diff options
Diffstat (limited to 'REORG.TODO/nptl/allocatestack.c')
| -rw-r--r-- | REORG.TODO/nptl/allocatestack.c | 1238 |
1 files changed, 1238 insertions, 0 deletions
diff --git a/REORG.TODO/nptl/allocatestack.c b/REORG.TODO/nptl/allocatestack.c new file mode 100644 index 0000000000..e5c5f79a82 --- /dev/null +++ b/REORG.TODO/nptl/allocatestack.c @@ -0,0 +1,1238 @@ +/* Copyright (C) 2002-2017 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 <dl-sysdep.h> +#include <dl-tls.h> +#include <tls.h> +#include <list.h> +#include <lowlevellock.h> +#include <futex-internal.h> +#include <kernel-features.h> +#include <stack-aliasing.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 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 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) + + +/* 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; + } + + /* Don't allow setxid until cloned. */ + result->setxid_futex = -1; + + /* 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)); + for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt) + free (dtv[1 + cnt].pointer.to_free); + 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 (__glibc_unlikely (stack_cache_actsize > stack_cache_maxsize)) + __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 _STACK_GROWS_DOWN + void *stack = pd->stackblock + pd->guardsize; + size_t len = pd->stackblock_size - pd->guardsize; +#elif _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 + if (mprotect (stack, len, PROT_READ | PROT_WRITE | PROT_EXEC) != 0) + return errno; + + return 0; +} + + +/* Returns a usable stack for a new thread either by allocating a + new stack or reusing a cached stack of sufficient size. + ATTR must be non-NULL and point to a valid pthread_attr. + PDP must be non-NULL. */ +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; + + 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. */ + if (attr->stacksize != 0) + size = attr->stacksize; + else + { + lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); + size = __default_pthread_attr.stacksize; + lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); + } + + /* Get memory for the stack. */ + if (__glibc_unlikely (attr->flags & ATTR_FLAG_STACKADDR)) + { + uintptr_t adj; + char *stackaddr = (char *) attr->stackaddr; + + /* Assume the same layout as the _STACK_GROWS_DOWN case, with struct + pthread at the top of the stack block. Later we adjust the guard + location and stack address to match the _STACK_GROWS_UP case. */ + if (_STACK_GROWS_UP) + stackaddr += attr->stacksize; + + /* 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) stackaddr - TLS_TCB_SIZE) + & __static_tls_align_m1; + assert (size > adj + TLS_TCB_SIZE); +#elif TLS_DTV_AT_TP + adj = ((uintptr_t) 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) stackaddr + - TLS_TCB_SIZE - adj); +#elif TLS_DTV_AT_TP + pd = (struct pthread *) (((uintptr_t) 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 *) 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 + SETUP_THREAD_SYSINFO (pd); +#endif + + /* Don't allow setxid until cloned. */ + pd->setxid_futex = -1; + + /* Allocate the DTV for this thread. */ + if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL) + { + /* Something went wrong. */ + assert (errno == ENOMEM); + return errno; + } + + + /* 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; + const int prot = (PROT_READ | PROT_WRITE + | ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0)); + + /* 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 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 (__glibc_unlikely (mem == MAP_FAILED)) + return errno; + + /* SIZE is guaranteed to be greater than zero. + So we can never get a null pointer back from mmap. */ + assert (mem != NULL); + + /* Place the thread descriptor at the end of the stack. */ +#if TLS_TCB_AT_TP + pd = (struct pthread *) ((char *) mem + size) - 1; +#elif TLS_DTV_AT_TP + pd = (struct pthread *) ((((uintptr_t) mem + size + - __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 + SETUP_THREAD_SYSINFO (pd); +#endif + + /* Don't allow setxid until cloned. */ + pd->setxid_futex = -1; + + /* 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 errno; + } + + + /* 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); + + + /* 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 (__glibc_unlikely (guardsize > pd->guardsize)) + { +#ifdef NEED_SEPARATE_REGISTER_STACK + char *guard = mem + (((size - guardsize) / 2) & ~pagesize_m1); +#elif _STACK_GROWS_DOWN + char *guard = mem; +#elif _STACK_GROWS_UP + char *guard = (char *) (((uintptr_t) pd - guardsize) & ~pagesize_m1); +#endif + if (mprotect (guard, guardsize, PROT_NONE) != 0) + { + mprot_error: + 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 errno; + } + + 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; +#elif _STACK_GROWS_DOWN + if (mprotect ((char *) mem + guardsize, pd->guardsize - guardsize, + prot) != 0) + goto mprot_error; +#elif _STACK_GROWS_UP + if (mprotect ((char *) pd - pd->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; + + /* 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 _STACK_GROWS_DOWN + void *stacktop; + +# 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 +#else + *stack = pd->stackblock; +#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 (__glibc_likely (! pd->user_stack)) + (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 = _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, 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 *) (in_flight_stack & ~(uintptr_t) 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 to see if the + pointers at the head of the list are inconsistent. */ + list_t *l = NULL; + + if (stack_used.next->prev != &stack_used) + l = &stack_used; + else if (stack_cache.next->prev != &stack_cache) + l = &stack_cache; + + if (l != NULL) + { + assert (l->next->prev == elem); + elem->next = l->next; + elem->prev = l; + l->next = elem; + } + } + 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; + + for (size_t 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 (__glibc_unlikely (THREAD_GETMEM (self, user_stack))) + 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 locks. */ + stack_cache_lock = LLL_LOCK_INITIALIZER; + __default_pthread_attr_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, LLL_PRIVATE); + + /* 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, LLL_PRIVATE); + + return result; +} +#endif + + +#ifdef SIGSETXID +static void +internal_function +setxid_mark_thread (struct xid_command *cmdp, struct pthread *t) +{ + int ch; + + /* Wait until this thread is cloned. */ + if (t->setxid_futex == -1 + && ! atomic_compare_and_exchange_bool_acq (&t->setxid_futex, -2, -1)) + do + futex_wait_simple (&t->setxid_futex, -2, FUTEX_PRIVATE); + while (t->setxid_futex == -2); + + /* 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) + { + /* Release the futex if there is no other setxid in + progress. */ + if ((ch & SETXID_BITMASK) == 0) + { + t->setxid_futex = 1; + futex_wake (&t->setxid_futex, 1, FUTEX_PRIVATE); + } + 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; + futex_wake (&t->setxid_futex, 1, FUTEX_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_CALL (tgkill, err, 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; +} + +/* Check for consistency across set*id system call results. The abort + should not happen as long as all privileges changes happen through + the glibc wrappers. ERROR must be 0 (no error) or an errno + code. */ +void +attribute_hidden +__nptl_setxid_error (struct xid_command *cmdp, int error) +{ + do + { + int olderror = cmdp->error; + if (olderror == error) + break; + if (olderror != -1) + /* Mismatch between current and previous results. */ + abort (); + } + while (atomic_compare_and_exchange_bool_acq (&cmdp->error, error, -1)); +} + +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; + cmdp->error = -1; + + 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) + { + futex_wait_simple ((unsigned int *) &cmdp->cntr, cur, + FUTEX_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]); + int error = 0; + if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err))) + { + error = INTERNAL_SYSCALL_ERRNO (result, err); + __set_errno (error); + result = -1; + } + __nptl_setxid_error (cmdp, error); + + lll_unlock (stack_cache_lock, LLL_PRIVATE); + return result; +} +#endif /* SIGSETXID. */ + + +static inline void __attribute__((always_inline)) +init_one_static_tls (struct pthread *curp, struct link_map *map) +{ +# 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 + + /* 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 + futex_wait_simple ((unsigned int *) gscope_flagp, + THREAD_GSCOPE_FLAG_WAIT, FUTEX_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 + futex_wait_simple ((unsigned int *) gscope_flagp, + THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE); + while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT); + } + + lll_unlock (stack_cache_lock, LLL_PRIVATE); +} |