = GET_DTV (TLS_TPADJ (curp));
+# if TLS_TCB_AT_TP
+  void *dest = (char *) curp - map->l_tls_offset;
+# elif TLS_DTV_AT_TP
+  void *dest = (char *) curp + map->l_tls_offset + TLS_PRE_TCB_SIZE;
+# else
+#  error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+# endif
+
+  /* Fill in the DTV slot so that a later LD/GD access will find it.  */
+  dtv[map->l_tls_modid].pointer.val = dest;
+  dtv[map->l_tls_modid].pointer.is_static = true;
+
+  /* Initialize the memory.  */
+  memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
+	  '\0', map->l_tls_blocksize - map->l_tls_initimage_size);
+}
+
+void
+attribute_hidden
+__pthread_init_static_tls (struct link_map *map)
+{
+  lll_lock (stack_cache_lock);
+
+  /* Iterate over the list with system-allocated threads first.  */
+  list_t *runp;
+  list_for_each (runp, &stack_used)
+    init_one_static_tls (list_entry (runp, struct pthread, list), map);
+
+  /* Now the list with threads using user-allocated stacks.  */
+  list_for_each (runp, &__stack_user)
+    init_one_static_tls (list_entry (runp, struct pthread, list), map);
+
+  lll_unlock (stack_cache_lock);
+}