diff options
Diffstat (limited to 'lib/libpthread/thread/thr_stack.c')
| -rw-r--r-- | lib/libpthread/thread/thr_stack.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_stack.c b/lib/libpthread/thread/thr_stack.c new file mode 100644 index 0000000..86f0a2d --- /dev/null +++ b/lib/libpthread/thread/thr_stack.c @@ -0,0 +1,237 @@ +/* + * Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org> + * Copyright (c) 2000-2001 Jason Evans <jasone@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ +#include <sys/types.h> +#include <sys/mman.h> +#include <sys/param.h> +#include <sys/queue.h> +#include <sys/user.h> +#include <stdlib.h> +#include <pthread.h> +#include "pthread_private.h" + +/* Spare thread stack. */ +struct stack { + LIST_ENTRY(stack) qe; /* Stack queue linkage. */ + size_t stacksize; /* Stack size (rounded up). */ + size_t guardsize; /* Guard size. */ + void *stackaddr; /* Stack address. */ +}; + +/* + * Default sized (stack and guard) spare stack queue. Stacks are cached to + * avoid additional complexity managing mmap()ed stack regions. Spare stacks + * are used in LIFO order to increase cache locality. + */ +static LIST_HEAD(, stack) _dstackq = LIST_HEAD_INITIALIZER(_dstackq); + +/* + * Miscellaneous sized (non-default stack and/or guard) spare stack queue. + * Stacks are cached to avoid additional complexity managing mmap()ed stack + * regions. This list is unordered, since ordering on both stack size and guard + * size would be more trouble than it's worth. Stacks are allocated from this + * cache on a first size match basis. + */ +static LIST_HEAD(, stack) _mstackq = LIST_HEAD_INITIALIZER(_mstackq); + +/** + * Base address of the last stack allocated (including its red zone, if there is + * one). Stacks are allocated contiguously, starting beyond the top of the main + * stack. When a new stack is created, a red zone is typically created + * (actually, the red zone is simply left unmapped) above the top of the stack, + * such that the stack will not be able to grow all the way to the bottom of the + * next stack. This isn't fool-proof. It is possible for a stack to grow by a + * large amount, such that it grows into the next stack, and as long as the + * memory within the red zone is never accessed, nothing will prevent one thread + * stack from trouncing all over the next. + * + * low memory + * . . . . . . . . . . . . . . . . . . + * | | + * | stack 3 | start of 3rd thread stack + * +-----------------------------------+ + * | | + * | Red Zone (guard page) | red zone for 2nd thread + * | | + * +-----------------------------------+ + * | stack 2 - PTHREAD_STACK_DEFAULT | top of 2nd thread stack + * | | + * | | + * | | + * | | + * | stack 2 | + * +-----------------------------------+ <-- start of 2nd thread stack + * | | + * | Red Zone | red zone for 1st thread + * | | + * +-----------------------------------+ + * | stack 1 - PTHREAD_STACK_DEFAULT | top of 1st thread stack + * | | + * | | + * | | + * | | + * | stack 1 | + * +-----------------------------------+ <-- start of 1st thread stack + * | | (initial value of last_stack) + * | Red Zone | + * | | red zone for main thread + * +-----------------------------------+ + * | USRSTACK - PTHREAD_STACK_INITIAL | top of main thread stack + * | | ^ + * | | | + * | | | + * | | | stack growth + * | | + * +-----------------------------------+ <-- start of main thread stack + * (USRSTACK) + * high memory + * + */ +static void * last_stack; + +void * +_thread_stack_alloc(size_t stacksize, size_t guardsize) +{ + void *stack = NULL; + struct stack *spare_stack; + size_t stack_size; + + /* + * Round up stack size to nearest multiple of PAGE_SIZE, so that mmap() + * will work. If the stack size is not an even multiple, we end up + * initializing things such that there is unused space above the + * beginning of the stack, so the stack sits snugly against its guard. + */ + if (stacksize % PAGE_SIZE != 0) + stack_size = ((stacksize / PAGE_SIZE) + 1) * PAGE_SIZE; + else + stack_size = stacksize; + + /* + * If the stack and guard sizes are default, try to allocate a stack + * from the default-size stack cache: + */ + if (stack_size == PTHREAD_STACK_DEFAULT && + guardsize == PTHREAD_GUARD_DEFAULT) { + /* + * Use the garbage collector mutex for synchronization of the + * spare stack list. + */ + if (pthread_mutex_lock(&_gc_mutex) != 0) + PANIC("Cannot lock gc mutex"); + + if ((spare_stack = LIST_FIRST(&_dstackq)) != NULL) { + /* Use the spare stack. */ + LIST_REMOVE(spare_stack, qe); + stack = spare_stack->stackaddr; + } + + /* Unlock the garbage collector mutex. */ + if (pthread_mutex_unlock(&_gc_mutex) != 0) + PANIC("Cannot unlock gc mutex"); + } + /* + * The user specified a non-default stack and/or guard size, so try to + * allocate a stack from the non-default size stack cache, using the + * rounded up stack size (stack_size) in the search: + */ + else { + /* + * Use the garbage collector mutex for synchronization of the + * spare stack list. + */ + if (pthread_mutex_lock(&_gc_mutex) != 0) + PANIC("Cannot lock gc mutex"); + + LIST_FOREACH(spare_stack, &_mstackq, qe) { + if (spare_stack->stacksize == stack_size && + spare_stack->guardsize == guardsize) { + LIST_REMOVE(spare_stack, qe); + stack = spare_stack->stackaddr; + break; + } + } + + /* Unlock the garbage collector mutex. */ + if (pthread_mutex_unlock(&_gc_mutex) != 0) + PANIC("Cannot unlock gc mutex"); + } + + /* Check if a stack was not allocated from a stack cache: */ + if (stack == NULL) { + + if (last_stack == NULL) + last_stack = _usrstack - PTHREAD_STACK_INITIAL - + PTHREAD_GUARD_DEFAULT; + + /* Allocate a new stack. */ + stack = last_stack - stack_size; + + /* + * Even if stack allocation fails, we don't want to try to use + * this location again, so unconditionally decrement + * last_stack. Under normal operating conditions, the most + * likely reason for an mmap() error is a stack overflow of the + * adjacent thread stack. + */ + last_stack -= (stack_size + guardsize); + + /* Stack: */ + if (mmap(stack, stack_size, PROT_READ | PROT_WRITE, MAP_STACK, + -1, 0) == MAP_FAILED) + stack = NULL; + } + + return (stack); +} + +/* This function must be called with _gc_mutex held. */ +void +_thread_stack_free(void *stack, size_t stacksize, size_t guardsize) +{ + struct stack *spare_stack; + + spare_stack = (stack + stacksize - sizeof(struct stack)); + /* Round stacksize up to nearest multiple of PAGE_SIZE. */ + if (stacksize % PAGE_SIZE != 0) { + spare_stack->stacksize = ((stacksize / PAGE_SIZE) + 1) * + PAGE_SIZE; + } else + spare_stack->stacksize = stacksize; + spare_stack->guardsize = guardsize; + spare_stack->stackaddr = stack; + + if (spare_stack->stacksize == PTHREAD_STACK_DEFAULT && + spare_stack->guardsize == PTHREAD_GUARD_DEFAULT) { + /* Default stack/guard size. */ + LIST_INSERT_HEAD(&_dstackq, spare_stack, qe); + } else { + /* Non-default stack/guard size. */ + LIST_INSERT_HEAD(&_mstackq, spare_stack, qe); + } +} |
