1/* Copyright (C) 2002-2019 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#include <list_t.h>
29#include <lowlevellock.h>
30#include <pthreaddef.h>
31#include <dl-sysdep.h>
32#include "../nptl_db/thread_db.h"
33#include <tls.h>
34#include <unwind.h>
35#include <bits/types/res_state.h>
36#include <kernel-features.h>
37
38#ifndef TCB_ALIGNMENT
39# define TCB_ALIGNMENT sizeof (double)
40#endif
41
42
43/* We keep thread specific data in a special data structure, a two-level
44 array. The top-level array contains pointers to dynamically allocated
45 arrays of a certain number of data pointers. So we can implement a
46 sparse array. Each dynamic second-level array has
47 PTHREAD_KEY_2NDLEVEL_SIZE
48 entries. This value shouldn't be too large. */
49#define PTHREAD_KEY_2NDLEVEL_SIZE 32
50
51/* We need to address PTHREAD_KEYS_MAX key with PTHREAD_KEY_2NDLEVEL_SIZE
52 keys in each subarray. */
53#define PTHREAD_KEY_1STLEVEL_SIZE \
54 ((PTHREAD_KEYS_MAX + PTHREAD_KEY_2NDLEVEL_SIZE - 1) \
55 / PTHREAD_KEY_2NDLEVEL_SIZE)
56
57
58
59
60/* Internal version of the buffer to store cancellation handler
61 information. */
62struct pthread_unwind_buf
63{
64 struct
65 {
66 __jmp_buf jmp_buf;
67 int mask_was_saved;
68 } cancel_jmp_buf[1];
69
70 union
71 {
72 /* This is the placeholder of the public version. */
73 void *pad[4];
74
75 struct
76 {
77 /* Pointer to the previous cleanup buffer. */
78 struct pthread_unwind_buf *prev;
79
80 /* Backward compatibility: state of the old-style cleanup
81 handler at the time of the previous new-style cleanup handler
82 installment. */
83 struct _pthread_cleanup_buffer *cleanup;
84
85 /* Cancellation type before the push call. */
86 int canceltype;
87 } data;
88 } priv;
89};
90
91
92/* Opcodes and data types for communication with the signal handler to
93 change user/group IDs. */
94struct xid_command
95{
96 int syscall_no;
97 long int id[3];
98 volatile int cntr;
99 volatile int error; /* -1: no call yet, 0: success seen, >0: error seen. */
100};
101
102
103/* Data structure used by the kernel to find robust futexes. */
104struct robust_list_head
105{
106 void *list;
107 long int futex_offset;
108 void *list_op_pending;
109};
110
111
112/* Data strcture used to handle thread priority protection. */
113struct priority_protection_data
114{
115 int priomax;
116 unsigned int priomap[];
117};
118
119
120/* Thread descriptor data structure. */
121struct pthread
122{
123 union
124 {
125#if !TLS_DTV_AT_TP
126 /* This overlaps the TCB as used for TLS without threads (see tls.h). */
127 tcbhead_t header;
128#else
129 struct
130 {
131 /* multiple_threads is enabled either when the process has spawned at
132 least one thread or when a single-threaded process cancels itself.
133 This enables additional code to introduce locking before doing some
134 compare_and_exchange operations and also enable cancellation points.
135 The concepts of multiple threads and cancellation points ideally
136 should be separate, since it is not necessary for multiple threads to
137 have been created for cancellation points to be enabled, as is the
138 case is when single-threaded process cancels itself.
139
140 Since enabling multiple_threads enables additional code in
141 cancellation points and compare_and_exchange operations, there is a
142 potential for an unneeded performance hit when it is enabled in a
143 single-threaded, self-canceling process. This is OK though, since a
144 single-threaded process will enable async cancellation only when it
145 looks to cancel itself and is hence going to end anyway. */
146 int multiple_threads;
147 int gscope_flag;
148 } header;
149#endif
150
151 /* This extra padding has no special purpose, and this structure layout
152 is private and subject to change without affecting the official ABI.
153 We just have it here in case it might be convenient for some
154 implementation-specific instrumentation hack or suchlike. */
155 void *__padding[24];
156 };
157
158 /* This descriptor's link on the `stack_used' or `__stack_user' list. */
159 list_t list;
160
161 /* Thread ID - which is also a 'is this thread descriptor (and
162 therefore stack) used' flag. */
163 pid_t tid;
164
165 /* Ununsed. */
166 pid_t pid_ununsed;
167
168 /* List of robust mutexes the thread is holding. */
169#if __PTHREAD_MUTEX_HAVE_PREV
170 void *robust_prev;
171 struct robust_list_head robust_head;
172
173 /* The list above is strange. It is basically a double linked list
174 but the pointer to the next/previous element of the list points
175 in the middle of the object, the __next element. Whenever
176 casting to __pthread_list_t we need to adjust the pointer
177 first.
178 These operations are effectively concurrent code in that the thread
179 can get killed at any point in time and the kernel takes over. Thus,
180 the __next elements are a kind of concurrent list and we need to
181 enforce using compiler barriers that the individual operations happen
182 in such a way that the kernel always sees a consistent list. The
183 backward links (ie, the __prev elements) are not used by the kernel.
184 FIXME We should use relaxed MO atomic operations here and signal fences
185 because this kind of concurrency is similar to synchronizing with a
186 signal handler. */
187# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
188
189# define ENQUEUE_MUTEX_BOTH(mutex, val) \
190 do { \
191 __pthread_list_t *next = (__pthread_list_t *) \
192 ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul) \
193 - QUEUE_PTR_ADJUST); \
194 next->__prev = (void *) &mutex->__data.__list.__next; \
195 mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
196 robust_head.list); \
197 mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
198 /* Ensure that the new list entry is ready before we insert it. */ \
199 __asm ("" ::: "memory"); \
200 THREAD_SETMEM (THREAD_SELF, robust_head.list, \
201 (void *) (((uintptr_t) &mutex->__data.__list.__next) \
202 | val)); \
203 } while (0)
204# define DEQUEUE_MUTEX(mutex) \
205 do { \
206 __pthread_list_t *next = (__pthread_list_t *) \
207 ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul) \
208 - QUEUE_PTR_ADJUST); \
209 next->__prev = mutex->__data.__list.__prev; \
210 __pthread_list_t *prev = (__pthread_list_t *) \
211 ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul) \
212 - QUEUE_PTR_ADJUST); \
213 prev->__next = mutex->__data.__list.__next; \
214 /* Ensure that we remove the entry from the list before we change the \
215 __next pointer of the entry, which is read by the kernel. */ \
216 __asm ("" ::: "memory"); \
217 mutex->__data.__list.__prev = NULL; \
218 mutex->__data.__list.__next = NULL; \
219 } while (0)
220#else
221 union
222 {
223 __pthread_slist_t robust_list;
224 struct robust_list_head robust_head;
225 };
226
227# define ENQUEUE_MUTEX_BOTH(mutex, val) \
228 do { \
229 mutex->__data.__list.__next \
230 = THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
231 /* Ensure that the new list entry is ready before we insert it. */ \
232 __asm ("" ::: "memory"); \
233 THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
234 (void *) (((uintptr_t) &mutex->__data.__list) | val)); \
235 } while (0)
236# define DEQUEUE_MUTEX(mutex) \
237 do { \
238 __pthread_slist_t *runp = (__pthread_slist_t *) \
239 (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
240 if (runp == &mutex->__data.__list) \
241 THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
242 else \
243 { \
244 __pthread_slist_t *next = (__pthread_slist_t *) \
245 (((uintptr_t) runp->__next) & ~1ul); \
246 while (next != &mutex->__data.__list) \
247 { \
248 runp = next; \
249 next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
250 } \
251 \
252 runp->__next = next->__next; \
253 /* Ensure that we remove the entry from the list before we change the \
254 __next pointer of the entry, which is read by the kernel. */ \
255 __asm ("" ::: "memory"); \
256 mutex->__data.__list.__next = NULL; \
257 } \
258 } while (0)
259#endif
260#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
261#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
262
263 /* List of cleanup buffers. */
264 struct _pthread_cleanup_buffer *cleanup;
265
266 /* Unwind information. */
267 struct pthread_unwind_buf *cleanup_jmp_buf;
268#define HAVE_CLEANUP_JMP_BUF
269
270 /* Flags determining processing of cancellation. */
271 int cancelhandling;
272 /* Bit set if cancellation is disabled. */
273#define CANCELSTATE_BIT 0
274#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
275 /* Bit set if asynchronous cancellation mode is selected. */
276#define CANCELTYPE_BIT 1
277#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
278 /* Bit set if canceling has been initiated. */
279#define CANCELING_BIT 2
280#define CANCELING_BITMASK (0x01 << CANCELING_BIT)
281 /* Bit set if canceled. */
282#define CANCELED_BIT 3
283#define CANCELED_BITMASK (0x01 << CANCELED_BIT)
284 /* Bit set if thread is exiting. */
285#define EXITING_BIT 4
286#define EXITING_BITMASK (0x01 << EXITING_BIT)
287 /* Bit set if thread terminated and TCB is freed. */
288#define TERMINATED_BIT 5
289#define TERMINATED_BITMASK (0x01 << TERMINATED_BIT)
290 /* Bit set if thread is supposed to change XID. */
291#define SETXID_BIT 6
292#define SETXID_BITMASK (0x01 << SETXID_BIT)
293 /* Mask for the rest. Helps the compiler to optimize. */
294#define CANCEL_RESTMASK 0xffffff80
295
296#define CANCEL_ENABLED_AND_CANCELED(value) \
297 (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
298 | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
299#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
300 (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
301 | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
302 == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
303
304 /* Flags. Including those copied from the thread attribute. */
305 int flags;
306
307 /* We allocate one block of references here. This should be enough
308 to avoid allocating any memory dynamically for most applications. */
309 struct pthread_key_data
310 {
311 /* Sequence number. We use uintptr_t to not require padding on
312 32- and 64-bit machines. On 64-bit machines it helps to avoid
313 wrapping, too. */
314 uintptr_t seq;
315
316 /* Data pointer. */
317 void *data;
318 } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
319
320 /* Two-level array for the thread-specific data. */
321 struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
322
323 /* Flag which is set when specific data is set. */
324 bool specific_used;
325
326 /* True if events must be reported. */
327 bool report_events;
328
329 /* True if the user provided the stack. */
330 bool user_stack;
331
332 /* True if thread must stop at startup time. */
333 bool stopped_start;
334
335 /* The parent's cancel handling at the time of the pthread_create
336 call. This might be needed to undo the effects of a cancellation. */
337 int parent_cancelhandling;
338
339 /* Lock to synchronize access to the descriptor. */
340 int lock;
341
342 /* Lock for synchronizing setxid calls. */
343 unsigned int setxid_futex;
344
345#if HP_TIMING_AVAIL
346 /* Offset of the CPU clock at start thread start time. */
347 hp_timing_t cpuclock_offset;
348#endif
349
350 /* If the thread waits to join another one the ID of the latter is
351 stored here.
352
353 In case a thread is detached this field contains a pointer of the
354 TCB if the thread itself. This is something which cannot happen
355 in normal operation. */
356 struct pthread *joinid;
357 /* Check whether a thread is detached. */
358#define IS_DETACHED(pd) ((pd)->joinid == (pd))
359
360 /* The result of the thread function. */
361 void *result;
362
363 /* Scheduling parameters for the new thread. */
364 struct sched_param schedparam;
365 int schedpolicy;
366
367 /* Start position of the code to be executed and the argument passed
368 to the function. */
369 void *(*start_routine) (void *);
370 void *arg;
371
372 /* Debug state. */
373 td_eventbuf_t eventbuf;
374 /* Next descriptor with a pending event. */
375 struct pthread *nextevent;
376
377 /* Machine-specific unwind info. */
378 struct _Unwind_Exception exc;
379
380 /* If nonzero, pointer to the area allocated for the stack and guard. */
381 void *stackblock;
382 /* Size of the stackblock area including the guard. */
383 size_t stackblock_size;
384 /* Size of the included guard area. */
385 size_t guardsize;
386 /* This is what the user specified and what we will report. */
387 size_t reported_guardsize;
388
389 /* Thread Priority Protection data. */
390 struct priority_protection_data *tpp;
391
392 /* Resolver state. */
393 struct __res_state res;
394
395 /* Indicates whether is a C11 thread created by thrd_creat. */
396 bool c11;
397
398 /* This member must be last. */
399 char end_padding[];
400
401#define PTHREAD_STRUCT_END_PADDING \
402 (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
403} __attribute ((aligned (TCB_ALIGNMENT)));
404
405
406#endif /* descr.h */
407