1 /*
2 * Copyright (c) 1998, 2007, 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 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_threadLS_solaris_x86.cpp.incl"
27
28 #ifdef AMD64
29 extern "C" Thread* fs_load(ptrdiff_t tlsOffset);
30 extern "C" intptr_t fs_thread();
31 #else
32 // From solaris_i486.s
33 extern "C" Thread* gs_load(ptrdiff_t tlsOffset);
34 extern "C" intptr_t gs_thread();
35 #endif // AMD64
36
37 // tlsMode encoding:
38 //
39 // pd_tlsAccessUndefined : uninitialized
40 // pd_tlsAccessSlow : not available
41 // pd_tlsAccessIndirect :
42 // old-style indirect access - present in "T1" libthread.
43 // use thr_slot_sync_allocate() to attempt to allocate a slot.
44 // pd_tlsAccessDirect :
45 // new-style direct access - present in late-model "T2" libthread.
46 // Allocate the offset (slot) via _thr_slot_offset() or by
47 // defining an IE- or LE-mode TLS/TSD slot in the launcher and then passing
48 // that offset into libjvm.so.
49 // See http://sac.eng/Archives/CaseLog/arc/PSARC/2003/159/.
50 //
51 // Note that we have a capability gap - some early model T2 forms
52 // (e.g., unpatched S9) have neither _thr_slot_sync_allocate() nor
53 // _thr_slot_offset(). In that case we revert to the usual
54 // thr_getspecific accessor.
55 //
56
57 static ThreadLocalStorage::pd_tlsAccessMode tlsMode = ThreadLocalStorage::pd_tlsAccessUndefined ;
58 static ptrdiff_t tlsOffset = 0 ;
59 static thread_key_t tlsKey ;
60
61 typedef int (*TSSA_Entry) (ptrdiff_t *, int, int) ;
62 typedef ptrdiff_t (*TSO_Entry) (int) ;
63
64 ThreadLocalStorage::pd_tlsAccessMode ThreadLocalStorage::pd_getTlsAccessMode ()
65 {
66 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
67 return tlsMode ;
68 }
69
70 ptrdiff_t ThreadLocalStorage::pd_getTlsOffset () {
71 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
72 return tlsOffset ;
73 }
74
75 // TODO: Consider the following improvements:
76 //
77 // 1. Convert from thr_*specific* to pthread_*specific*.
78 // The pthread_ forms are slightly faster. Also, the
79 // pthread_ forms have a pthread_key_delete() API which
80 // would aid in clean JVM shutdown and the eventual goal
81 // of permitting a JVM to reinstantiate itself withing a process.
82 //
83 // 2. See ThreadLocalStorage::init(). We end up allocating
84 // two TLS keys during VM startup. That's benign, but we could collapse
85 // down to one key without too much trouble.
86 //
87 // 3. MacroAssembler::get_thread() currently emits calls to thr_getspecific().
88 // Modify get_thread() to call Thread::current() instead.
89 //
90 // 4. Thread::current() currently uses a cache keyed by %gs:[0].
91 // (The JVM has PSARC permission to use %g7/%gs:[0]
92 // as an opaque temporally unique thread identifier).
93 // For C++ access to a thread's reflexive "self" pointer we
94 // should consider using one of the following:
95 // a. a radix tree keyed by %esp - as in EVM.
96 // This requires two loads (the 2nd dependent on the 1st), but
97 // is easily inlined and doesn't require a "miss" slow path.
98 // b. a fast TLS/TSD slot allocated by _thr_slot_offset
99 // or _thr_slot_sync_allocate.
100 //
101 // 5. 'generate_code_for_get_thread' is a misnomer.
102 // We should change it to something more general like
103 // pd_ThreadSelf_Init(), for instance.
104 //
105
106 static void AllocateTLSOffset ()
107 {
108 int rslt ;
109 TSSA_Entry tssa ;
110 TSO_Entry tso ;
111 ptrdiff_t off ;
112
113 guarantee (tlsMode == ThreadLocalStorage::pd_tlsAccessUndefined, "tlsMode not set") ;
114 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ;
115 tlsOffset = 0 ;
116 #ifndef AMD64
117
118 tssa = (TSSA_Entry) dlsym (RTLD_DEFAULT, "thr_slot_sync_allocate") ;
119 if (tssa != NULL) {
120 off = -1 ;
121 rslt = (*tssa)(&off, NULL, NULL) ; // (off,dtor,darg)
122 if (off != -1) {
123 tlsOffset = off ;
124 tlsMode = ThreadLocalStorage::pd_tlsAccessIndirect ;
125 return ;
126 }
127 }
128
129 rslt = thr_keycreate (&tlsKey, NULL) ;
130 if (rslt != 0) {
131 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ; // revert to slow mode
132 return ;
133 }
134
135 tso = (TSO_Entry) dlsym (RTLD_DEFAULT, "_thr_slot_offset") ;
136 if (tso != NULL) {
137 off = (*tso)(tlsKey) ;
138 if (off >= 0) {
139 tlsOffset = off ;
140 tlsMode = ThreadLocalStorage::pd_tlsAccessDirect ;
141 return ;
142 }
143 }
144
145 // Failure: Too bad ... we've allocated a TLS slot we don't need and there's
146 // no provision in the ABI for returning the slot.
147 //
148 // If we didn't find a slot then then:
149 // 1. We might be on liblwp.
150 // 2. We might be on T2 libthread, but all "fast" slots are already
151 // consumed
152 // 3. We might be on T1, and all TSD (thr_slot_sync_allocate) slots are
153 // consumed.
154 // 4. We might be on T2 libthread, but it's be re-architected
155 // so that fast slots are no longer g7-relative.
156 //
157
158 tlsMode = ThreadLocalStorage::pd_tlsAccessSlow ;
159 return ;
160 #endif // AMD64
161 }
162
163 void ThreadLocalStorage::generate_code_for_get_thread() {
164 AllocateTLSOffset() ;
165 }
166
167 void ThreadLocalStorage::set_thread_in_slot(Thread *thread) {
168 guarantee (tlsMode != pd_tlsAccessUndefined, "tlsMode not set") ;
169 if (tlsMode == pd_tlsAccessIndirect) {
170 #ifdef AMD64
171 intptr_t tbase = fs_thread();
172 #else
173 intptr_t tbase = gs_thread();
174 #endif // AMD64
175 *((Thread**) (tbase + tlsOffset)) = thread ;
176 } else
177 if (tlsMode == pd_tlsAccessDirect) {
178 thr_setspecific (tlsKey, (void *) thread) ;
179 // set with thr_setspecific and then readback with gs_load to validate.
180 #ifdef AMD64
181 guarantee (thread == fs_load(tlsOffset), "tls readback failure") ;
182 #else
183 guarantee (thread == gs_load(tlsOffset), "tls readback failure") ;
184 #endif // AMD64
185 }
186 }
187
188
189 extern "C" Thread* get_thread() {
190 return ThreadLocalStorage::thread();
191 }