1/* Copyright (C) 2002-2020 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 <https://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#include <list_t.h>
29#include <lowlevellock.h>
30#include <pthreaddef.h>
31#include <dl-sysdep.h>
32#include <thread_db.h>
33#include <tls.h>
34#include <unwind.h>
35#include <bits/types/res_state.h>
36#include <kernel-features.h>
37#include <tls-internal-struct.h>
38
39#ifndef TCB_ALIGNMENT
40# define TCB_ALIGNMENT sizeof (double)
41#endif
42
43
44/* We keep thread specific data in a special data structure, a two-level
45 array. The top-level array contains pointers to dynamically allocated
46 arrays of a certain number of data pointers. So we can implement a
47 sparse array. Each dynamic second-level array has
48 PTHREAD_KEY_2NDLEVEL_SIZE
49 entries. This value shouldn't be too large. */
50#define PTHREAD_KEY_2NDLEVEL_SIZE 32
51
52/* We need to address PTHREAD_KEYS_MAX key with PTHREAD_KEY_2NDLEVEL_SIZE
53 keys in each subarray. */
54#define PTHREAD_KEY_1STLEVEL_SIZE \
55 ((PTHREAD_KEYS_MAX + PTHREAD_KEY_2NDLEVEL_SIZE - 1) \
56 / PTHREAD_KEY_2NDLEVEL_SIZE)
57
58
59
60
61/* Internal version of the buffer to store cancellation handler
62 information. */
63struct pthread_unwind_buf
64{
65 struct
66 {
67 __jmp_buf jmp_buf;
68 int mask_was_saved;
69 } cancel_jmp_buf[1];
70
71 union
72 {
73 /* This is the placeholder of the public version. */
74 void *pad[4];
75
76 struct
77 {
78 /* Pointer to the previous cleanup buffer. */
79 struct pthread_unwind_buf *prev;
80
81 /* Backward compatibility: state of the old-style cleanup
82 handler at the time of the previous new-style cleanup handler
83 installment. */
84 struct _pthread_cleanup_buffer *cleanup;
85
86 /* Cancellation type before the push call. */
87 int canceltype;
88 } data;
89 } priv;
90};
91
92
93/* Opcodes and data types for communication with the signal handler to
94 change user/group IDs. */
95struct xid_command
96{
97 int syscall_no;
98 /* Enforce zero-extension for the pointer argument in
99
100 int setgroups (size_t size, const gid_t *list);
101
102 The kernel XID arguments are unsigned and do not require sign
103 extension. */
104 unsigned long int id[3];
105 volatile int cntr;
106 volatile int error; /* -1: no call yet, 0: success seen, >0: error seen. */
107};
108
109
110/* Data structure used by the kernel to find robust futexes. */
111struct robust_list_head
112{
113 void *list;
114 long int futex_offset;
115 void *list_op_pending;
116};
117
118
119/* Data strcture used to handle thread priority protection. */
120struct priority_protection_data
121{
122 int priomax;
123 unsigned int priomap[];
124};
125
126
127/* Thread descriptor data structure. */
128struct pthread
129{
130 union
131 {
132#if !TLS_DTV_AT_TP
133 /* This overlaps the TCB as used for TLS without threads (see tls.h). */
134 tcbhead_t header;
135#else
136 struct
137 {
138 /* multiple_threads is enabled either when the process has spawned at
139 least one thread or when a single-threaded process cancels itself.
140 This enables additional code to introduce locking before doing some
141 compare_and_exchange operations and also enable cancellation points.
142 The concepts of multiple threads and cancellation points ideally
143 should be separate, since it is not necessary for multiple threads to
144 have been created for cancellation points to be enabled, as is the
145 case is when single-threaded process cancels itself.
146
147 Since enabling multiple_threads enables additional code in
148 cancellation points and compare_and_exchange operations, there is a
149 potential for an unneeded performance hit when it is enabled in a
150 single-threaded, self-canceling process. This is OK though, since a
151 single-threaded process will enable async cancellation only when it
152 looks to cancel itself and is hence going to end anyway. */
153 int multiple_threads;
154 int gscope_flag;
155 } header;
156#endif
157
158 /* This extra padding has no special purpose, and this structure layout
159 is private and subject to change without affecting the official ABI.
160 We just have it here in case it might be convenient for some
161 implementation-specific instrumentation hack or suchlike. */
162 void *__padding[24];
163 };
164
165 /* This descriptor's link on the `stack_used' or `__stack_user' list. */
166 list_t list;
167
168 /* Thread ID - which is also a 'is this thread descriptor (and
169 therefore stack) used' flag. */
170 pid_t tid;
171
172 /* Ununsed. */
173 pid_t pid_ununsed;
174
175 /* List of robust mutexes the thread is holding. */
176#if __PTHREAD_MUTEX_HAVE_PREV
177 void *robust_prev;
178 struct robust_list_head robust_head;
179
180 /* The list above is strange. It is basically a double linked list
181 but the pointer to the next/previous element of the list points
182 in the middle of the object, the __next element. Whenever
183 casting to __pthread_list_t we need to adjust the pointer
184 first.
185 These operations are effectively concurrent code in that the thread
186 can get killed at any point in time and the kernel takes over. Thus,
187 the __next elements are a kind of concurrent list and we need to
188 enforce using compiler barriers that the individual operations happen
189 in such a way that the kernel always sees a consistent list. The
190 backward links (ie, the __prev elements) are not used by the kernel.
191 FIXME We should use relaxed MO atomic operations here and signal fences
192 because this kind of concurrency is similar to synchronizing with a
193 signal handler. */
194# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
195
196# define ENQUEUE_MUTEX_BOTH(mutex, val) \
197 do { \
198 __pthread_list_t *next = (__pthread_list_t *) \
199 ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul) \
200 - QUEUE_PTR_ADJUST); \
201 next->__prev = (void *) &mutex->__data.__list.__next; \
202 mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
203 robust_head.list); \
204 mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
205 /* Ensure that the new list entry is ready before we insert it. */ \
206 __asm ("" ::: "memory"); \
207 THREAD_SETMEM (THREAD_SELF, robust_head.list, \
208 (void *) (((uintptr_t) &mutex->__data.__list.__next) \
209 | val)); \
210 } while (0)
211# define DEQUEUE_MUTEX(mutex) \
212 do { \
213 __pthread_list_t *next = (__pthread_list_t *) \
214 ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul) \
215 - QUEUE_PTR_ADJUST); \
216 next->__prev = mutex->__data.__list.__prev; \
217 __pthread_list_t *prev = (__pthread_list_t *) \
218 ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul) \
219 - QUEUE_PTR_ADJUST); \
220 prev->__next = mutex->__data.__list.__next; \
221 /* Ensure that we remove the entry from the list before we change the \
222 __next pointer of the entry, which is read by the kernel. */ \
223 __asm ("" ::: "memory"); \
224 mutex->__data.__list.__prev = NULL; \
225 mutex->__data.__list.__next = NULL; \
226 } while (0)
227#else
228 union
229 {
230 __pthread_slist_t robust_list;
231 struct robust_list_head robust_head;
232 };
233
234# define ENQUEUE_MUTEX_BOTH(mutex, val) \
235 do { \
236 mutex->__data.__list.__next \
237 = THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
238 /* Ensure that the new list entry is ready before we insert it. */ \
239 __asm ("" ::: "memory"); \
240 THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
241 (void *) (((uintptr_t) &mutex->__data.__list) | val)); \
242 } while (0)
243# define DEQUEUE_MUTEX(mutex) \
244 do { \
245 __pthread_slist_t *runp = (__pthread_slist_t *) \
246 (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
247 if (runp == &mutex->__data.__list) \
248 THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
249 else \
250 { \
251 __pthread_slist_t *next = (__pthread_slist_t *) \
252 (((uintptr_t) runp->__next) & ~1ul); \
253 while (next != &mutex->__data.__list) \
254 { \
255 runp = next; \
256 next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
257 } \
258 \
259 runp->__next = next->__next; \
260 /* Ensure that we remove the entry from the list before we change the \
261 __next pointer of the entry, which is read by the kernel. */ \
262 __asm ("" ::: "memory"); \
263 mutex->__data.__list.__next = NULL; \
264 } \
265 } while (0)
266#endif
267#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
268#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
269
270 /* List of cleanup buffers. */
271 struct _pthread_cleanup_buffer *cleanup;
272
273 /* Unwind information. */
274 struct pthread_unwind_buf *cleanup_jmp_buf;
275#define HAVE_CLEANUP_JMP_BUF
276
277 /* Flags determining processing of cancellation. */
278 int cancelhandling;
279 /* Bit set if cancellation is disabled. */
280#define CANCELSTATE_BIT 0
281#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
282 /* Bit set if asynchronous cancellation mode is selected. */
283#define CANCELTYPE_BIT 1
284#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
285 /* Bit set if canceling has been initiated. */
286#define CANCELING_BIT 2
287#define CANCELING_BITMASK (0x01 << CANCELING_BIT)
288 /* Bit set if canceled. */
289#define CANCELED_BIT 3
290#define CANCELED_BITMASK (0x01 << CANCELED_BIT)
291 /* Bit set if thread is exiting. */
292#define EXITING_BIT 4
293#define EXITING_BITMASK (0x01 << EXITING_BIT)
294 /* Bit set if thread terminated and TCB is freed. */
295#define TERMINATED_BIT 5
296#define TERMINATED_BITMASK (0x01 << TERMINATED_BIT)
297 /* Bit set if thread is supposed to change XID. */
298#define SETXID_BIT 6
299#define SETXID_BITMASK (0x01 << SETXID_BIT)
300 /* Mask for the rest. Helps the compiler to optimize. */
301#define CANCEL_RESTMASK 0xffffff80
302
303#define CANCEL_ENABLED_AND_CANCELED(value) \
304 (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
305 | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
306#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
307 (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
308 | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
309 == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
310
311 /* Flags. Including those copied from the thread attribute. */
312 int flags;
313
314 /* We allocate one block of references here. This should be enough
315 to avoid allocating any memory dynamically for most applications. */
316 struct pthread_key_data
317 {
318 /* Sequence number. We use uintptr_t to not require padding on
319 32- and 64-bit machines. On 64-bit machines it helps to avoid
320 wrapping, too. */
321 uintptr_t seq;
322
323 /* Data pointer. */
324 void *data;
325 } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
326
327 /* Two-level array for the thread-specific data. */
328 struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
329
330 /* Flag which is set when specific data is set. */
331 bool specific_used;
332
333 /* True if events must be reported. */
334 bool report_events;
335
336 /* True if the user provided the stack. */
337 bool user_stack;
338
339 /* True if thread must stop at startup time. */
340 bool stopped_start;
341
342 /* Formerly used for dealing with cancellation. */
343 int parent_cancelhandling_unsed;
344
345 /* Lock to synchronize access to the descriptor. */
346 int lock;
347
348 /* Lock for synchronizing setxid calls. */
349 unsigned int setxid_futex;
350
351#if HP_TIMING_INLINE
352 hp_timing_t cpuclock_offset_ununsed;
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 the area allocated for the stack and guard. */
386 void *stackblock;
387 /* Size of the stackblock area including the guard. */
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 /* Signal mask for the new thread. Used during thread startup to
401 restore the signal mask. (Threads are launched with all signals
402 masked.) */
403 sigset_t sigmask;
404
405 /* Indicates whether is a C11 thread created by thrd_creat. */
406 bool c11;
407
408 /* Used on strsignal. */
409 struct tls_internal_t tls_state;
410
411 /* This member must be last. */
412 char end_padding[];
413
414#define PTHREAD_STRUCT_END_PADDING \
415 (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
416} __attribute ((aligned (TCB_ALIGNMENT)));
417
418
419#endif /* descr.h */
420