diff options
Diffstat (limited to 'lib/libpthread/thread')
| -rw-r--r-- | lib/libpthread/thread/thr_stack.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/lib/libpthread/thread/thr_stack.c b/lib/libpthread/thread/thr_stack.c index 9714593..484eb81 100644 --- a/lib/libpthread/thread/thr_stack.c +++ b/lib/libpthread/thread/thr_stack.c @@ -61,7 +61,7 @@ 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 + * 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 @@ -134,6 +134,7 @@ _thr_stack_alloc(struct pthread_attr *attr) kse_critical_t crit; size_t stacksize; size_t guardsize; + char *stackaddr; /* * Round up stack size to nearest multiple of _thr_page_size so @@ -194,7 +195,7 @@ _thr_stack_alloc(struct pthread_attr *attr) _thr_guard_default; /* Allocate a new stack. */ - attr->stackaddr_attr = last_stack - stacksize; + stackaddr = last_stack - stacksize - guardsize; /* * Even if stack allocation fails, we don't want to try to @@ -209,11 +210,20 @@ _thr_stack_alloc(struct pthread_attr *attr) KSE_LOCK_RELEASE(curkse, &_thread_list_lock); _kse_critical_leave(crit); - /* Map the stack, but not the guard page: */ - if ((attr->stackaddr_attr = mmap(attr->stackaddr_attr, - stacksize, PROT_READ | PROT_WRITE, MAP_STACK, - -1, 0)) == MAP_FAILED) - attr->stackaddr_attr = NULL; + /* 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); |
