Wed, 25 Sep 2013 13:58:13 +0200
8023956: Provide a work-around to broken Linux 32 bit "Exec Shield" using CS for NX emulation (crashing with SI_KERNEL)
Summary: Execute some code at a high virtual address value, and keep mapped
Reviewed-by: coleenp, zgu
1 /*
2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef OS_CPU_LINUX_X86_VM_THREADLS_LINUX_X86_HPP
26 #define OS_CPU_LINUX_X86_VM_THREADLS_LINUX_X86_HPP
28 // Processor dependent parts of ThreadLocalStorage
30 #if !defined(AMD64) && !defined(MINIMIZE_RAM_USAGE)
32 // map stack pointer to thread pointer - see notes in threadLS_linux_x86.cpp
33 #define SP_BITLENGTH 32
34 #define PAGE_SHIFT 12
35 #define PAGE_SIZE (1UL << PAGE_SHIFT)
36 static Thread* _sp_map[1UL << (SP_BITLENGTH - PAGE_SHIFT)];
38 public:
40 static Thread** sp_map_addr() { return _sp_map; }
42 static Thread* thread() {
43 uintptr_t sp;
44 __asm__ volatile ("movl %%esp, %0" : "=r" (sp));
45 return _sp_map[sp >> PAGE_SHIFT];
46 }
48 #else
50 public:
52 static Thread* thread() {
53 return (Thread*) os::thread_local_storage_at(thread_index());
54 }
56 #endif // AMD64 || MINIMIZE_RAM_USAGE
58 #endif // OS_CPU_LINUX_X86_VM_THREADLS_LINUX_X86_HPP