nptl/descr.h

   1 /* Copyright (C) 2002-2018 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.  */
  62 struct pthread_unwind_buf
  63 {
  64   struct
  65   {
  66     __jmp_buf jmp_buf;
  67     int mask_was_saved;
  68 #ifdef NEED_SAVED_MASK_IN_CANCEL_JMP_BUF
  69     __sigset_t saved_mask;
  70 #endif
  71   } cancel_jmp_buf[1];
  72
  73   union
  74   {
  75     /* This is the placeholder of the public version.  */
  76     void *pad[4];
  77
  78     struct
  79     {
  80       /* Pointer to the previous cleanup buffer.  */
  81       struct pthread_unwind_buf *prev;
  82
  83       /* Backward compatibility: state of the old-style cleanup
  84          handler at the time of the previous new-style cleanup handler
  85          installment.  */
  86       struct _pthread_cleanup_buffer *cleanup;
  87
  88       /* Cancellation type before the push call.  */
  89       int canceltype;
  90     } data;
  91   } priv;
  92 };
  93
  94
  95 /* Opcodes and data types for communication with the signal handler to
  96    change user/group IDs.  */
  97 struct xid_command
  98 {
  99   int syscall_no;
 100   long int id[3];
 101   volatile int cntr;
 102   volatile int error; /* -1: no call yet, 0: success seen, >0: error seen.  */
 103 };
 104
 105
 106 /* Data structure used by the kernel to find robust futexes.  */
 107 struct robust_list_head
 108 {
 109   void *list;
 110   long int futex_offset;
 111   void *list_op_pending;
 112 };
 113
 114
 115 /* Data strcture used to handle thread priority protection.  */
 116 struct priority_protection_data
 117 {
 118   int priomax;
 119   unsigned int priomap[];
 120 };
 121
 122
 123 /* Thread descriptor data structure.  */
 124 struct pthread
 125 {
 126   union
 127   {
 128 #if !TLS_DTV_AT_TP
 129     /* This overlaps the TCB as used for TLS without threads (see tls.h).  */
 130     tcbhead_t header;
 131 #else
 132     struct
 133     {
 134       /* multiple_threads is enabled either when the process has spawned at
 135          least one thread or when a single-threaded process cancels itself.
 136          This enables additional code to introduce locking before doing some
 137          compare_and_exchange operations and also enable cancellation points.
 138          The concepts of multiple threads and cancellation points ideally
 139          should be separate, since it is not necessary for multiple threads to
 140          have been created for cancellation points to be enabled, as is the
 141          case is when single-threaded process cancels itself.
 142
 143          Since enabling multiple_threads enables additional code in
 144          cancellation points and compare_and_exchange operations, there is a
 145          potential for an unneeded performance hit when it is enabled in a
 146          single-threaded, self-canceling process.  This is OK though, since a
 147          single-threaded process will enable async cancellation only when it
 148          looks to cancel itself and is hence going to end anyway.  */
 149       int multiple_threads;
 150       int gscope_flag;
 151 # ifndef __ASSUME_PRIVATE_FUTEX
 152       int private_futex;
 153 # endif
 154     } header;
 155 #endif
 156
 157     /* This extra padding has no special purpose, and this structure layout
 158        is private and subject to change without affecting the official ABI.
 159        We just have it here in case it might be convenient for some
 160        implementation-specific instrumentation hack or suchlike.  */
 161     void *__padding[24];
 162   };
 163
 164   /* This descriptor's link on the `stack_used' or `__stack_user' list.  */
 165   list_t list;
 166
 167   /* Thread ID - which is also a 'is this thread descriptor (and
 168      therefore stack) used' flag.  */
 169   pid_t tid;
 170
 171   /* Ununsed.  */
 172   pid_t pid_ununsed;
 173
 174   /* List of robust mutexes the thread is holding.  */
 175 #if __PTHREAD_MUTEX_HAVE_PREV
 176   void *robust_prev;
 177   struct robust_list_head robust_head;
 178
 179   /* The list above is strange.  It is basically a double linked list
 180      but the pointer to the next/previous element of the list points
 181      in the middle of the object, the __next element.  Whenever
 182      casting to __pthread_list_t we need to adjust the pointer
 183      first.
 184      These operations are effectively concurrent code in that the thread
 185      can get killed at any point in time and the kernel takes over.  Thus,
 186      the __next elements are a kind of concurrent list and we need to
 187      enforce using compiler barriers that the individual operations happen
 188      in such a way that the kernel always sees a consistent list.  The
 189      backward links (ie, the __prev elements) are not used by the kernel.
 190      FIXME We should use relaxed MO atomic operations here and signal fences
 191      because this kind of concurrency is similar to synchronizing with a
 192      signal handler.  */
 193 # define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
 194
 195 # define ENQUEUE_MUTEX_BOTH(mutex, val)                                       \
 196   do {                                                                        \
 197     __pthread_list_t *next = (__pthread_list_t *)                             \
 198       ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul)   \
 199        - QUEUE_PTR_ADJUST);                                                   \
 200     next->__prev = (void *) &mutex->__data.__list.__next;                     \
 201     mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF,                 \
 202                                                  robust_head.list);           \
 203     mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head;         \
 204     /* Ensure that the new list entry is ready before we insert it.  */       \
 205     __asm ("" ::: "memory");                                                  \
 206     THREAD_SETMEM (THREAD_SELF, robust_head.list,                             \
 207                    (void *) (((uintptr_t) &mutex->__data.__list.__next)       \
 208                              | val));                                         \
 209   } while (0)
 210 # define DEQUEUE_MUTEX(mutex) \
 211   do {                                                                        \
 212     __pthread_list_t *next = (__pthread_list_t *)                             \
 213       ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul)            \
 214        - QUEUE_PTR_ADJUST);                                                   \
 215     next->__prev = mutex->__data.__list.__prev;                               \
 216     __pthread_list_t *prev = (__pthread_list_t *)                             \
 217       ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul)            \
 218        - QUEUE_PTR_ADJUST);                                                   \
 219     prev->__next = mutex->__data.__list.__next;                               \
 220     /* Ensure that we remove the entry from the list before we change the     \
 221        __next pointer of the entry, which is read by the kernel.  */          \
 222     __asm ("" ::: "memory");                                                  \
 223     mutex->__data.__list.__prev = NULL;                                       \
 224     mutex->__data.__list.__next = NULL;                                       \
 225   } while (0)
 226 #else
 227   union
 228   {
 229     __pthread_slist_t robust_list;
 230     struct robust_list_head robust_head;
 231   };
 232
 233 # define ENQUEUE_MUTEX_BOTH(mutex, val)                                       \
 234   do {                                                                        \
 235     mutex->__data.__list.__next                                               \
 236       = THREAD_GETMEM (THREAD_SELF, robust_list.__next);                      \
 237     /* Ensure that the new list entry is ready before we insert it.  */       \
 238     __asm ("" ::: "memory");                                                  \
 239     THREAD_SETMEM (THREAD_SELF, robust_list.__next,                           \
 240                    (void *) (((uintptr_t) &mutex->__data.__list) | val));     \
 241   } while (0)
 242 # define DEQUEUE_MUTEX(mutex) \
 243   do {                                                                        \
 244     __pthread_slist_t *runp = (__pthread_slist_t *)                           \
 245       (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
 246     if (runp == &mutex->__data.__list)                                        \
 247       THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next);          \
 248     else                                                                      \
 249       {                                                                       \
 250         __pthread_slist_t *next = (__pthread_slist_t *)               \
 251           (((uintptr_t) runp->__next) & ~1ul);                                \
 252         while (next != &mutex->__data.__list)                                 \
 253           {                                                                   \
 254             runp = next;                                                      \
 255             next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
 256           }                                                                   \
 257                                                                               \
 258         runp->__next = next->__next;                                          \
 259         /* Ensure that we remove the entry from the list before we change the \
 260            __next pointer of the entry, which is read by the kernel.  */      \
 261             __asm ("" ::: "memory");                                          \
 262         mutex->__data.__list.__next = NULL;                                   \
 263       }                                                                       \
 264   } while (0)
 265 #endif
 266 #define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
 267 #define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
 268
 269   /* List of cleanup buffers.  */
 270   struct _pthread_cleanup_buffer *cleanup;
 271
 272   /* Unwind information.  */
 273   struct pthread_unwind_buf *cleanup_jmp_buf;
 274 #define HAVE_CLEANUP_JMP_BUF
 275
 276   /* Flags determining processing of cancellation.  */
 277   int cancelhandling;
 278   /* Bit set if cancellation is disabled.  */
 279 #define CANCELSTATE_BIT         0
 280 #define CANCELSTATE_BITMASK     (0x01 << CANCELSTATE_BIT)
 281   /* Bit set if asynchronous cancellation mode is selected.  */
 282 #define CANCELTYPE_BIT          1
 283 #define CANCELTYPE_BITMASK      (0x01 << CANCELTYPE_BIT)
 284   /* Bit set if canceling has been initiated.  */
 285 #define CANCELING_BIT           2
 286 #define CANCELING_BITMASK       (0x01 << CANCELING_BIT)
 287   /* Bit set if canceled.  */
 288 #define CANCELED_BIT            3
 289 #define CANCELED_BITMASK        (0x01 << CANCELED_BIT)
 290   /* Bit set if thread is exiting.  */
 291 #define EXITING_BIT             4
 292 #define EXITING_BITMASK         (0x01 << EXITING_BIT)
 293   /* Bit set if thread terminated and TCB is freed.  */
 294 #define TERMINATED_BIT          5
 295 #define TERMINATED_BITMASK      (0x01 << TERMINATED_BIT)
 296   /* Bit set if thread is supposed to change XID.  */
 297 #define SETXID_BIT              6
 298 #define SETXID_BITMASK          (0x01 << SETXID_BIT)
 299   /* Mask for the rest.  Helps the compiler to optimize.  */
 300 #define CANCEL_RESTMASK         0xffffff80
 301
 302 #define CANCEL_ENABLED_AND_CANCELED(value) \
 303   (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK       \
 304                | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
 305 #define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
 306   (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK    \
 307                | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK))     \
 308    == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
 309
 310   /* Flags.  Including those copied from the thread attribute.  */
 311   int flags;
 312
 313   /* We allocate one block of references here.  This should be enough
 314      to avoid allocating any memory dynamically for most applications.  */
 315   struct pthread_key_data
 316   {
 317     /* Sequence number.  We use uintptr_t to not require padding on
 318        32- and 64-bit machines.  On 64-bit machines it helps to avoid
 319        wrapping, too.  */
 320     uintptr_t seq;
 321
 322     /* Data pointer.  */
 323     void *data;
 324   } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
 325
 326   /* Two-level array for the thread-specific data.  */
 327   struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
 328
 329   /* Flag which is set when specific data is set.  */
 330   bool specific_used;
 331
 332   /* True if events must be reported.  */
 333   bool report_events;
 334
 335   /* True if the user provided the stack.  */
 336   bool user_stack;
 337
 338   /* True if thread must stop at startup time.  */
 339   bool stopped_start;
 340
 341   /* The parent's cancel handling at the time of the pthread_create
 342      call.  This might be needed to undo the effects of a cancellation.  */
 343   int parent_cancelhandling;
 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_AVAIL
 352   /* Offset of the CPU clock at start thread start time.  */
 353   hp_timing_t cpuclock_offset;
 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 area allocated for the stack and its
 387      size.  */
 388   void *stackblock;
 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   /* This member must be last.  */
 402   char end_padding[];
 403
 404 #define PTHREAD_STRUCT_END_PADDING \
 405   (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
 406 } __attribute ((aligned (TCB_ALIGNMENT)));
 407
 408
 409 #endif  /* descr.h */