FreeBSD-5.3/lib/libpthread/thread/thr_stack.c
/*
* 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: src/lib/libpthread/thread/thr_stack.c,v 1.8.4.1 2004/10/09 10:21:19 davidxu Exp $
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/queue.h>
#include <stdlib.h>
#include <pthread.h>
#include "thr_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 mapped with PROT_NONE) 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 = NULL;
/*
* Round size up to the nearest multiple of
* _thr_page_size.
*/
static inline size_t
round_up(size_t size)
{
if (size % _thr_page_size != 0)
size = ((size / _thr_page_size) + 1) *
_thr_page_size;
return size;
}
int
_thr_stack_alloc(struct pthread_attr *attr)
{
struct stack *spare_stack;
struct kse *curkse;
kse_critical_t crit;
size_t stacksize;
size_t guardsize;
char *stackaddr;
/*
* Round up stack size to nearest multiple of _thr_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.
*/
stacksize = round_up(attr->stacksize_attr);
guardsize = round_up(attr->guardsize_attr);
attr->stackaddr_attr = NULL;
attr->flags &= ~THR_STACK_USER;
/*
* Use the garbage collector lock for synchronization of the
* spare stack lists and allocations from usrstack.
*/
crit = _kse_critical_enter();
curkse = _get_curkse();
KSE_LOCK_ACQUIRE(curkse, &_thread_list_lock);
/*
* If the stack and guard sizes are default, try to allocate a stack
* from the default-size stack cache:
*/
if ((stacksize == THR_STACK_DEFAULT) &&
(guardsize == _thr_guard_default)) {
if ((spare_stack = LIST_FIRST(&dstackq)) != NULL) {
/* Use the spare stack. */
LIST_REMOVE(spare_stack, qe);
attr->stackaddr_attr = spare_stack->stackaddr;
}
}
/*
* 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 {
LIST_FOREACH(spare_stack, &mstackq, qe) {
if (spare_stack->stacksize == stacksize &&
spare_stack->guardsize == guardsize) {
LIST_REMOVE(spare_stack, qe);
attr->stackaddr_attr = spare_stack->stackaddr;
break;
}
}
}
if (attr->stackaddr_attr != NULL) {
/* A cached stack was found. Release the lock. */
KSE_LOCK_RELEASE(curkse, &_thread_list_lock);
_kse_critical_leave(crit);
}
else {
/* Allocate a stack from usrstack. */
if (last_stack == NULL)
last_stack = _usrstack - THR_STACK_INITIAL -
_thr_guard_default;
/* Allocate a new stack. */
stackaddr = last_stack - stacksize - guardsize;
/*
* 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 -= (stacksize + guardsize);
/* Release the lock before mmap'ing it. */
KSE_LOCK_RELEASE(curkse, &_thread_list_lock);
_kse_critical_leave(crit);
/* Map the stack and guard page together, and split guard
page from allocated space: */
if ((stackaddr = mmap(stackaddr, stacksize+guardsize,
PROT_READ | PROT_WRITE, MAP_STACK,
-1, 0)) != MAP_FAILED &&
(guardsize == 0 ||
mprotect(stackaddr, guardsize, PROT_NONE) == 0)) {
stackaddr += guardsize;
} else {
if (stackaddr != MAP_FAILED)
munmap(stackaddr, stacksize + guardsize);
stackaddr = NULL;
}
attr->stackaddr_attr = stackaddr;
}
if (attr->stackaddr_attr != NULL)
return (0);
else
return (-1);
}
/* This function must be called with _thread_list_lock held. */
void
_thr_stack_free(struct pthread_attr *attr)
{
struct stack *spare_stack;
if ((attr != NULL) && ((attr->flags & THR_STACK_USER) == 0)
&& (attr->stackaddr_attr != NULL)) {
spare_stack = (attr->stackaddr_attr + attr->stacksize_attr
- sizeof(struct stack));
spare_stack->stacksize = round_up(attr->stacksize_attr);
spare_stack->guardsize = round_up(attr->guardsize_attr);
spare_stack->stackaddr = attr->stackaddr_attr;
if (spare_stack->stacksize == THR_STACK_DEFAULT &&
spare_stack->guardsize == _thr_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);
}
attr->stackaddr_attr = NULL;
}
}