nptl/descr.h

   1 /* Copyright (C) 2002-2020 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    <https://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 <thread_db.h>
  33 #include <tls.h>
  34 #include <unwind.h>
  35 #include <bits/types/res_state.h>
  36 #include <kernel-features.h>
  37 #include <tls-internal-struct.h>
  38
  39 #ifndef TCB_ALIGNMENT
  40 # define TCB_ALIGNMENT  sizeof (double)
  41 #endif
  42
  43
  44 /* We keep thread specific data in a special data structure, a two-level
  45    array.  The top-level array contains pointers to dynamically allocated
  46    arrays of a certain number of data pointers.  So we can implement a
  47    sparse array.  Each dynamic second-level array has
  48         PTHREAD_KEY_2NDLEVEL_SIZE
  49    entries.  This value shouldn't be too large.  */
  50 #define PTHREAD_KEY_2NDLEVEL_SIZE       32
  51
  52 /* We need to address PTHREAD_KEYS_MAX key with PTHREAD_KEY_2NDLEVEL_SIZE
  53    keys in each subarray.  */
  54 #define PTHREAD_KEY_1STLEVEL_SIZE \
  55   ((PTHREAD_KEYS_MAX + PTHREAD_KEY_2NDLEVEL_SIZE - 1) \
  56    / PTHREAD_KEY_2NDLEVEL_SIZE)
  57
  58
  59
  60
  61 /* Internal version of the buffer to store cancellation handler
  62    information.  */
  63 struct pthread_unwind_buf
  64 {
  65   struct
  66   {
  67     __jmp_buf jmp_buf;
  68     int mask_was_saved;
  69   } cancel_jmp_buf[1];
  70
  71   union
  72   {
  73     /* This is the placeholder of the public version.  */
  74     void *pad[4];
  75
  76     struct
  77     {
  78       /* Pointer to the previous cleanup buffer.  */
  79       struct pthread_unwind_buf *prev;
  80
  81       /* Backward compatibility: state of the old-style cleanup
  82          handler at the time of the previous new-style cleanup handler
  83          installment.  */
  84       struct _pthread_cleanup_buffer *cleanup;
  85
  86       /* Cancellation type before the push call.  */
  87       int canceltype;
  88     } data;
  89   } priv;
  90 };
  91
  92
  93 /* Opcodes and data types for communication with the signal handler to
  94    change user/group IDs.  */
  95 struct xid_command
  96 {
  97   int syscall_no;
  98   /* Enforce zero-extension for the pointer argument in
  99
 100      int setgroups (size_t size, const gid_t *list);
 101
 102      The kernel XID arguments are unsigned and do not require sign
 103      extension.  */
 104   unsigned long int id[3];
 105   volatile int cntr;
 106   volatile int error; /* -1: no call yet, 0: success seen, >0: error seen.  */
 107 };
 108
 109
 110 /* Data structure used by the kernel to find robust futexes.  */
 111 struct robust_list_head
 112 {
 113   void *list;
 114   long int futex_offset;
 115   void *list_op_pending;
 116 };
 117
 118
 119 /* Data strcture used to handle thread priority protection.  */
 120 struct priority_protection_data
 121 {
 122   int priomax;
 123   unsigned int priomap[];
 124 };
 125
 126
 127 /* Thread descriptor data structure.  */
 128 struct pthread
 129 {
 130   union
 131   {
 132 #if !TLS_DTV_AT_TP
 133     /* This overlaps the TCB as used for TLS without threads (see tls.h).  */
 134     tcbhead_t header;
 135 #else
 136     struct
 137     {
 138       /* multiple_threads is enabled either when the process has spawned at
 139          least one thread or when a single-threaded process cancels itself.
 140          This enables additional code to introduce locking before doing some
 141          compare_and_exchange operations and also enable cancellation points.
 142          The concepts of multiple threads and cancellation points ideally
 143          should be separate, since it is not necessary for multiple threads to
 144          have been created for cancellation points to be enabled, as is the
 145          case is when single-threaded process cancels itself.
 146
 147          Since enabling multiple_threads enables additional code in
 148          cancellation points and compare_and_exchange operations, there is a
 149          potential for an unneeded performance hit when it is enabled in a
 150          single-threaded, self-canceling process.  This is OK though, since a
 151          single-threaded process will enable async cancellation only when it
 152          looks to cancel itself and is hence going to end anyway.  */
 153       int multiple_threads;
 154       int gscope_flag;
 155     } header;
 156 #endif
 157
 158     /* This extra padding has no special purpose, and this structure layout
 159        is private and subject to change without affecting the official ABI.
 160        We just have it here in case it might be convenient for some
 161        implementation-specific instrumentation hack or suchlike.  */
 162     void *__padding[24];
 163   };
 164
 165   /* This descriptor's link on the GL (dl_stack_used) or
 166      GL (dl_stack_user) list.  */
 167   list_t list;
 168
 169   /* Thread ID - which is also a 'is this thread descriptor (and
 170      therefore stack) used' flag.  */
 171   pid_t tid;
 172
 173   /* Ununsed.  */
 174   pid_t pid_ununsed;
 175
 176   /* List of robust mutexes the thread is holding.  */
 177 #if __PTHREAD_MUTEX_HAVE_PREV
 178   void *robust_prev;
 179   struct robust_list_head robust_head;
 180
 181   /* The list above is strange.  It is basically a double linked list
 182      but the pointer to the next/previous element of the list points
 183      in the middle of the object, the __next element.  Whenever
 184      casting to __pthread_list_t we need to adjust the pointer
 185      first.
 186      These operations are effectively concurrent code in that the thread
 187      can get killed at any point in time and the kernel takes over.  Thus,
 188      the __next elements are a kind of concurrent list and we need to
 189      enforce using compiler barriers that the individual operations happen
 190      in such a way that the kernel always sees a consistent list.  The
 191      backward links (ie, the __prev elements) are not used by the kernel.
 192      FIXME We should use relaxed MO atomic operations here and signal fences
 193      because this kind of concurrency is similar to synchronizing with a
 194      signal handler.  */
 195 # define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
 196
 197 # define ENQUEUE_MUTEX_BOTH(mutex, val)                                       \
 198   do {                                                                        \
 199     __pthread_list_t *next = (__pthread_list_t *)                             \
 200       ((((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_head.list)) & ~1ul)   \
 201        - QUEUE_PTR_ADJUST);                                                   \
 202     next->__prev = (void *) &mutex->__data.__list.__next;                     \
 203     mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF,                 \
 204                                                  robust_head.list);           \
 205     mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head;         \
 206     /* Ensure that the new list entry is ready before we insert it.  */       \
 207     __asm ("" ::: "memory");                                                  \
 208     THREAD_SETMEM (THREAD_SELF, robust_head.list,                             \
 209                    (void *) (((uintptr_t) &mutex->__data.__list.__next)       \
 210                              | val));                                         \
 211   } while (0)
 212 # define DEQUEUE_MUTEX(mutex) \
 213   do {                                                                        \
 214     __pthread_list_t *next = (__pthread_list_t *)                             \
 215       ((char *) (((uintptr_t) mutex->__data.__list.__next) & ~1ul)            \
 216        - QUEUE_PTR_ADJUST);                                                   \
 217     next->__prev = mutex->__data.__list.__prev;                               \
 218     __pthread_list_t *prev = (__pthread_list_t *)                             \
 219       ((char *) (((uintptr_t) mutex->__data.__list.__prev) & ~1ul)            \
 220        - QUEUE_PTR_ADJUST);                                                   \
 221     prev->__next = mutex->__data.__list.__next;                               \
 222     /* Ensure that we remove the entry from the list before we change the     \
 223        __next pointer of the entry, which is read by the kernel.  */          \
 224     __asm ("" ::: "memory");                                                  \
 225     mutex->__data.__list.__prev = NULL;                                       \
 226     mutex->__data.__list.__next = NULL;                                       \
 227   } while (0)
 228 #else
 229   union
 230   {
 231     __pthread_slist_t robust_list;
 232     struct robust_list_head robust_head;
 233   };
 234
 235 # define ENQUEUE_MUTEX_BOTH(mutex, val)                                       \
 236   do {                                                                        \
 237     mutex->__data.__list.__next                                               \
 238       = THREAD_GETMEM (THREAD_SELF, robust_list.__next);                      \
 239     /* Ensure that the new list entry is ready before we insert it.  */       \
 240     __asm ("" ::: "memory");                                                  \
 241     THREAD_SETMEM (THREAD_SELF, robust_list.__next,                           \
 242                    (void *) (((uintptr_t) &mutex->__data.__list) | val));     \
 243   } while (0)
 244 # define DEQUEUE_MUTEX(mutex) \
 245   do {                                                                        \
 246     __pthread_slist_t *runp = (__pthread_slist_t *)                           \
 247       (((uintptr_t) THREAD_GETMEM (THREAD_SELF, robust_list.__next)) & ~1ul); \
 248     if (runp == &mutex->__data.__list)                                        \
 249       THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next);          \
 250     else                                                                      \
 251       {                                                                       \
 252         __pthread_slist_t *next = (__pthread_slist_t *)               \
 253           (((uintptr_t) runp->__next) & ~1ul);                                \
 254         while (next != &mutex->__data.__list)                                 \
 255           {                                                                   \
 256             runp = next;                                                      \
 257             next = (__pthread_slist_t *) (((uintptr_t) runp->__next) & ~1ul); \
 258           }                                                                   \
 259                                                                               \
 260         runp->__next = next->__next;                                          \
 261         /* Ensure that we remove the entry from the list before we change the \
 262            __next pointer of the entry, which is read by the kernel.  */      \
 263             __asm ("" ::: "memory");                                          \
 264         mutex->__data.__list.__next = NULL;                                   \
 265       }                                                                       \
 266   } while (0)
 267 #endif
 268 #define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
 269 #define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
 270
 271   /* List of cleanup buffers.  */
 272   struct _pthread_cleanup_buffer *cleanup;
 273
 274   /* Unwind information.  */
 275   struct pthread_unwind_buf *cleanup_jmp_buf;
 276 #define HAVE_CLEANUP_JMP_BUF
 277
 278   /* Flags determining processing of cancellation.  */
 279   int cancelhandling;
 280   /* Bit set if cancellation is disabled.  */
 281 #define CANCELSTATE_BIT         0
 282 #define CANCELSTATE_BITMASK     (0x01 << CANCELSTATE_BIT)
 283   /* Bit set if asynchronous cancellation mode is selected.  */
 284 #define CANCELTYPE_BIT          1
 285 #define CANCELTYPE_BITMASK      (0x01 << CANCELTYPE_BIT)
 286   /* Bit set if canceling has been initiated.  */
 287 #define CANCELING_BIT           2
 288 #define CANCELING_BITMASK       (0x01 << CANCELING_BIT)
 289   /* Bit set if canceled.  */
 290 #define CANCELED_BIT            3
 291 #define CANCELED_BITMASK        (0x01 << CANCELED_BIT)
 292   /* Bit set if thread is exiting.  */
 293 #define EXITING_BIT             4
 294 #define EXITING_BITMASK         (0x01 << EXITING_BIT)
 295   /* Bit set if thread terminated and TCB is freed.  */
 296 #define TERMINATED_BIT          5
 297 #define TERMINATED_BITMASK      (0x01 << TERMINATED_BIT)
 298   /* Bit set if thread is supposed to change XID.  */
 299 #define SETXID_BIT              6
 300 #define SETXID_BITMASK          (0x01 << SETXID_BIT)
 301   /* Mask for the rest.  Helps the compiler to optimize.  */
 302 #define CANCEL_RESTMASK         0xffffff80
 303
 304 #define CANCEL_ENABLED_AND_CANCELED(value) \
 305   (((value) & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK       \
 306                | CANCEL_RESTMASK | TERMINATED_BITMASK)) == CANCELED_BITMASK)
 307 #define CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS(value) \
 308   (((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK    \
 309                | EXITING_BITMASK | CANCEL_RESTMASK | TERMINATED_BITMASK))     \
 310    == (CANCELTYPE_BITMASK | CANCELED_BITMASK))
 311
 312   /* Flags.  Including those copied from the thread attribute.  */
 313   int flags;
 314
 315   /* We allocate one block of references here.  This should be enough
 316      to avoid allocating any memory dynamically for most applications.  */
 317   struct pthread_key_data
 318   {
 319     /* Sequence number.  We use uintptr_t to not require padding on
 320        32- and 64-bit machines.  On 64-bit machines it helps to avoid
 321        wrapping, too.  */
 322     uintptr_t seq;
 323
 324     /* Data pointer.  */
 325     void *data;
 326   } specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
 327
 328   /* Two-level array for the thread-specific data.  */
 329   struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
 330
 331   /* Flag which is set when specific data is set.  */
 332   bool specific_used;
 333
 334   /* True if events must be reported.  */
 335   bool report_events;
 336
 337   /* True if the user provided the stack.  */
 338   bool user_stack;
 339
 340   /* True if thread must stop at startup time.  */
 341   bool stopped_start;
 342
 343   /* Formerly used for dealing with cancellation.  */
 344   int parent_cancelhandling_unsed;
 345
 346   /* Lock to synchronize access to the descriptor.  */
 347   int lock;
 348
 349   /* Lock for synchronizing setxid calls.  */
 350   unsigned int setxid_futex;
 351
 352 #if HP_TIMING_INLINE
 353   hp_timing_t cpuclock_offset_ununsed;
 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 the area allocated for the stack and guard. */
 387   void *stackblock;
 388   /* Size of the stackblock area including the guard.  */
 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   /* Signal mask for the new thread.  Used during thread startup to
 402      restore the signal mask.  (Threads are launched with all signals
 403      masked.)  */
 404   sigset_t sigmask;
 405
 406   /* Indicates whether is a C11 thread created by thrd_creat.  */
 407   bool c11;
 408
 409   /* Used on strsignal.  */
 410   struct tls_internal_t tls_state;
 411
 412   /* This member must be last.  */
 413   char end_padding[];
 414
 415 #define PTHREAD_STRUCT_END_PADDING \
 416   (sizeof (struct pthread) - offsetof (struct pthread, end_padding))
 417 } __attribute ((aligned (TCB_ALIGNMENT)));
 418
 419
 420 #endif  /* descr.h */