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