linuxthreads/sysdeps/mips/tls.h

   1 /* Definitions for thread-local data handling.  linuxthreads/MIPS version.
   2    Copyright (C) 2005 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 # define READ_THREAD_POINTER() \
  41     ({ void *__result;                                                        \
  42        asm volatile (".set\tpush\n\t.set\tmips32r2\n\t"                       \
  43                      "rdhwr\t%0, $29\n\t.set\tpop" : "=v" (__result));        \
  44        __result; })
  45
  46 #else /* __ASSEMBLER__ */
  47 # include <tcb-offsets.h>
  48
  49 /* Note: rd must be $v1 to be ABI-conformant.  */
  50 # define READ_THREAD_POINTER(rd) \
  51         .set    push;                                                         \
  52         .set    mips32r2;                                                     \
  53         rdhwr   rd, $29;                                                      \
  54         .set    pop
  55 #endif /* __ASSEMBLER__ */
  56
  57 /* LinuxThreads can only use TLS if both floating stacks (in the MIPS case,
  58    that means support for "rdhwr") and support from the tools are available.
  59
  60    We have to define USE_TLS consistently, or ldsodefs.h will lay out types
  61    differently between an NPTL build and a LinuxThreads build.  It can be set
  62    for libc.so and not libpthread.so, but only if we provide appropriate padding
  63    in the _pthread_descr_struct.
  64
  65    Currently nothing defines FLOATING_STACKS.  We could assume this based on
  66    kernel version once the TLS patches are available in kernel.org, but
  67    it hardly seems worth it.  Use NPTL if you can.
  68
  69    To avoid bothering with the TLS support code at all, use configure
  70    --without-tls.  */
  71
  72 #if defined HAVE_TLS_SUPPORT \
  73     && (defined FLOATING_STACKS || !defined IS_IN_libpthread)
  74
  75 /* Signal that TLS support is available.  */
  76 # define USE_TLS        1
  77
  78 /* Include padding in _pthread_descr_struct so that libc can find p_errno,
  79    if libpthread will only include the padding because of the !IS_IN_libpthread
  80    check.  */
  81 #ifndef FLOATING_STACKS
  82 # define INCLUDE_TLS_PADDING    1
  83 #endif
  84
  85 # ifndef __ASSEMBLER__
  86
  87 /* This layout is actually wholly private and not affected by the ABI.
  88    Nor does it overlap the pthread data structure, so we need nothing
  89    extra here at all.  */
  90 typedef struct
  91 {
  92   dtv_t *dtv;
  93   void *private;
  94 } tcbhead_t;
  95
  96 /* This is the size of the initial TCB.  */
  97 #  define TLS_INIT_TCB_SIZE     0
  98
  99 /* Alignment requirements for the initial TCB.  */
 100 #  define TLS_INIT_TCB_ALIGN    __alignof__ (struct _pthread_descr_struct)
 101
 102 /* This is the size of the TCB.  */
 103 #  define TLS_TCB_SIZE          0
 104
 105 /* Alignment requirements for the TCB.  */
 106 #  define TLS_TCB_ALIGN         __alignof__ (struct _pthread_descr_struct)
 107
 108 /* This is the size we need before TCB.  */
 109 #  define TLS_PRE_TCB_SIZE \
 110   (sizeof (struct _pthread_descr_struct)                                      \
 111    + ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
 112
 113 /* The thread pointer (in hardware register $29) points to the end of
 114    the TCB + 0x7000, as for PowerPC.  The pthread_descr structure is
 115    immediately in front of the TCB.  */
 116 #define TLS_TCB_OFFSET          0x7000
 117
 118 /* The DTV is allocated at the TP; the TCB is placed elsewhere.  */
 119 /* This is not really true for powerpc64.  We are following alpha
 120    where the DTV pointer is first doubleword in the TCB.  */
 121 #  define TLS_DTV_AT_TP 1
 122
 123 /* Install the dtv pointer.  The pointer passed is to the element with
 124    index -1 which contain the length.  */
 125 #  define INSTALL_DTV(TCBP, DTVP) \
 126   (((tcbhead_t *) (TCBP))[-1].dtv = (DTVP) + 1)
 127
 128 /* Install new dtv for current thread.  */
 129 #  define INSTALL_NEW_DTV(DTV) (THREAD_DTV() = (DTV))
 130
 131 /* Return dtv of given thread descriptor.  */
 132 #  define GET_DTV(TCBP) (((tcbhead_t *) (TCBP))[-1].dtv)
 133
 134 /* Code to initially initialize the thread pointer.  This might need
 135    special attention since 'errno' is not yet available and if the
 136    operation can cause a failure 'errno' must not be touched.  */
 137 # define TLS_INIT_TP(tcbp, secondcall) \
 138   ({ INTERNAL_SYSCALL_DECL (err);                                       \
 139      long result_var;                                                   \
 140      result_var = INTERNAL_SYSCALL (set_thread_area, err, 1,            \
 141                                     (char *) (tcbp) + TLS_TCB_OFFSET);  \
 142      INTERNAL_SYSCALL_ERROR_P (result_var, err)                         \
 143        ? "unknown error" : NULL; })
 144
 145 /* Return the address of the dtv for the current thread.  */
 146 # define THREAD_DTV() \
 147   (((tcbhead_t *) (READ_THREAD_POINTER () - TLS_TCB_OFFSET))[-1].dtv)
 148
 149 /* Return the thread descriptor for the current thread.  */
 150 #  undef THREAD_SELF
 151 #  define THREAD_SELF \
 152     ((pthread_descr) (READ_THREAD_POINTER () \
 153                       - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
 154
 155 /* Get the thread descriptor definition.  */
 156 #  include <linuxthreads/descr.h>
 157
 158 /* l_tls_offset == 0 is perfectly valid on MIPS, so we have to use some
 159    different value to mean unset l_tls_offset.  */
 160 #  define NO_TLS_OFFSET -1
 161
 162 /* Initializing the thread pointer requires a syscall which may not be
 163    available, so don't do it if we don't need to.  */
 164 #  define TLS_INIT_TP_EXPENSIVE 1
 165
 166 # endif /* __ASSEMBLER__ */
 167
 168 #endif /* HAVE_TLS_SUPPORT */
 169
 170 #endif  /* tls.h */