1/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#ifndef _DESCR_H
20#define _DESCR_H 1
21
22#include <limits.h>
23#include <sched.h>
24#include <setjmp.h>
25#include <stdbool.h>
26#include <sys/types.h>
27#include <hp-timing.h>
28#define __need_list_t
29#include <list.h>
30#include <lowlevellock.h>
31#include <pthreaddef.h>
32#include <dl-sysdep.h>
33#include "../nptl_db/thread_db.h"
34#include <tls.h>
35#include <unwind.h>
36#define __need_res_state
37#include <resolv.h>
38#include <kernel-features.h>
39
40#ifndef TCB_ALIGNMENT
41# define TCB_ALIGNMENT sizeof (double)
42#endif
43
44
45/* We keep thread specific data in a special data structure, a two-level
46 array. The top-level array contains pointers to dynamically allocated
47 arrays of a certain number of data pointers. So we can implement a
48 sparse array. Each dynamic second-level array has
49 PTHREAD_KEY_2NDLEVEL_SIZE
50 entries. This value shouldn't be too large. */
51#define PTHREAD_KEY_2NDLEVEL_SIZE 32
52
53/* We need to address PTHREAD_KEYS_MAX key with PTHREAD_KEY_2NDLEVEL_SIZE
54 keys in each subarray. */
55#define PTHREAD_KEY_1STLEVEL_SIZE \
56 ((PTHREAD_KEYS_MAX + PTHREAD_KEY_2NDLEVEL_SIZE - 1) \
57 / PTHREAD_KEY_2NDLEVEL_SIZE)
58
59
60
61
62/* Internal version of the buffer to store cancellation handler
63 information. */
64struct pthread_unwind_buf
65{
66 struct
67 {
68 __jmp_buf jmp_buf;
69 int mask_was_saved;
70 } cancel_jmp_buf[1];
71
72 union
73 {
74 /* This is the placeholder of the public version. */
75 void *pad[4];
76
77 struct
78 {
79 /* Pointer to the previous cleanup buffer. */
80 struct pthread_unwind_buf *prev;
81
82 /* Backward compatibility: state of the old-style cleanup
83 handler at the time of the previous new-style cleanup handler
84 installment. */
85 struct _pthread_cleanup_buffer *cleanup;
86
87 /* Cancellation type before the push call. */
88 int canceltype;
89 } data;
90 } priv;
91};
92
93
94/* Opcodes and data types for communication with the signal handler to
95 change user/group IDs. */
96struct xid_command
97{
98 int syscall_no;
99 long int id[3];
100 volatile int cntr;
101 volatile int error; /* -1: no call yet, 0: success seen, >0: error seen. */
102};
103
104
105/* Data structure used by the kernel to find robust futexes. */
106struct robust_list_head
107{
108 void *list;
109 long int futex_offset;
110 void *list_op_pending;
111};
112
113
114/* Data strcture used to handle thread priority protection. */
115struct priority_protection_data
116{
117 int priomax;
118 unsigned int priomap[];
119};
120
121
122/* Thread descriptor data structure. */
123struct pthread
124{
125 union
126 {
127#if !TLS_DTV_AT_TP
128 /* This overlaps the TCB as used for TLS without threads (see tls.h). */
129 tcbhead_t header;
130#else
131 struct
132 {
133 /* multiple_threads is enabled either when the process has spawned at
134 least one thread or when a single-threaded process cancels itself.
135 This enables additional code to introduce locking before doing some
136 compare_and_exchange operations and also enable cancellation points.
137 The concepts of multiple threads and cancellation points ideally
138 should be separate, since it is not necessary for multiple threads to
139 have been created for cancellation points to be enabled, as is the
140 case is when single-threaded process cancels itself.
141
142 Since enabling multiple_threads enables additional code in
143 cancellation points and compare_and_exchange operations, there is a
144 potential for an unneeded performance hit when it is enabled in a
145 single-threaded, self-canceling process. This is OK though, since a
146 single-threaded process will enable async cancellation only when it
147 looks to cancel itself and is hence going to end anyway. */
148 int multiple_threads;
149 int gscope_flag;
150# ifndef __ASSUME_PRIVATE_FUTEX
151 int private_futex;
152# endif
153 } header;
154#endif
155
156 /* This extra padding has no special purpose, and this structure layout
157 is private and subject to change without affecting the official ABI.
158 We just have it here in case it might be convenient for some
159 implementation-specific instrumentation hack or suchlike. */
160 void *__padding[24];
161 };
162
163 /* This descriptor's link on the `stack_used' or `__stack_user' list. */
164 list_t list;
165
166 /* Thread ID - which is also a 'is this thread descriptor (and
167 therefore stack) used' flag. */
168 pid_t tid;
169
170 /* Ununsed. */
171 pid_t pid_ununsed;
172
173 /* List of robust mutexes the thread is holding. */
174#ifdef __PTHREAD_MUTEX_HAVE_PREV
175 void *robust_prev;
176 struct robust_list_head robust_head;
177
178 /* The list above is strange. It is basically a double linked list
179 but the pointer to the next/previous element of the list points
180 in the middle of the object, the __next element. Whenever
181 casting to __pthread_list_t we need to adjust the pointer
182 first.
183 These operations are effectively concurrent code in that the thread
184 can get killed at any point in time and the kernel takes over. Thus,
185 the __next elements are a kind of concurrent list and we need to
186 enforce using compiler barriers that the individual operations happen
187 in such a way that the kernel always sees a consistent list. The
188 backward links (ie, the __prev elements) are not used by the kernel.
189 FIXME We should use relaxed MO atomic operations here and signal fences
190 because this kind of concurrency is similar to synchronizing with a
191 signal handler. */
192# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
193
194# define ENQUEUE_MUTEX_BOTH(mutex, val) \
195 do { \
196 __pthread_list_t *next = (__pthread_list_t *) \
197 ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul) \
198 - QUEUE_PTR_ADJUST); \
199 next->__prev = (void *) &mutex->__data.__list.__next; \
200 mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
201 robust_head.list); \
202 mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
203 /* Ensure that the new list entry is ready before we insert it. */ \
204 __asm ("" ::: "memory"); \
205 THREAD_SETMEM (THREAD_SELF, robust_head.list, \
206 (void *) (((uintptr_t) &mutex->__data.__list.__next) \
207 | val)); \
208 } while (0)
209# define DEQUEUE_MUTEX(mutex) \
210 do { \
211 __pthread_list_t *next = (__pthread_list_t *) \
212 ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul) \
213 - QUEUE_PTR_ADJUST); \
214 next->__prev = mutex->__data.__list.__prev; \
215 __pthread_list_t *prev = (__pthread_list_t *) \
216 ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul) \
217 - QUEUE_PTR_ADJUST); \
218 prev->__next = mutex->__data.__list.__next; \
219 /* Ensure that we remove the entry from the list before we change the \
220 __next pointer of the entry, which is read by the kernel. */ \
221 __asm ("" ::: "memory"); \
222 mutex->__data.__list.__prev = NULL; \
223 mutex->__data.__list.__next = NULL; \
224 } while (0)
225#else
226 union
227 {
228 __pthread_slist_t robust_list;
229 struct robust_list_head robust_head;
230 };
231
232# define ENQUEUE_MUTEX_BOTH(mutex, val) \
233 do { \
234 mutex->__data.__list.__next \
235 = THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
236 /* Ensure that the new list entry is ready before we insert it. */ \
237 __asm ("" ::: "memory"); \
238 THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
239 (void *) (((uintptr_t) &mutex->__data.__list) | val)); \
240 } while (0)
241# define DEQUEUE_MUTEX(mutex) \
242 do { \
243 __pthread_slist_t *runp = (__pthread_slist_t *) \
244 (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
245 if (runp == &mutex->__data.__list) \
246 THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
247 else \
248 { \
249 __pthread_slist_t *next = (__pthread_slist_t *) \
250 (((uintptr_t) runp->__next) & ~1ul); \
251 while (next != &mutex->__data.__list) \
252 { \
253 runp = next; \
254 next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
255 } \
256 \
257 runp->__next = next->__next; \
258 /* Ensure that we remove the entry from the list before we change the \
259 __next pointer of the entry, which is read by the kernel. */ \
260 __asm ("" ::: "memory"); \
261 mutex->__data.__list.__next = NULL; \
262 } \
263 } while (0)
264#endif
265#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
266#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
267
268 /* List of cleanup buffers. */
269 struct _pthread_cleanup_buffer *cleanup;
270
271 /* Unwind information. */
272 struct pthread_unwind_buf *cleanup_jmp_buf;
273#define HAVE_CLEANUP_JMP_BUF
274
275 /* Flags determining processing of cancellation. */
276 int cancelhandling;
277 /* Bit set if cancellation is disabled. */
278#define CANCELSTATE_BIT 0
279#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
280 /* Bit set if asynchronous cancellation mode is selected. */
281#define CANCELTYPE_BIT 1
282#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
283 /* Bit set if canceling has been initiated. */
284#define CANCELING_BIT 2
285#define CANCELING_BITMASK (0x01 << CANCELING_BIT)
286 /* Bit set if canceled. */
287#define CANCELED_BIT 3
288#define CANCELED_BITMASK (0x01 << CANCELED_BIT)
289 /* Bit set if thread is exiting. */
290#define EXITING_BIT 4
291#define EXITING_BITMASK (0x01 << EXITING_BIT)
292 /* Bit set if thread terminated and TCB is freed. */
293#define TERMINATED_BIT 5
294#define TERMINATED_BITMASK (0x01 << TERMINATED_BIT)
295 /* Bit set if thread is supposed to change XID. */
296#define SETXID_BIT 6
297#define SETXID_BITMASK (0x01 << SETXID_BIT)
298 /* Mask for the rest. Helps the compiler to optimize. */
299#define CANCEL_RESTMASK 0xffffff80
300
301#define CANCEL_ENABLED_AND_CANCELED(value) \
302 (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
303 | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
304#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
305 (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
306 | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
307 == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
308
309 /* Flags. Including those copied from the thread attribute. */
310 int flags;
311
312 /* We allocate one block of references here. This should be enough
313 to avoid allocating any memory dynamically for most applications. */
314 struct pthread_key_data
315 {
316 /* Sequence number. We use uintptr_t to not require padding on
317 32- and 64-bit machines. On 64-bit machines it helps to avoid
318 wrapping, too. */
319 uintptr_t seq;
320
321 /* Data pointer. */
322 void *data;
323 } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
324
325 /* Two-level array for the thread-specific data. */
326 struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
327
328 /* Flag which is set when specific data is set. */
329 bool specific_used;
330
331 /* True if events must be reported. */
332 bool report_events;
333
334 /* True if the user provided the stack. */
335 bool user_stack;
336
337 /* True if thread must stop at startup time. */
338 bool stopped_start;
339
340 /* The parent's cancel handling at the time of the pthread_create
341 call. This might be needed to undo the effects of a cancellation. */
342 int parent_cancelhandling;
343
344 /* Lock to synchronize access to the descriptor. */
345 int lock;
346
347 /* Lock for synchronizing setxid calls. */
348 unsigned int setxid_futex;
349
350#if HP_TIMING_AVAIL
351 /* Offset of the CPU clock at start thread start time. */
352 hp_timing_t cpuclock_offset;
353#endif
354
355 /* If the thread waits to join another one the ID of the latter is
356 stored here.
357
358 In case a thread is detached this field contains a pointer of the
359 TCB if the thread itself. This is something which cannot happen
360 in normal operation. */
361 struct pthread *joinid;
362 /* Check whether a thread is detached. */
363#define IS_DETACHED(pd) ((pd)->joinid == (pd))
364
365 /* The result of the thread function. */
366 void *result;
367
368 /* Scheduling parameters for the new thread. */
369 struct sched_param schedparam;
370 int schedpolicy;
371
372 /* Start position of the code to be executed and the argument passed
373 to the function. */
374 void *(*start_routine) (void *);
375 void *arg;
376
377 /* Debug state. */
378 td_eventbuf_t eventbuf;
379 /* Next descriptor with a pending event. */
380 struct pthread *nextevent;
381
382 /* Machine-specific unwind info. */
383 struct _Unwind_Exception exc;
384
385 /* If nonzero pointer to area allocated for the stack and its
386 size. */
387 void *stackblock;
388 size_t stackblock_size;
389 /* Size of the included guard area. */
390 size_t guardsize;
391 /* This is what the user specified and what we will report. */
392 size_t reported_guardsize;
393
394 /* Thread Priority Protection data. */
395 struct priority_protection_data *tpp;
396
397 /* Resolver state. */
398 struct __res_state res;
399
400 /* This member must be last. */
401 char end_padding[];
402
403#define PTHREAD_STRUCT_END_PADDING \
404 (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
405} __attribute ((aligned (TCB_ALIGNMENT)));
406
407
408#endif /* descr.h */
409