uclibc-ng/libpthread/nptl/sysdeps/riscv64/tls.h

/* Definition for thread-local data handling.  NPTL/RISCV64 version.
   Copyright (C) 2005, 2007, 2011 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _TLS_H
#define _TLS_H  1

#ifndef __ASSEMBLER__
# include <stdbool.h>
# include <stddef.h>
# include <stdint.h>

/* Type for the dtv.  */
typedef union dtv
{
  size_t counter;
  struct
  {
    void *val;
    bool is_static;
  } pointer;
} dtv_t;

typedef struct
{
  dtv_t *dtv;
} tcbhead_t;

register tcbhead_t *__thread_self __asm__("tp");

# define TLS_MULTIPLE_THREADS_IN_TCB 1

#else /* __ASSEMBLER__ */
# include <tcb-offsets.h>
#endif /* __ASSEMBLER__ */

/* We require TLS support in the tools.  */
#define HAVE_TLS_SUPPORT                1
#define HAVE_TLS_MODEL_ATTRIBUTE        1
#define HAVE___THREAD                   1

/* Signal that TLS support is available.  */
#define USE_TLS	1

#ifndef __ASSEMBLER__

/* Get system call information.  */
# include <sysdep.h>

/* The TP points to the start of the TLS block.
 * As I understand it, this isn't strictly that "TP points to DTV" - it's
 * more where to place the TCB in the TLS block. This will place it in 
 * the beginning.
 *
 * Layout:
 *  ------------------------------------
 *  | PRE | TCB | TLS MEMORY ..        |
 *  ------------------------------------
 *              ^ x4 / TP
 *
 * PRE is the struct pthread described below
 * TCB is tcbhead_t
 * TLS memory is where the TLS program sections are loaded
 *
 * See _dl_allocate_tls_storage and __libc_setup_tls for more information.
 */
# define TLS_DTV_AT_TP  1

/* Get the thread descriptor definition.  */
# include <../../descr.h>

/* Requirements for the TCB.  */
# define TLS_INIT_TCB_SIZE    sizeof (tcbhead_t)
# define TLS_INIT_TCB_ALIGN   __alignof__ (tcbhead_t)

# define TLS_TCB_SIZE         sizeof (tcbhead_t)
# define TLS_TCB_ALIGN        __alignof__ (tcbhead_t)

/* This is the size of the TCB.  */

/* This is the size we need before TCB.
 * To support THREAD_GETMEM with friends we want to have a
 * struct pthread available.
 * Yank it in infront of everything, I'm sure nobody will mind.
 *
 * This memory is really allocated PRE the TLS block, so it's possible
 * to do ((char*)tlsblock) - TLS_PRE_TCB_SIZE to access it.
 * This is done for THREAD_SELF. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)


/* Install the dtv pointer.
 * When called, dtvp is a pointer not the DTV per say (which should start
 * with the generation counter) but to the length of the DTV.
 * We can always index with -1, so we store dtvp[1]
 */
# define INSTALL_DTV(tcbp, dtvp) \
  (((tcbhead_t *) (tcbp))->dtv = (dtvp) + 1)

/* Install new dtv for current thread
 * In a logicial world dtv here would also point to the length of the DTV.
 * However it does not, this time it points to the generation counter,
 * so just store it.
 *
 * Note: -1 is still valid and contains the length. */
# define INSTALL_NEW_DTV(dtv) \
  (THREAD_DTV() = (dtv))

/* Return dtv of given thread descriptor.  */
# define GET_DTV(tcbp) \
  (((tcbhead_t *) (tcbp))->dtv)

/* Code to initially initialize the thread pointer.
 *
 * Set TP to the address _after_ tcbhead_t. This will allow us
 * to change the size of tcbhead_t without having to re-link everything.
 *
 * secondcall has something to do with USE__THREAD,
 * seems to always be 0 so we don't care about it.
 *
 * This has to return NULL on success (or a string with the failure text).
 * It's hard to fail this, so return NULL always.
 */
# define TLS_INIT_TP(tcbp, secondcall) \
  ({__thread_self = ((tcbhead_t *)tcbp + 1); NULL;})

/* Return the address of the dtv for the current thread.
 *
 * Dereference TP, offset to dtv - really straightforward.
 * Remember that we made TP point to after tcb, so we need to reverse that.
 */
#  define THREAD_DTV() \
  ((((tcbhead_t *)__thread_self)-1)->dtv)

/* Return the thread descriptor for the current thread. 
 *
 * Return a pointer to the TLS_PRE area where we allocated space for
 * a struct pthread. Again, TP points to after tcbhead_t, compensate with
 * TLS_INIT_TCB_SIZE.
 *
 * I regard this is a seperate system from the "normal" TLS.
 */
# define THREAD_SELF \
  ((struct pthread *) ((char *) __thread_self - TLS_INIT_TCB_SIZE \
    - TLS_PRE_TCB_SIZE))

/* Magic for libthread_db to know how to do THREAD_SELF.  */
# define DB_THREAD_SELF \
  CONST_THREAD_AREA (32, sizeof (struct pthread))

/* Access to data in the thread descriptor is easy.  */
#define THREAD_GETMEM(descr, member) \
  descr->member
#define THREAD_GETMEM_NC(descr, member, idx) \
  descr->member[idx]
#define THREAD_SETMEM(descr, member, value) \
  descr->member = (value)
#define THREAD_SETMEM_NC(descr, member, idx, value) \
  descr->member[idx] = (value)

/* Get and set the global scope generation counter in struct pthread.  */
#define THREAD_GSCOPE_FLAG_UNUSED 0
#define THREAD_GSCOPE_FLAG_USED   1
#define THREAD_GSCOPE_FLAG_WAIT   2
#define THREAD_GSCOPE_RESET_FLAG() \
  do                       \
    { int __res                    \
  = atomic_exchange_rel (&THREAD_SELF->header.gscope_flag,       \
             THREAD_GSCOPE_FLAG_UNUSED);         \
      if (__res == THREAD_GSCOPE_FLAG_WAIT)            \
  lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);   \
    }                      \
  while (0)
#define THREAD_GSCOPE_SET_FLAG() \
  do                       \
    {                      \
      THREAD_SELF->header.gscope_flag = THREAD_GSCOPE_FLAG_USED;       \
      atomic_write_barrier ();                 \
    }                      \
  while (0)
#define THREAD_GSCOPE_WAIT() \
  GL(dl_wait_lookup_done) ()

#endif /* __ASSEMBLER__ */

#endif  /* tls.h */