1 /* Copyright (C) 2002-2006, 2007, 2008, 2009 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 <list.h>
28 #include <lowlevellock.h>
29 #include <pthreaddef.h>
30 #include "../nptl_db/thread_db.h"
31 #include <tls.h>
32 #ifdef HAVE_FORCED_UNWIND
33 # include <unwind.h>
34 #endif
35 #define __need_res_state
36 #include <resolv.h>
37 #include <bits/kernel-features.h>
38 #include "uClibc-glue.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.  */
64 struct 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.  */
96 struct xid_command
97 {
98   int syscall_no;
99   long int id[3];
100   volatile int cntr;
101 };
102 
103 
104 /* Data structure used by the kernel to find robust futexes.  */
105 struct robust_list_head
106 {
107   void *list;
108   long int futex_offset;
109   void *list_op_pending;
110 };
111 
112 
113 /* Data strcture used to handle thread priority protection.  */
114 struct priority_protection_data
115 {
116   int priomax;
117   unsigned int priomap[];
118 };
119 
120 
121 /* Thread descriptor data structure.  */
122 struct pthread
123 {
124   union
125   {
126 #if !defined(TLS_DTV_AT_TP)
127     /* This overlaps the TCB as used for TLS without threads (see tls.h).  */
128     tcbhead_t header;
129 #else
130     struct
131     {
132       int multiple_threads;
133       int gscope_flag;
134 # ifndef __ASSUME_PRIVATE_FUTEX
135       int private_futex;
136 # endif
137     } header;
138 #endif
139 
140     /* This extra padding has no special purpose, and this structure layout
141        is private and subject to change without affecting the official ABI.
142        We just have it here in case it might be convenient for some
143        implementation-specific instrumentation hack or suchlike.  */
144     void *__padding[24];
145   };
146 
147   /* This descriptor's link on the `stack_used' or `__stack_user' list.  */
148   list_t list;
149 
150   /* Thread ID - which is also a 'is this thread descriptor (and
151      therefore stack) used' flag.  */
152   pid_t tid;
153 
154   /* List of robust mutexes the thread is holding.  */
155 #ifdef __PTHREAD_MUTEX_HAVE_PREV
156   void *robust_prev;
157   struct robust_list_head robust_head;
158 
159   /* The list above is strange.  It is basically a double linked list
160      but the pointer to the next/previous element of the list points
161      in the middle of the object, the __next element.  Whenever
162      casting to __pthread_list_t we need to adjust the pointer
163      first.  */
164 # define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
165 
166 # define ENQUEUE_MUTEX_BOTH(mutex, val)					      \
167   do {									      \
168     __pthread_list_t *next = (__pthread_list_t *)			      \
169       ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul)   \
170        - QUEUE_PTR_ADJUST);						      \
171     next->__prev = (void *) &mutex->__data.__list.__next;		      \
172     mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF,		      \
173 						 robust_head.list);	      \
174     mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head;	      \
175     THREAD_SETMEM (THREAD_SELF, robust_head.list,			      \
176 		   (void *) (((uintptr_t) &mutex->__data.__list.__next)	      \
177 			     | val));					      \
178   } while (0)
179 # define DEQUEUE_MUTEX(mutex) \
180   do {									      \
181     __pthread_list_t *next = (__pthread_list_t *)			      \
182       ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul)	      \
183        - QUEUE_PTR_ADJUST);						      \
184     next->__prev = mutex->__data.__list.__prev;				      \
185     __pthread_list_t *prev = (__pthread_list_t *)			      \
186       ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul)	      \
187        - QUEUE_PTR_ADJUST);						      \
188     prev->__next = mutex->__data.__list.__next;				      \
189     mutex->__data.__list.__prev = NULL;					      \
190     mutex->__data.__list.__next = NULL;					      \
191   } while (0)
192 #else
193   union
194   {
195     __pthread_slist_t robust_list;
196     struct robust_list_head robust_head;
197   };
198 
199 # define ENQUEUE_MUTEX_BOTH(mutex, val)					      \
200   do {									      \
201     mutex->__data.__list.__next						      \
202       = THREAD_GETMEM (THREAD_SELF, robust_list.__next);		      \
203     THREAD_SETMEM (THREAD_SELF, robust_list.__next,			      \
204 		   (void *) (((uintptr_t) &mutex->__data.__list) | val));     \
205   } while (0)
206 # define DEQUEUE_MUTEX(mutex) \
207   do {									      \
208     __pthread_slist_t *runp = (__pthread_slist_t *)			      \
209       (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
210     if (runp == &mutex->__data.__list)					      \
211       THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next);	      \
212     else								      \
213       {									      \
214 	__pthread_slist_t *next = (__pthread_slist_t *)		      \
215 	  (((uintptr_t) runp->__next) & ~1ul);				      \
216 	while (next != &mutex->__data.__list)				      \
217 	  {								      \
218 	    runp = next;						      \
219 	    next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
220 	  }								      \
221 									      \
222 	runp->__next = next->__next;					      \
223 	mutex->__data.__list.__next = NULL;				      \
224       }									      \
225   } while (0)
226 #endif
227 #define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
228 #define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
229 
230   /* List of cleanup buffers.  */
231   struct _pthread_cleanup_buffer *cleanup;
232 
233   /* Unwind information.  */
234   struct pthread_unwind_buf *cleanup_jmp_buf;
235 #define HAVE_CLEANUP_JMP_BUF
236 
237   /* Flags determining processing of cancellation.  */
238   int cancelhandling;
239   /* Bit set if cancellation is disabled.  */
240 #define CANCELSTATE_BIT		0
241 #define CANCELSTATE_BITMASK	(0x01 << CANCELSTATE_BIT)
242   /* Bit set if asynchronous cancellation mode is selected.  */
243 #define CANCELTYPE_BIT		1
244 #define CANCELTYPE_BITMASK	(0x01 << CANCELTYPE_BIT)
245   /* Bit set if canceling has been initiated.  */
246 #define CANCELING_BIT		2
247 #define CANCELING_BITMASK	(0x01 << CANCELING_BIT)
248   /* Bit set if canceled.  */
249 #define CANCELED_BIT		3
250 #define CANCELED_BITMASK	(0x01 << CANCELED_BIT)
251   /* Bit set if thread is exiting.  */
252 #define EXITING_BIT		4
253 #define EXITING_BITMASK		(0x01 << EXITING_BIT)
254   /* Bit set if thread terminated and TCB is freed.  */
255 #define TERMINATED_BIT		5
256 #define TERMINATED_BITMASK	(0x01 << TERMINATED_BIT)
257   /* Bit set if thread is supposed to change XID.  */
258 #define SETXID_BIT		6
259 #define SETXID_BITMASK		(0x01 << SETXID_BIT)
260   /* Mask for the rest.  Helps the compiler to optimize.  */
261 #define CANCEL_RESTMASK		0xffffff80
262 
263 #define CANCEL_ENABLED_AND_CANCELED(value) \
264   (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK	      \
265 	       | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
266 #define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
267   (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK    \
268 	       | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK))     \
269    == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
270 
271   /* Flags.  Including those copied from the thread attribute.  */
272   int flags;
273 
274   /* We allocate one block of references here.  This should be enough
275      to avoid allocating any memory dynamically for most applications.  */
276   struct pthread_key_data
277   {
278     /* Sequence number.  We use uintptr_t to not require padding on
279        32- and 64-bit machines.  On 64-bit machines it helps to avoid
280        wrapping, too.  */
281     uintptr_t seq;
282 
283     /* Data pointer.  */
284     void *data;
285   } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
286 
287   /* Two-level array for the thread-specific data.  */
288   struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
289 
290   /* Flag which is set when specific data is set.  */
291   bool specific_used;
292 
293   /* True if events must be reported.  */
294   bool report_events;
295 
296   /* True if the user provided the stack.  */
297   bool user_stack;
298 
299   /* True if thread must stop at startup time.  */
300   bool stopped_start;
301 
302   /* The parent's cancel handling at the time of the pthread_create
303      call.  This might be needed to undo the effects of a cancellation.  */
304   int parent_cancelhandling;
305 
306   /* Lock to synchronize access to the descriptor.  */
307   int lock;
308 
309   /* Lock for synchronizing setxid calls.  */
310   int setxid_futex;
311 
312   /* If the thread waits to join another one the ID of the latter is
313      stored here.
314 
315      In case a thread is detached this field contains a pointer of the
316      TCB if the thread itself.  This is something which cannot happen
317      in normal operation.  */
318   struct pthread *joinid;
319   /* Check whether a thread is detached.  */
320 #define IS_DETACHED(pd) ((pd)->joinid == (pd))
321 
322   /* The result of the thread function.  */
323   void *result;
324 
325   /* Scheduling parameters for the new thread.  */
326   struct sched_param schedparam;
327   int schedpolicy;
328 
329   /* Start position of the code to be executed and the argument passed
330      to the function.  */
331   void *(*start_routine) (void *);
332   void *arg;
333 
334   /* Debug state.  */
335   td_eventbuf_t eventbuf;
336   /* Next descriptor with a pending event.  */
337   struct pthread *nextevent;
338 
339 #ifdef HAVE_FORCED_UNWIND
340   /* Machine-specific unwind info.  */
341   struct _Unwind_Exception exc;
342 #endif
343 
344   /* If nonzero pointer to area allocated for the stack and its
345      size.  */
346   void *stackblock;
347   size_t stackblock_size;
348   /* Size of the included guard area.  */
349   size_t guardsize;
350   /* This is what the user specified and what we will report.  */
351   size_t reported_guardsize;
352 
353   /* Thread Priority Protection data.  */
354   struct priority_protection_data *tpp;
355 
356   /* Resolver state.  */
357   struct __res_state res;
358 
359   /* This member must be last.  */
360   char end_padding[];
361 
362 #define PTHREAD_STRUCT_END_PADDING \
363   (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
364 } __attribute ((aligned (TCB_ALIGNMENT)));
365 
366 
367 #endif	/* descr.h */
368