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- /* Copyright (C) 2002-2007, 2009 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, see
- <http://www.gnu.org/licenses/>. */
- #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 <tls.h>
- #include <lowlevellock.h>
- #include <link.h>
- #include <bits/kernel-features.h>
- #ifndef NEED_SEPARATE_REGISTER_STACK
- /* Most architectures have exactly one stack pointer. Some have more. */
- # define STACK_VARIABLES void *stackaddr = NULL
- /* 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 = NULL; size_t stacksize = 0
- /* 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
- /* Newer kernels have the MAP_STACK flag to indicate a mapping is used for
- a stack. Use it when possible. */
- #ifndef MAP_STACK
- # define MAP_STACK 0
- #endif
- /* This yields the pointer that TLS support code calls the thread pointer. */
- #if defined(TLS_TCB_AT_TP)
- # define TLS_TPADJ(pd) (pd)
- #elif defined(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. GNU libc default is 40MiB
- embedded systems don't have enough ram for big dirty stack caches,
- reduce it to 16MiB. 4 does not work, f.e. tst-kill4 segfaults.
- */
- static size_t stack_cache_maxsize = 16 * 1024 * 1024;
- static size_t stack_cache_actsize;
- /* Mutex protecting this variable. */
- static int 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);
- /* We need to record what list operations we are going to do so that,
- in case of an asynchronous interruption due to a fork() call, we
- can correct for the work. */
- static uintptr_t in_flight_stack;
- /* 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 defined COLORING_INCREMENT && 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)
- static void
- stack_list_del (list_t *elem)
- {
- in_flight_stack = (uintptr_t) elem;
- atomic_write_barrier ();
- list_del (elem);
- atomic_write_barrier ();
- in_flight_stack = 0;
- }
- static void
- stack_list_add (list_t *elem, list_t *list)
- {
- in_flight_stack = (uintptr_t) elem | 1;
- atomic_write_barrier ();
- list_add (elem, list);
- atomic_write_barrier ();
- in_flight_stack = 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, LLL_PRIVATE);
- /* 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, LLL_PRIVATE);
- return NULL;
- }
- /* Dequeue the entry. */
- stack_list_del (&result->list);
- /* And add to the list of stacks in use. */
- stack_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, LLL_PRIVATE);
- /* 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;
- }
- /* Free stacks until cache size is lower than LIMIT. */
- void
- __free_stacks (size_t limit)
- {
- /* 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. */
- stack_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 <= limit)
- break;
- }
- }
- }
- /* 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. */
- stack_list_add (&stack->list, &stack_cache);
- stack_cache_actsize += stack->stackblock_size;
- if (__builtin_expect (stack_cache_actsize > stack_cache_maxsize, 0))
- __free_stacks (stack_cache_maxsize);
- }
- 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;
- #elif defined _STACK_GROWS_DOWN
- void *stack = pd->stackblock + pd->guardsize;
- size_t len = pd->stackblock_size - pd->guardsize;
- #elif defined _STACK_GROWS_UP
- void *stack = pd->stackblock;
- size_t len = (uintptr_t) pd - pd->guardsize - (uintptr_t) pd->stackblock;
- #else
- # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
- #endif
- #ifdef __ARCH_USE_MMU__
- if (mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0)
- return errno;
- #endif
- 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 defined(TLS_TCB_AT_TP)
- adj = ((uintptr_t) attr->stackaddr - TLS_TCB_SIZE)
- & __static_tls_align_m1;
- assert (size > adj + TLS_TCB_SIZE);
- #elif defined(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 defined(TLS_TCB_AT_TP)
- pd = (struct pthread *) ((uintptr_t) attr->stackaddr
- - TLS_TCB_SIZE - adj);
- #elif defined(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
- #ifndef __ASSUME_PRIVATE_FUTEX
- /* The thread must know when private futexes are supported. */
- pd->header.private_futex = THREAD_GETMEM (THREAD_SELF,
- header.private_futex);
- #endif
- #ifdef NEED_DL_SYSINFO
- /* Copy the sysinfo value from the parent. */
- THREAD_SYSINFO(pd) = THREAD_SELF_SYSINFO;
- #endif
- /* 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, LLL_PRIVATE);
- /* And add to the list of stacks in use. */
- list_add (&pd->list, &__stack_user);
- lll_unlock (stack_cache_lock, LLL_PRIVATE);
- }
- else
- {
- /* Allocate some anonymous memory. If possible use the cache. */
- size_t guardsize;
- size_t reqsize;
- void *mem = 0;
- const int prot = (PROT_READ | PROT_WRITE);
- #if defined COLORING_INCREMENT && 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)
- & ~pagesize_m1),
- 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 defined MULTI_PAGE_ALIASING && MULTI_PAGE_ALIASING != 0
- if ((size % MULTI_PAGE_ALIASING) == 0)
- size += pagesize_m1 + 1;
- #endif
- mem = mmap (NULL, size, prot,
- MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
- if (__builtin_expect (mem == MAP_FAILED, 0))
- {
- if (errno == ENOMEM)
- __set_errno (EAGAIN);
- 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 defined COLORING_INCREMENT && 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 defined(TLS_TCB_AT_TP)
- pd = (struct pthread *) ((char *) mem + size - coloring) - 1;
- #elif defined(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
- #ifndef __ASSUME_PRIVATE_FUTEX
- /* The thread must know when private futexes are supported. */
- pd->header.private_futex = THREAD_GETMEM (THREAD_SELF,
- header.private_futex);
- #endif
- #ifdef NEED_DL_SYSINFO
- /* Copy the sysinfo value from the parent. */
- THREAD_SYSINFO(pd) = THREAD_SELF_SYSINFO;
- #endif
- /* 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, LLL_PRIVATE);
- /* And add to the list of stacks in use. */
- stack_list_add (&pd->list, &stack_used);
- lll_unlock (stack_cache_lock, LLL_PRIVATE);
- /* 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);
- #elif defined _STACK_GROWS_DOWN
- char *guard = mem;
- #elif defined _STACK_GROWS_UP
- char *guard = (char *) (((uintptr_t) pd - guardsize) & ~pagesize_m1);
- #endif
- #ifdef __ARCH_USE_MMU__
- if (mprotect (guard, guardsize, PROT_NONE) != 0)
- {
- int err;
- #ifdef NEED_SEPARATE_REGISTER_STACK
- mprot_error:
- #endif
- err = errno;
- lll_lock (stack_cache_lock, LLL_PRIVATE);
- /* Remove the thread from the list. */
- stack_list_del (&pd->list);
- lll_unlock (stack_cache_lock, LLL_PRIVATE);
- /* 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;
- }
- #endif
- 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);
- #ifdef __ARCH_USE_MMU__
- 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;
- #elif defined _STACK_GROWS_DOWN
- if (mprotect ((char *) mem + guardsize, pd->guardsize - guardsize,
- prot) != 0)
- goto mprot_error;
- #elif defined _STACK_GROWS_UP
- if (mprotect ((char *) (((uintptr_t) pd - pd->guardsize) & ~pagesize_m1),
- pd->guardsize - guardsize, prot) != 0)
- goto mprot_error;
- #endif
- #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;
- /* The robust mutex lists also need to be initialized
- unconditionally because the cleanup for the previous stack owner
- might have happened in the kernel. */
- pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
- - offsetof (pthread_mutex_t,
- __data.__list.__next));
- pd->robust_head.list_op_pending = NULL;
- #ifdef __PTHREAD_MUTEX_HAVE_PREV
- pd->robust_prev = &pd->robust_head;
- #endif
- pd->robust_head.list = &pd->robust_head;
- /* We place the thread descriptor at the end of the stack. */
- *pdp = pd;
- #if defined(TLS_TCB_AT_TP)
- /* The stack begins before the TCB and the static TLS block. */
- stacktop = ((char *) (pd + 1) - __static_tls_size);
- #elif defined(TLS_DTV_AT_TP)
- stacktop = (char *) (pd - 1);
- #endif
- #ifdef NEED_SEPARATE_REGISTER_STACK
- *stack = pd->stackblock;
- *stacksize = stacktop - *stack;
- #elif defined _STACK_GROWS_DOWN
- *stack = stacktop;
- #elif defined _STACK_GROWS_UP
- *stack = pd->stackblock;
- assert (*stack > 0);
- #endif
- return 0;
- }
- void
- internal_function
- __deallocate_stack (struct pthread *pd)
- {
- lll_lock (stack_cache_lock, LLL_PRIVATE);
- /* Remove the thread from the list of threads with user defined
- stacks. */
- stack_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, LLL_PRIVATE);
- }
- int
- internal_function
- __make_stacks_executable (void **stack_endp)
- {
- /* First the main thread's stack. */
- int err = EPERM;
- if (err != 0)
- return err;
- #ifdef NEED_SEPARATE_REGISTER_STACK
- const size_t pagemask = ~(__getpagesize () - 1);
- #endif
- lll_lock (stack_cache_lock, LLL_PRIVATE);
- 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, LLL_PRIVATE);
- 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. But
- we have to be aware that we might have interrupted a list
- operation. */
- if (in_flight_stack != 0)
- {
- bool add_p = in_flight_stack & 1;
- list_t *elem = (list_t *)(uintptr_t)(in_flight_stack & ~UINTMAX_C (1));
- if (add_p)
- {
- /* We always add at the beginning of the list. So in this
- case we only need to check the beginning of these lists. */
- int check_list (list_t *l)
- {
- if (l->next->prev != l)
- {
- assert (l->next->prev == elem);
- elem->next = l->next;
- elem->prev = l;
- l->next = elem;
- return 1;
- }
- return 0;
- }
- if (check_list (&stack_used) == 0)
- (void) check_list (&stack_cache);
- }
- else
- {
- /* We can simply always replay the delete operation. */
- elem->next->prev = elem->prev;
- elem->prev->next = elem->next;
- }
- }
- /* Mark all stacks except the still running one as free. */
- list_t *runp;
- list_for_each (runp, &stack_used)
- {
- struct pthread *curp = list_entry (runp, struct pthread, list);
- if (curp != self)
- {
- /* This marks the stack as free. */
- curp->tid = 0;
- /* Account for the size of the stack. */
- stack_cache_actsize += curp->stackblock_size;
- if (curp->specific_used)
- {
- /* Clear the thread-specific data. */
- memset (curp->specific_1stblock, '\0',
- sizeof (curp->specific_1stblock));
- curp->specific_used = false;
- size_t cnt;
- for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
- if (curp->specific[cnt] != NULL)
- {
- memset (curp->specific[cnt], '\0',
- sizeof (curp->specific_1stblock));
- /* We have allocated the block which we do not
- free here so re-set the bit. */
- curp->specific_used = true;
- }
- }
- }
- }
- /* 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. */
- stack_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;
- in_flight_stack = 0;
- /* Initialize the lock. */
- stack_cache_lock = LLL_LOCK_INITIALIZER;
- }
- static void
- internal_function
- setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
- {
- int ch;
- /* Don't let the thread exit before the setxid handler runs. */
- t->setxid_futex = 0;
- do
- {
- ch = t->cancelhandling;
- /* If the thread is exiting right now, ignore it. */
- if ((ch & EXITING_BITMASK) != 0)
- return;
- }
- while (atomic_compare_and_exchange_bool_acq (&t->cancelhandling,
- ch | SETXID_BITMASK, ch));
- }
- static void
- internal_function
- setxid_unmark_thread (struct xid_command *cmdp, struct pthread *t)
- {
- int ch;
- do
- {
- ch = t->cancelhandling;
- if ((ch & SETXID_BITMASK) == 0)
- return;
- }
- while (atomic_compare_and_exchange_bool_acq (&t->cancelhandling,
- ch & ~SETXID_BITMASK, ch));
- /* Release the futex just in case. */
- t->setxid_futex = 1;
- lll_futex_wake (&t->setxid_futex, 1, LLL_PRIVATE);
- }
- static int
- internal_function
- setxid_signal_thread (struct xid_command *cmdp, struct pthread *t)
- {
- if ((t->cancelhandling & SETXID_BITMASK) == 0)
- return 0;
- int val;
- pid_t pid = getpid ();
- INTERNAL_SYSCALL_DECL (err);
- val = INTERNAL_SYSCALL (tgkill, err, 3, pid, t->tid, SIGSETXID);
- /* If this failed, it must have had not started yet or else exited. */
- if (!INTERNAL_SYSCALL_ERROR_P (val, err))
- {
- atomic_increment (&cmdp->cntr);
- return 1;
- }
- else
- return 0;
- }
- int
- attribute_hidden
- __nptl_setxid (struct xid_command *cmdp)
- {
- int signalled;
- int result;
- lll_lock (stack_cache_lock, LLL_PRIVATE);
- __xidcmd = cmdp;
- cmdp->cntr = 0;
- 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)
- continue;
- setxid_mark_thread (cmdp, t);
- }
- /* 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)
- continue;
- setxid_mark_thread (cmdp, t);
- }
- /* Iterate until we don't succeed in signalling anyone. That means
- we have gotten all running threads, and their children will be
- automatically correct once started. */
- do
- {
- signalled = 0;
- list_for_each (runp, &stack_used)
- {
- struct pthread *t = list_entry (runp, struct pthread, list);
- if (t == self)
- continue;
- signalled += setxid_signal_thread (cmdp, t);
- }
- list_for_each (runp, &__stack_user)
- {
- struct pthread *t = list_entry (runp, struct pthread, list);
- if (t == self)
- continue;
- signalled += setxid_signal_thread (cmdp, t);
- }
- int cur = cmdp->cntr;
- while (cur != 0)
- {
- lll_futex_wait (&cmdp->cntr, cur, LLL_PRIVATE);
- cur = cmdp->cntr;
- }
- }
- while (signalled != 0);
- /* Clean up flags, so that no thread blocks during exit waiting
- for a signal which will never come. */
- list_for_each (runp, &stack_used)
- {
- struct pthread *t = list_entry (runp, struct pthread, list);
- if (t == self)
- continue;
- setxid_unmark_thread (cmdp, t);
- }
- list_for_each (runp, &__stack_user)
- {
- struct pthread *t = list_entry (runp, struct pthread, list);
- if (t == self)
- continue;
- setxid_unmark_thread (cmdp, t);
- }
- /* This must be last, otherwise the current thread might not have
- permissions to send SIGSETXID syscall to the other threads. */
- INTERNAL_SYSCALL_DECL (err);
- 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, LLL_PRIVATE);
- 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 defined(TLS_TCB_AT_TP)
- void *dest = (char *) curp - map->l_tls_offset;
- # elif defined(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, LLL_PRIVATE);
- /* 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, LLL_PRIVATE);
- }
- void
- attribute_hidden
- __wait_lookup_done (void)
- {
- lll_lock (stack_cache_lock, LLL_PRIVATE);
- 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 || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
- continue;
- int *const gscope_flagp = &t->header.gscope_flag;
- /* We have to wait until this thread is done with the global
- scope. First tell the thread that we are waiting and
- possibly have to be woken. */
- if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
- THREAD_GSCOPE_FLAG_WAIT,
- THREAD_GSCOPE_FLAG_USED))
- continue;
- do
- lll_futex_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
- while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
- }
- /* 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 || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
- continue;
- int *const gscope_flagp = &t->header.gscope_flag;
- /* We have to wait until this thread is done with the global
- scope. First tell the thread that we are waiting and
- possibly have to be woken. */
- if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
- THREAD_GSCOPE_FLAG_WAIT,
- THREAD_GSCOPE_FLAG_USED))
- continue;
- do
- lll_futex_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
- while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
- }
- lll_unlock (stack_cache_lock, LLL_PRIVATE);
- }
|