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   } 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.  */
  94 struct 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.  */
 104 struct 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.  */
 113 struct priority_protection_data
 114 {
 115   int priomax;
 116   unsigned int priomap[];
 117 };
 118
 119
 120 /* Thread descriptor data structure.  */
 121 struct 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 #if __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 the area allocated for the stack and guard. */
 384   void *stackblock;
 385   /* Size of the stackblock area including the guard.  */
 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 */