michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "primpl.h"
michael@0: 
michael@0: /* List of free stack virtual memory chunks */
michael@0: PRLock *_pr_stackLock;
michael@0: PRCList _pr_freeStacks = PR_INIT_STATIC_CLIST(&_pr_freeStacks);
michael@0: PRIntn _pr_numFreeStacks;
michael@0: PRIntn _pr_maxFreeStacks = 4;
michael@0: 
michael@0: #ifdef DEBUG
michael@0: /*
michael@0: ** A variable that can be set via the debugger...
michael@0: */
michael@0: PRBool _pr_debugStacks = PR_FALSE;
michael@0: #endif
michael@0: 
michael@0: /* How much space to leave between the stacks, at each end */
michael@0: #define REDZONE		(2 << _pr_pageShift)
michael@0: 
michael@0: #define _PR_THREAD_STACK_PTR(_qp) \
michael@0:     ((PRThreadStack*) ((char*) (_qp) - offsetof(PRThreadStack,links)))
michael@0: 
michael@0: void _PR_InitStacks(void)
michael@0: {
michael@0:     _pr_stackLock = PR_NewLock();
michael@0: }
michael@0: 
michael@0: void _PR_CleanupStacks(void)
michael@0: {
michael@0:     if (_pr_stackLock) {
michael@0:         PR_DestroyLock(_pr_stackLock);
michael@0:         _pr_stackLock = NULL;
michael@0:     }
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Allocate a stack for a thread.
michael@0: */
michael@0: PRThreadStack *_PR_NewStack(PRUint32 stackSize)
michael@0: {
michael@0:     PRCList *qp;
michael@0:     PRThreadStack *ts;
michael@0:     PRThread *thr;
michael@0: 
michael@0:     /*
michael@0:     ** Trim the list of free stacks. Trim it backwards, tossing out the
michael@0:     ** oldest stack found first (this way more recent stacks have a
michael@0:     ** chance of being present in the data cache).
michael@0:     */
michael@0:     PR_Lock(_pr_stackLock);
michael@0:     qp = _pr_freeStacks.prev;
michael@0:     while ((_pr_numFreeStacks > _pr_maxFreeStacks) && (qp != &_pr_freeStacks)) {
michael@0: 	ts = _PR_THREAD_STACK_PTR(qp);
michael@0: 	thr = _PR_THREAD_STACK_TO_PTR(ts);
michael@0: 	qp = qp->prev;
michael@0: 	/*
michael@0: 	 * skip stacks which are still being used
michael@0: 	 */
michael@0: 	if (thr->no_sched)
michael@0: 		continue;
michael@0: 	PR_REMOVE_LINK(&ts->links);
michael@0: 
michael@0: 	/* Give platform OS to clear out the stack for debugging */
michael@0: 	_PR_MD_CLEAR_STACK(ts);
michael@0: 
michael@0: 	_pr_numFreeStacks--;
michael@0: 	_PR_DestroySegment(ts->seg);
michael@0: 	PR_DELETE(ts);
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:     ** Find a free thread stack. This searches the list of free'd up
michael@0:     ** virtually mapped thread stacks.
michael@0:     */
michael@0:     qp = _pr_freeStacks.next;
michael@0:     ts = 0;
michael@0:     while (qp != &_pr_freeStacks) {
michael@0: 	ts = _PR_THREAD_STACK_PTR(qp);
michael@0: 	thr = _PR_THREAD_STACK_TO_PTR(ts);
michael@0: 	qp = qp->next;
michael@0: 	/*
michael@0: 	 * skip stacks which are still being used
michael@0: 	 */
michael@0: 	if ((!(thr->no_sched)) && ((ts->allocSize - 2*REDZONE) >= stackSize)) {
michael@0: 	    /*
michael@0: 	    ** Found a stack that is not in use and is big enough. Change
michael@0: 	    ** stackSize to fit it.
michael@0: 	    */
michael@0: 	    stackSize = ts->allocSize - 2*REDZONE;
michael@0: 	    PR_REMOVE_LINK(&ts->links);
michael@0: 	    _pr_numFreeStacks--;
michael@0: 	    ts->links.next = 0;
michael@0: 	    ts->links.prev = 0;
michael@0: 	    PR_Unlock(_pr_stackLock);
michael@0: 	    goto done;
michael@0: 	}
michael@0: 	ts = 0;
michael@0:     }
michael@0:     PR_Unlock(_pr_stackLock);
michael@0: 
michael@0:     if (!ts) {
michael@0: 	/* Make a new thread stack object. */
michael@0: 	ts = PR_NEWZAP(PRThreadStack);
michael@0: 	if (!ts) {
michael@0: 	    return NULL;
michael@0: 	}
michael@0: 
michael@0: 	/*
michael@0: 	** Assign some of the virtual space to the new stack object. We
michael@0: 	** may not get that piece of VM, but if nothing else we will
michael@0: 	** advance the pointer so we don't collide (unless the OS screws
michael@0: 	** up).
michael@0: 	*/
michael@0: 	ts->allocSize = stackSize + 2*REDZONE;
michael@0: 	ts->seg = _PR_NewSegment(ts->allocSize, 0);
michael@0: 	if (!ts->seg) {
michael@0: 	    PR_DELETE(ts);
michael@0: 	    return NULL;
michael@0: 	}
michael@0: 	}
michael@0: 
michael@0:   done:
michael@0:     ts->allocBase = (char*)ts->seg->vaddr;
michael@0:     ts->flags = _PR_STACK_MAPPED;
michael@0:     ts->stackSize = stackSize;
michael@0: 
michael@0: #ifdef HAVE_STACK_GROWING_UP
michael@0:     ts->stackTop = ts->allocBase + REDZONE;
michael@0:     ts->stackBottom = ts->stackTop + stackSize;
michael@0: #else
michael@0:     ts->stackBottom = ts->allocBase + REDZONE;
michael@0:     ts->stackTop = ts->stackBottom + stackSize;
michael@0: #endif
michael@0: 
michael@0:     PR_LOG(_pr_thread_lm, PR_LOG_NOTICE,
michael@0: 	   ("thread stack: base=0x%x limit=0x%x bottom=0x%x top=0x%x\n",
michael@0: 	    ts->allocBase, ts->allocBase + ts->allocSize - 1,
michael@0: 	    ts->allocBase + REDZONE,
michael@0: 	    ts->allocBase + REDZONE + stackSize - 1));
michael@0: 	    
michael@0:     _PR_MD_INIT_STACK(ts,REDZONE);
michael@0: 
michael@0:     return ts;
michael@0: }
michael@0: 
michael@0: /*
michael@0: ** Free the stack for the current thread
michael@0: */
michael@0: void _PR_FreeStack(PRThreadStack *ts)
michael@0: {
michael@0:     if (!ts) {
michael@0: 	return;
michael@0:     }
michael@0:     if (ts->flags & _PR_STACK_PRIMORDIAL) {
michael@0: 	PR_DELETE(ts);
michael@0: 	return;
michael@0:     }
michael@0: 
michael@0:     /*
michael@0:     ** Put the stack on the free list. This is done because we are still
michael@0:     ** using the stack. Next time a thread is created we will trim the
michael@0:     ** list down; it's safe to do it then because we will have had to
michael@0:     ** context switch to a live stack before another thread can be
michael@0:     ** created.
michael@0:     */
michael@0:     PR_Lock(_pr_stackLock);
michael@0:     PR_APPEND_LINK(&ts->links, _pr_freeStacks.prev);
michael@0:     _pr_numFreeStacks++;
michael@0:     PR_Unlock(_pr_stackLock);
michael@0: }