1/* Copyright (C) 2002-2021 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 GL (dl_stack_used) or
166 GL (dl_stack_user) list. */
167 list_t list;
168
169 /* Thread ID - which is also a 'is this thread descriptor (and
170 therefore stack) used' flag. */
171 pid_t tid;
172
173 /* Ununsed. */
174 pid_t pid_ununsed;
175
176 /* List of robust mutexes the thread is holding. */
177#if __PTHREAD_MUTEX_HAVE_PREV
178 void *robust_prev;
179 struct robust_list_head robust_head;
180
181 /* The list above is strange. It is basically a double linked list
182 but the pointer to the next/previous element of the list points
183 in the middle of the object, the __next element. Whenever
184 casting to __pthread_list_t we need to adjust the pointer
185 first.
186 These operations are effectively concurrent code in that the thread
187 can get killed at any point in time and the kernel takes over. Thus,
188 the __next elements are a kind of concurrent list and we need to
189 enforce using compiler barriers that the individual operations happen
190 in such a way that the kernel always sees a consistent list. The
191 backward links (ie, the __prev elements) are not used by the kernel.
192 FIXME We should use relaxed MO atomic operations here and signal fences
193 because this kind of concurrency is similar to synchronizing with a
194 signal handler. */
195# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
196
197# define ENQUEUE_MUTEX_BOTH(mutex, val) \
198 do { \
199 __pthread_list_t *next = (__pthread_list_t *) \
200 ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul) \
201 - QUEUE_PTR_ADJUST); \
202 next->__prev = (void *) &mutex->__data.__list.__next; \
203 mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
204 robust_head.list); \
205 mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
206 /* Ensure that the new list entry is ready before we insert it. */ \
207 __asm ("" ::: "memory"); \
208 THREAD_SETMEM (THREAD_SELF, robust_head.list, \
209 (void *) (((uintptr_t) &mutex->__data.__list.__next) \
210 | val)); \
211 } while (0)
212# define DEQUEUE_MUTEX(mutex) \
213 do { \
214 __pthread_list_t *next = (__pthread_list_t *) \
215 ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul) \
216 - QUEUE_PTR_ADJUST); \
217 next->__prev = mutex->__data.__list.__prev; \
218 __pthread_list_t *prev = (__pthread_list_t *) \
219 ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul) \
220 - QUEUE_PTR_ADJUST); \
221 prev->__next = mutex->__data.__list.__next; \
222 /* Ensure that we remove the entry from the list before we change the \
223 __next pointer of the entry, which is read by the kernel. */ \
224 __asm ("" ::: "memory"); \
225 mutex->__data.__list.__prev = NULL; \
226 mutex->__data.__list.__next = NULL; \
227 } while (0)
228#else
229 union
230 {
231 __pthread_slist_t robust_list;
232 struct robust_list_head robust_head;
233 };
234
235# define ENQUEUE_MUTEX_BOTH(mutex, val) \
236 do { \
237 mutex->__data.__list.__next \
238 = THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
239 /* Ensure that the new list entry is ready before we insert it. */ \
240 __asm ("" ::: "memory"); \
241 THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
242 (void *) (((uintptr_t) &mutex->__data.__list) | val)); \
243 } while (0)
244# define DEQUEUE_MUTEX(mutex) \
245 do { \
246 __pthread_slist_t *runp = (__pthread_slist_t *) \
247 (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
248 if (runp == &mutex->__data.__list) \
249 THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
250 else \
251 { \
252 __pthread_slist_t *next = (__pthread_slist_t *) \
253 (((uintptr_t) runp->__next) & ~1ul); \
254 while (next != &mutex->__data.__list) \
255 { \
256 runp = next; \
257 next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
258 } \
259 \
260 runp->__next = next->__next; \
261 /* Ensure that we remove the entry from the list before we change the \
262 __next pointer of the entry, which is read by the kernel. */ \
263 __asm ("" ::: "memory"); \
264 mutex->__data.__list.__next = NULL; \
265 } \
266 } while (0)
267#endif
268#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
269#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
270
271 /* List of cleanup buffers. */
272 struct _pthread_cleanup_buffer *cleanup;
273
274 /* Unwind information. */
275 struct pthread_unwind_buf *cleanup_jmp_buf;
276#define HAVE_CLEANUP_JMP_BUF
277
278 /* Flags determining processing of cancellation. */
279 int cancelhandling;
280 /* Bit set if cancellation is disabled. */
281#define CANCELSTATE_BIT 0
282#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
283 /* Bit set if asynchronous cancellation mode is selected. */
284#define CANCELTYPE_BIT 1
285#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
286 /* Bit set if canceling has been initiated. */
287#define CANCELING_BIT 2
288#define CANCELING_BITMASK (0x01 << CANCELING_BIT)
289 /* Bit set if canceled. */
290#define CANCELED_BIT 3
291#define CANCELED_BITMASK (0x01 << CANCELED_BIT)
292 /* Bit set if thread is exiting. */
293#define EXITING_BIT 4
294#define EXITING_BITMASK (0x01 << EXITING_BIT)
295 /* Bit set if thread terminated and TCB is freed. */
296#define TERMINATED_BIT 5
297#define TERMINATED_BITMASK (0x01 << TERMINATED_BIT)
298 /* Bit set if thread is supposed to change XID. */
299#define SETXID_BIT 6
300#define SETXID_BITMASK (0x01 << SETXID_BIT)
301 /* Mask for the rest. Helps the compiler to optimize. */
302#define CANCEL_RESTMASK 0xffffff80
303
304#define CANCEL_ENABLED_AND_CANCELED(value) \
305 (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
306 | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
307#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
308 (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
309 | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
310 == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
311
312 /* Flags. Including those copied from the thread attribute. */
313 int flags;
314
315 /* We allocate one block of references here. This should be enough
316 to avoid allocating any memory dynamically for most applications. */
317 struct pthread_key_data
318 {
319 /* Sequence number. We use uintptr_t to not require padding on
320 32- and 64-bit machines. On 64-bit machines it helps to avoid
321 wrapping, too. */
322 uintptr_t seq;
323
324 /* Data pointer. */
325 void *data;
326 } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
327
328 /* Two-level array for the thread-specific data. */
329 struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
330
331 /* Flag which is set when specific data is set. */
332 bool specific_used;
333
334 /* True if events must be reported. */
335 bool report_events;
336
337 /* True if the user provided the stack. */
338 bool user_stack;
339
340 /* True if thread must stop at startup time. */
341 bool stopped_start;
342
343 /* Formerly used for dealing with cancellation. */
344 int parent_cancelhandling_unsed;
345
346 /* Lock to synchronize access to the descriptor. */
347 int lock;
348
349 /* Lock for synchronizing setxid calls. */
350 unsigned int setxid_futex;
351
352#if HP_TIMING_INLINE
353 hp_timing_t cpuclock_offset_ununsed;
354#endif
355
356 /* If the thread waits to join another one the ID of the latter is
357 stored here.
358
359 In case a thread is detached this field contains a pointer of the
360 TCB if the thread itself. This is something which cannot happen
361 in normal operation. */
362 struct pthread *joinid;
363 /* Check whether a thread is detached. */
364#define IS_DETACHED(pd) ((pd)->joinid == (pd))
365
366 /* The result of the thread function. */
367 void *result;
368
369 /* Scheduling parameters for the new thread. */
370 struct sched_param schedparam;
371 int schedpolicy;
372
373 /* Start position of the code to be executed and the argument passed
374 to the function. */
375 void *(*start_routine) (void *);
376 void *arg;
377
378 /* Debug state. */
379 td_eventbuf_t eventbuf;
380 /* Next descriptor with a pending event. */
381 struct pthread *nextevent;
382
383 /* Machine-specific unwind info. */
384 struct _Unwind_Exception exc;
385
386 /* If nonzero, pointer to the area allocated for the stack and guard. */
387 void *stackblock;
388 /* Size of the stackblock area including the guard. */
389 size_t stackblock_size;
390 /* Size of the included guard area. */
391 size_t guardsize;
392 /* This is what the user specified and what we will report. */
393 size_t reported_guardsize;
394
395 /* Thread Priority Protection data. */
396 struct priority_protection_data *tpp;
397
398 /* Resolver state. */
399 struct __res_state res;
400
401 /* Signal mask for the new thread. Used during thread startup to
402 restore the signal mask. (Threads are launched with all signals
403 masked.) */
404 sigset_t sigmask;
405
406 /* Indicates whether is a C11 thread created by thrd_creat. */
407 bool c11;
408
409 /* Used on strsignal. */
410 struct tls_internal_t tls_state;
411
412 /* This member must be last. */
413 char end_padding[];
414
415#define PTHREAD_STRUCT_END_PADDING \
416 (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
417} __attribute ((aligned (TCB_ALIGNMENT)));
418
419
420#endif /* descr.h */
421