sysdeps/riscv/nptl/tls.h

   1 /* Definition for thread-local data handling.  NPTL/RISC-V version.
   2    Copyright (C) 2011-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 _RISCV_TLS_H
  20 #define _RISCV_TLS_H    1
  21
  22 #include <dl-sysdep.h>
  23
  24 #ifndef __ASSEMBLER__
  25 # include <stdbool.h>
  26 # include <stddef.h>
  27 # include <stdint.h>
  28 # include <dl-dtv.h>
  29
  30 register void *__thread_self asm ("tp");
  31 # define READ_THREAD_POINTER() ({ __thread_self; })
  32
  33 /* Get system call information.  */
  34 # include <sysdep.h>
  35
  36 /* The TP points to the start of the thread blocks.  */
  37 # define TLS_DTV_AT_TP  1
  38 # define TLS_TCB_AT_TP  0
  39
  40 /* Get the thread descriptor definition.  */
  41 # include <nptl/descr.h>
  42
  43 typedef struct
  44 {
  45   dtv_t *dtv;
  46   void *private;
  47 } tcbhead_t;
  48
  49 /* This is the size of the initial TCB.  Because our TCB is before the thread
  50    pointer, we don't need this.  */
  51 # define TLS_INIT_TCB_SIZE      0
  52
  53 /* This is the size of the TCB.  Because our TCB is before the thread
  54    pointer, we don't need this.  */
  55 # define TLS_TCB_SIZE           0
  56
  57 /* This is the size we need before TCB - actually, it includes the TCB.  */
  58 # define TLS_PRE_TCB_SIZE \
  59   (sizeof (struct pthread)                                                    \
  60    + ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1)                   \
  61       & ~(__alignof (struct pthread) - 1)))
  62
  63 /* The thread pointer tp points to the end of the TCB.
  64    The pthread_descr structure is immediately in front of the TCB.  */
  65 # define TLS_TCB_OFFSET 0
  66
  67 /* Install the dtv pointer.  The pointer passed is to the element with
  68    index -1 which contain the length.  */
  69 # define INSTALL_DTV(tcbp, dtvp) \
  70   (((tcbhead_t *) (tcbp))[-1].dtv = (dtvp) + 1)
  71
  72 /* Install new dtv for current thread.  */
  73 # define INSTALL_NEW_DTV(dtv) \
  74   (THREAD_DTV() = (dtv))
  75
  76 /* Return dtv of given thread descriptor.  */
  77 # define GET_DTV(tcbp) \
  78   (((tcbhead_t *) (tcbp))[-1].dtv)
  79
  80 /* Code to initially initialize the thread pointer.  */
  81 # define TLS_INIT_TP(tcbp) \
  82   ({ __thread_self = (char*)tcbp + TLS_TCB_OFFSET; true; })
  83
  84 /* Return the address of the dtv for the current thread.  */
  85 # define THREAD_DTV() \
  86   (((tcbhead_t *) (READ_THREAD_POINTER () - TLS_TCB_OFFSET))[-1].dtv)
  87
  88 /* Return the thread descriptor for the current thread.  */
  89 # define THREAD_SELF \
  90  ((struct pthread *) (READ_THREAD_POINTER ()                         \
  91                       - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
  92
  93 /* Value passed to 'clone' for initialization of the thread register.  */
  94 # define TLS_DEFINE_INIT_TP(tp, pd) \
  95   void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE
  96
  97 /* Informs libthread_db that the thread pointer is register 4, which is used
  98  * to know how to do THREAD_SELF.  */
  99 # define DB_THREAD_SELF \
 100   REGISTER (64, 64, 4 * 8, - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
 101
 102 /* Access to data in the thread descriptor is easy.  */
 103 # include <tcb-access.h>
 104
 105 /* l_tls_offset == 0 is perfectly valid, so we have to use some different
 106    value to mean unset l_tls_offset.  */
 107 # define NO_TLS_OFFSET          -1
 108
 109 /* Get and set the global scope generation counter in struct pthread.  */
 110 # define THREAD_GSCOPE_FLAG_UNUSED 0
 111 # define THREAD_GSCOPE_FLAG_USED   1
 112 # define THREAD_GSCOPE_FLAG_WAIT   2
 113 # define THREAD_GSCOPE_RESET_FLAG() \
 114   do                                                                         \
 115     { int __res                                                              \
 116         = atomic_exchange_release (&THREAD_SELF->header.gscope_flag,         \
 117                                THREAD_GSCOPE_FLAG_UNUSED);                   \
 118       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                  \
 119         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);   \
 120     }                                                                        \
 121   while (0)
 122 # define THREAD_GSCOPE_SET_FLAG() \
 123   do                                                                         \
 124     {                                                                        \
 125       THREAD_SELF->header.gscope_flag = THREAD_GSCOPE_FLAG_USED;             \
 126       atomic_write_barrier ();                                               \
 127     }                                                                        \
 128   while (0)
 129
 130 #endif /* __ASSEMBLER__ */
 131
 132 #endif  /* tls.h */