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#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# ifndef __ASSUME_PRIVATE_FUTEX
149 int private_futex;
150# endif
151 } header;
152#endif
153
154 /* This extra padding has no special purpose, and this structure layout
155 is private and subject to change without affecting the official ABI.
156 We just have it here in case it might be convenient for some
157 implementation-specific instrumentation hack or suchlike. */
158 void *__padding[24];
159 };
160
161 /* This descriptor's link on the `stack_used' or `__stack_user' list. */
162 list_t list;
163
164 /* Thread ID - which is also a 'is this thread descriptor (and
165 therefore stack) used' flag. */
166 pid_t tid;
167
168 /* Ununsed. */
169 pid_t pid_ununsed;
170
171 /* List of robust mutexes the thread is holding. */
172#ifdef __PTHREAD_MUTEX_HAVE_PREV
173 void *robust_prev;
174 struct robust_list_head robust_head;
175
176 /* The list above is strange. It is basically a double linked list
177 but the pointer to the next/previous element of the list points
178 in the middle of the object, the __next element. Whenever
179 casting to __pthread_list_t we need to adjust the pointer
180 first.
181 These operations are effectively concurrent code in that the thread
182 can get killed at any point in time and the kernel takes over. Thus,
183 the __next elements are a kind of concurrent list and we need to
184 enforce using compiler barriers that the individual operations happen
185 in such a way that the kernel always sees a consistent list. The
186 backward links (ie, the __prev elements) are not used by the kernel.
187 FIXME We should use relaxed MO atomic operations here and signal fences
188 because this kind of concurrency is similar to synchronizing with a
189 signal handler. */
190# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
191
192# define ENQUEUE_MUTEX_BOTH(mutex, val) \
193 do { \
194 __pthread_list_t *next = (__pthread_list_t *) \
195 ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul) \
196 - QUEUE_PTR_ADJUST); \
197 next->__prev = (void *) &mutex->__data.__list.__next; \
198 mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
199 robust_head.list); \
200 mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
201 /* Ensure that the new list entry is ready before we insert it. */ \
202 __asm ("" ::: "memory"); \
203 THREAD_SETMEM (THREAD_SELF, robust_head.list, \
204 (void *) (((uintptr_t) &mutex->__data.__list.__next) \
205 | val)); \
206 } while (0)
207# define DEQUEUE_MUTEX(mutex) \
208 do { \
209 __pthread_list_t *next = (__pthread_list_t *) \
210 ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul) \
211 - QUEUE_PTR_ADJUST); \
212 next->__prev = mutex->__data.__list.__prev; \
213 __pthread_list_t *prev = (__pthread_list_t *) \
214 ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul) \
215 - QUEUE_PTR_ADJUST); \
216 prev->__next = mutex->__data.__list.__next; \
217 /* Ensure that we remove the entry from the list before we change the \
218 __next pointer of the entry, which is read by the kernel. */ \
219 __asm ("" ::: "memory"); \
220 mutex->__data.__list.__prev = NULL; \
221 mutex->__data.__list.__next = NULL; \
222 } while (0)
223#else
224 union
225 {
226 __pthread_slist_t robust_list;
227 struct robust_list_head robust_head;
228 };
229
230# define ENQUEUE_MUTEX_BOTH(mutex, val) \
231 do { \
232 mutex->__data.__list.__next \
233 = THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
234 /* Ensure that the new list entry is ready before we insert it. */ \
235 __asm ("" ::: "memory"); \
236 THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
237 (void *) (((uintptr_t) &mutex->__data.__list) | val)); \
238 } while (0)
239# define DEQUEUE_MUTEX(mutex) \
240 do { \
241 __pthread_slist_t *runp = (__pthread_slist_t *) \
242 (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
243 if (runp == &mutex->__data.__list) \
244 THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
245 else \
246 { \
247 __pthread_slist_t *next = (__pthread_slist_t *) \
248 (((uintptr_t) runp->__next) & ~1ul); \
249 while (next != &mutex->__data.__list) \
250 { \
251 runp = next; \
252 next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
253 } \
254 \
255 runp->__next = next->__next; \
256 /* Ensure that we remove the entry from the list before we change the \
257 __next pointer of the entry, which is read by the kernel. */ \
258 __asm ("" ::: "memory"); \
259 mutex->__data.__list.__next = NULL; \
260 } \
261 } while (0)
262#endif
263#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
264#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
265
266 /* List of cleanup buffers. */
267 struct _pthread_cleanup_buffer *cleanup;
268
269 /* Unwind information. */
270 struct pthread_unwind_buf *cleanup_jmp_buf;
271#define HAVE_CLEANUP_JMP_BUF
272
273 /* Flags determining processing of cancellation. */
274 int cancelhandling;
275 /* Bit set if cancellation is disabled. */
276#define CANCELSTATE_BIT 0
277#define CANCELSTATE_BITMASK (0x01 << CANCELSTATE_BIT)
278 /* Bit set if asynchronous cancellation mode is selected. */
279#define CANCELTYPE_BIT 1
280#define CANCELTYPE_BITMASK (0x01 << CANCELTYPE_BIT)
281 /* Bit set if canceling has been initiated. */
282#define CANCELING_BIT 2
283#define CANCELING_BITMASK (0x01 << CANCELING_BIT)
284 /* Bit set if canceled. */
285#define CANCELED_BIT 3
286#define CANCELED_BITMASK (0x01 << CANCELED_BIT)
287 /* Bit set if thread is exiting. */
288#define EXITING_BIT 4
289#define EXITING_BITMASK (0x01 << EXITING_BIT)
290 /* Bit set if thread terminated and TCB is freed. */
291#define TERMINATED_BIT 5
292#define TERMINATED_BITMASK (0x01 << TERMINATED_BIT)
293 /* Bit set if thread is supposed to change XID. */
294#define SETXID_BIT 6
295#define SETXID_BITMASK (0x01 << SETXID_BIT)
296 /* Mask for the rest. Helps the compiler to optimize. */
297#define CANCEL_RESTMASK 0xffffff80
298
299#define CANCEL_ENABLED_AND_CANCELED(value) \
300 (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK \
301 | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
302#define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
303 (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK \
304 | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK)) \
305 == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
306
307 /* Flags. Including those copied from the thread attribute. */
308 int flags;
309
310 /* We allocate one block of references here. This should be enough
311 to avoid allocating any memory dynamically for most applications. */
312 struct pthread_key_data
313 {
314 /* Sequence number. We use uintptr_t to not require padding on
315 32- and 64-bit machines. On 64-bit machines it helps to avoid
316 wrapping, too. */
317 uintptr_t seq;
318
319 /* Data pointer. */
320 void *data;
321 } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
322
323 /* Two-level array for the thread-specific data. */
324 struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
325
326 /* Flag which is set when specific data is set. */
327 bool specific_used;
328
329 /* True if events must be reported. */
330 bool report_events;
331
332 /* True if the user provided the stack. */
333 bool user_stack;
334
335 /* True if thread must stop at startup time. */
336 bool stopped_start;
337
338 /* The parent's cancel handling at the time of the pthread_create
339 call. This might be needed to undo the effects of a cancellation. */
340 int parent_cancelhandling;
341
342 /* Lock to synchronize access to the descriptor. */
343 int lock;
344
345 /* Lock for synchronizing setxid calls. */
346 unsigned int setxid_futex;
347
348#if HP_TIMING_AVAIL
349 /* Offset of the CPU clock at start thread start time. */
350 hp_timing_t cpuclock_offset;
351#endif
352
353 /* If the thread waits to join another one the ID of the latter is
354 stored here.
355
356 In case a thread is detached this field contains a pointer of the
357 TCB if the thread itself. This is something which cannot happen
358 in normal operation. */
359 struct pthread *joinid;
360 /* Check whether a thread is detached. */
361#define IS_DETACHED(pd) ((pd)->joinid == (pd))
362
363 /* The result of the thread function. */
364 void *result;
365
366 /* Scheduling parameters for the new thread. */
367 struct sched_param schedparam;
368 int schedpolicy;
369
370 /* Start position of the code to be executed and the argument passed
371 to the function. */
372 void *(*start_routine) (void *);
373 void *arg;
374
375 /* Debug state. */
376 td_eventbuf_t eventbuf;
377 /* Next descriptor with a pending event. */
378 struct pthread *nextevent;
379
380 /* Machine-specific unwind info. */
381 struct _Unwind_Exception exc;
382
383 /* If nonzero pointer to area allocated for the stack and its
384 size. */
385 void *stackblock;
386 size_t stackblock_size;
387 /* Size of the included guard area. */
388 size_t guardsize;
389 /* This is what the user specified and what we will report. */
390 size_t reported_guardsize;
391
392 /* Thread Priority Protection data. */
393 struct priority_protection_data *tpp;
394
395 /* Resolver state. */
396 struct __res_state res;
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