Mercurial > hg > truffle
diff src/os_cpu/bsd_x86/vm/threadLS_bsd_x86.cpp @ 3960:f08d439fab8c
7089790: integrate bsd-port changes
Reviewed-by: kvn, twisti, jrose
Contributed-by: Kurt Miller <kurt@intricatesoftware.com>, Greg Lewis <glewis@eyesbeyond.com>, Jung-uk Kim <jkim@freebsd.org>, Christos Zoulas <christos@zoulas.com>, Landon Fuller <landonf@plausible.coop>, The FreeBSD Foundation <board@freebsdfoundation.org>, Michael Franz <mvfranz@gmail.com>, Roger Hoover <rhoover@apple.com>, Alexander Strange <astrange@apple.com>
author | never |
---|---|
date | Sun, 25 Sep 2011 16:03:29 -0700 |
parents | |
children | f34d701e952e |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/os_cpu/bsd_x86/vm/threadLS_bsd_x86.cpp Sun Sep 25 16:03:29 2011 -0700 @@ -0,0 +1,92 @@ +/* + * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "runtime/threadLocalStorage.hpp" +#include "thread_bsd.inline.hpp" + +// Map stack pointer (%esp) to thread pointer for faster TLS access +// +// Here we use a flat table for better performance. Getting current thread +// is down to one memory access (read _sp_map[%esp>>12]) in generated code +// and two in runtime code (-fPIC code needs an extra load for _sp_map). +// +// This code assumes stack page is not shared by different threads. It works +// in 32-bit VM when page size is 4K (or a multiple of 4K, if that matters). +// +// Notice that _sp_map is allocated in the bss segment, which is ZFOD +// (zero-fill-on-demand). While it reserves 4M address space upfront, +// actual memory pages are committed on demand. +// +// If an application creates and destroys a lot of threads, usually the +// stack space freed by a thread will soon get reused by new thread +// (this is especially true in NPTL or BsdThreads in fixed-stack mode). +// No memory page in _sp_map is wasted. +// +// However, it's still possible that we might end up populating & +// committing a large fraction of the 4M table over time, but the actual +// amount of live data in the table could be quite small. The max wastage +// is less than 4M bytes. If it becomes an issue, we could use madvise() +// with MADV_DONTNEED to reclaim unused (i.e. all-zero) pages in _sp_map. +// MADV_DONTNEED on Bsd keeps the virtual memory mapping, but zaps the +// physical memory page (i.e. similar to MADV_FREE on Solaris). + +#ifndef AMD64 +Thread* ThreadLocalStorage::_sp_map[1UL << (SP_BITLENGTH - PAGE_SHIFT)]; +#endif // !AMD64 + +void ThreadLocalStorage::generate_code_for_get_thread() { + // nothing we can do here for user-level thread +} + +void ThreadLocalStorage::pd_init() { +#ifndef AMD64 + assert(align_size_down(os::vm_page_size(), PAGE_SIZE) == os::vm_page_size(), + "page size must be multiple of PAGE_SIZE"); +#endif // !AMD64 +} + +void ThreadLocalStorage::pd_set_thread(Thread* thread) { + os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); + +#ifndef AMD64 + address stack_top = os::current_stack_base(); + size_t stack_size = os::current_stack_size(); + + for (address p = stack_top - stack_size; p < stack_top; p += PAGE_SIZE) { + // pd_set_thread() is called with non-NULL value when a new thread is + // created/attached, or with NULL value when a thread is about to exit. + // If both "thread" and the corresponding _sp_map[] entry are non-NULL, + // they should have the same value. Otherwise it might indicate that the + // stack page is shared by multiple threads. However, a more likely cause + // for this assertion to fail is that an attached thread exited without + // detaching itself from VM, which is a program error and could cause VM + // to crash. + assert(thread == NULL || _sp_map[(uintptr_t)p >> PAGE_SHIFT] == NULL || + thread == _sp_map[(uintptr_t)p >> PAGE_SHIFT], + "thread exited without detaching from VM??"); + _sp_map[(uintptr_t)p >> PAGE_SHIFT] = thread; + } +#endif // !AMD64 +}