sysdeps/arm/linuxthreads/tls.h

   1 /* Definitions for thread-local data handling.  linuxthreads/ARM version.
   2    Copyright (C) 2004 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #ifndef _TLS_H
  21 #define _TLS_H
  22
  23 #ifndef __ASSEMBLER__
  24
  25 # include <stdbool.h>
  26 # include <pt-machine.h>
  27 # include <stddef.h>
  28
  29 /* Type for the dtv.  */
  30 typedef union dtv
  31 {
  32   size_t counter;
  33   struct
  34   {
  35     void *val;
  36     bool is_static;
  37   } pointer;
  38 } dtv_t;
  39
  40 typedef struct
  41 {
  42   dtv_t *dtv;
  43
  44   /* Reserved for the thread implementation.  Unused in LinuxThreads.  */
  45   void *private;
  46 } tcbhead_t;
  47 #endif
  48
  49
  50 /* We can support TLS only if the floating-stack support is available.
  51    However, we want to compile in the support and test at runtime whether
  52    the running kernel can support it or not.  To avoid bothering with the
  53    TLS support code at all, use configure --without-tls.
  54
  55    We need USE_TLS to be consistently defined, for ldsodefs.h conditionals.
  56    But some of the code below can cause problems in building libpthread
  57    (e.g. useldt.h will defined FLOATING_STACKS when it shouldn't).  */
  58
  59 /* LinuxThreads can only support TLS if both floating stacks and support
  60    from the tools are available.
  61
  62    We have to define USE_TLS consistently, or ldsodefs.h will lay out types
  63    differently between an NPTL build and a LinuxThreads build.  It can be set
  64    for libc.so and not libpthread.so, but only if we provide appropriate padding
  65    in the _pthread_descr_struct.
  66
  67    Currently nothing defines FLOATING_STACKS.  We could assume this based on
  68    kernel version once the TLS patches are available in kernel.org.
  69
  70    To avoid bothering with the TLS support code at all, use configure
  71    --without-tls.  */
  72
  73 #if defined HAVE_TLS_SUPPORT \
  74     && (defined FLOATING_STACKS || !defined IS_IN_libpthread)
  75
  76 /* Signal that TLS support is available.  */
  77 # define USE_TLS        1
  78
  79 /* Include padding in _pthread_descr_struct so that libc can find p_errno,
  80    if libpthread will only include the padding because of the !IS_IN_libpthread
  81    check.  */
  82 #ifndef FLOATING_STACKS
  83 # define INCLUDE_TLS_PADDING    1
  84 #endif
  85
  86 # ifndef __ASSEMBLER__
  87 /* Get system call information.  */
  88 #  include <sysdep.h>
  89
  90 /* This is the size of the initial TCB.  */
  91 #  define TLS_INIT_TCB_SIZE     sizeof (tcbhead_t)
  92
  93 /* Alignment requirements for the initial TCB.  */
  94 #  define TLS_INIT_TCB_ALIGN    __alignof__ (tcbhead_t)
  95
  96 /* This is the size of the TCB.  */
  97 #  define TLS_TCB_SIZE          sizeof (tcbhead_t)
  98
  99 /* Alignment requirements for the TCB.  */
 100 #  define TLS_TCB_ALIGN         __alignof__ (tcbhead_t)
 101
 102 /* This is the size we need before TCB.  */
 103 #  define TLS_PRE_TCB_SIZE      sizeof (struct _pthread_descr_struct)
 104
 105 /* The DTV is allocated at the TP; the TCB is placed elsewhere.  */
 106 #  define TLS_DTV_AT_TP 1
 107
 108 /* Install the dtv pointer.  The pointer passed is to the element with
 109    index -1 which contain the length.  */
 110 #  define INSTALL_DTV(TCBP, DTVP) \
 111   (((tcbhead_t *) (TCBP))->dtv = (DTVP) + 1)
 112
 113 /* Install new dtv for current thread.  */
 114 #  define INSTALL_NEW_DTV(DTV) \
 115   (((tcbhead_t *)__builtin_thread_pointer ())->dtv = (DTV))
 116
 117 /* Return dtv of given thread descriptor.  */
 118 #  define GET_DTV(TCBP) \
 119   (((tcbhead_t *) (TCBP))->dtv)
 120
 121 /* Code to initially initialize the thread pointer.  This might need
 122    special attention since 'errno' is not yet available and if the
 123    operation can cause a failure 'errno' must not be touched.  */
 124 # define TLS_INIT_TP(TCBP, SECONDCALL) \
 125   ({ INTERNAL_SYSCALL_DECL (err);                                       \
 126      long result_var;                                                   \
 127      result_var = INTERNAL_SYSCALL_ARM (set_tls, err, 1, (TCBP));       \
 128      INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
 129        ? "unknown error" : NULL; })
 130
 131 /* Return the address of the dtv for the current thread.  */
 132 #  define THREAD_DTV() \
 133   (((tcbhead_t *)__builtin_thread_pointer ())->dtv)
 134
 135 /* Return the thread descriptor for the current thread.  */
 136 #  undef THREAD_SELF
 137 #  define THREAD_SELF \
 138   ((pthread_descr)__builtin_thread_pointer () - 1)
 139
 140 #  undef INIT_THREAD_SELF
 141 #  define INIT_THREAD_SELF(DESCR, NR) \
 142   TLS_INIT_TP ((struct _pthread_descr_struct *)(DESCR) + 1, 0)
 143
 144 /* Get the thread descriptor definition.  */
 145 #  include <linuxthreads/descr.h>
 146
 147 /* ??? Generic bits of LinuxThreads may call these macros with
 148    DESCR set to NULL.  We are expected to be able to reference
 149    the "current" value.
 150
 151    In our case, we'd really prefer to use DESCR, since lots of
 152    PAL_code calls would be expensive.  We can only trust that
 153    the compiler does its job and unifies the multiple
 154    __builtin_thread_pointer instances.  */
 155
 156 #define THREAD_GETMEM(descr, member) \
 157   ((void) sizeof (descr), THREAD_SELF->member)
 158 #define THREAD_GETMEM_NC(descr, member) \
 159   ((void) sizeof (descr), THREAD_SELF->member)
 160 #define THREAD_SETMEM(descr, member, value) \
 161   ((void) sizeof (descr), THREAD_SELF->member = (value))
 162 #define THREAD_SETMEM_NC(descr, member, value) \
 163   ((void) sizeof (descr), THREAD_SELF->member = (value))
 164
 165 /* Initializing the thread pointer will generate a SIGILL if the syscall
 166    is not available.  */
 167 #define TLS_INIT_TP_EXPENSIVE 1
 168
 169 # endif /* HAVE_TLS_SUPPORT */
 170 #endif /* __ASSEMBLER__ */
 171
 172 #endif  /* tls.h */