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tls.h

/* Definition for thread-local data handling.  nptl/i386 version.
   Copyright (C) 2002, 2003 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _TLS_H
#define _TLS_H    1

#include <dl-sysdep.h>
#ifndef __ASSEMBLER__
# include <stddef.h>
# include <stdint.h>
# include <stdlib.h>
# include <list.h>


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


typedef struct
{
  void *tcb;            /* Pointer to the TCB.  Not necessary the
                     thread descriptor used by libpthread.  */
  dtv_t *dtv;
  void *self;           /* Pointer to the thread descriptor.  */
  int multiple_threads;
  uintptr_t sysinfo;
} tcbhead_t;

# define TLS_MULTIPLE_THREADS_IN_TCB 1

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


/* We require TLS support in the tools.  */
#ifndef HAVE_TLS_SUPPORT
# error "TLS support is required."
#endif

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

/* Alignment requirement for the stack.  For IA-32 this is governed by
   the SSE memory functions.  */
#define STACK_ALIGN     16

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

/* The old way: using LDT.  */

/* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
struct user_desc
{
  unsigned int entry_number;
  unsigned long int base_addr;
  unsigned int limit;
  unsigned int seg_32bit:1;
  unsigned int contents:2;
  unsigned int read_exec_only:1;
  unsigned int limit_in_pages:1;
  unsigned int seg_not_present:1;
  unsigned int useable:1;
  unsigned int empty:25;
};

/* Initializing bit fields is slow.  We speed it up by using a union.  */
union user_desc_init
{
  struct user_desc desc;
  unsigned int vals[4];
};


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

/* This is the size of the initial TCB.  */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)

/* Alignment requirements for the initial TCB.  */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)

/* This is the size of the TCB.  */
# define TLS_TCB_SIZE sizeof (struct pthread)

/* Alignment requirements for the TCB.  */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)

/* The TCB can have any size and the memory following the address the
   thread pointer points to is unspecified.  Allocate the TCB there.  */
# define TLS_TCB_AT_TP  1


/* Install the dtv pointer.  The pointer passed is to the element with
   index -1 which contain the length.  */
# define INSTALL_DTV(descr, dtvp) \
  ((tcbhead_t *) (descr))->dtv = (dtvp) + 1

/* Install new dtv for current thread.  */
# define INSTALL_NEW_DTV(dtvp) \
  ({ struct pthread *__pd;                                        \
     THREAD_SETMEM (__pd, header.dtv, (dtvp)); })

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


/* Macros to load from and store into segment registers.  */
# ifndef TLS_GET_GS
#  define TLS_GET_GS() \
  ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
# endif
# ifndef TLS_SET_GS
#  define TLS_SET_GS(val) \
  __asm ("movw %w0, %%gs" :: "q" (val))
# endif


# ifndef __NR_set_thread_area
#  define __NR_set_thread_area 243
# endif
# ifndef TLS_FLAG_WRITABLE
#  define TLS_FLAG_WRITABLE         0x00000001
# endif

// XXX Enable for the real world.
#if 0
# ifndef __ASSUME_SET_THREAD_AREA
#  error "we need set_thread_area"
# endif
#endif

# ifdef __PIC__
#  define TLS_EBX_ARG "r"
#  define TLS_LOAD_EBX "xchgl %3, %%ebx\n\t"
# else
#  define TLS_EBX_ARG "b"
#  define TLS_LOAD_EBX
# endif

#if defined NEED_DL_SYSINFO
# define INIT_SYSINFO \
  _head->sysinfo = GL(dl_sysinfo)
#else
# define INIT_SYSINFO
#endif

#ifndef LOCK_PREFIX
# ifdef UP
#  define LOCK_PREFIX  /* nothing */
# else
#  define LOCK_PREFIX "lock;"
# endif
#endif

/* Code to initially initialize the thread pointer.  This might need
   special attention since 'errno' is not yet available and if the
   operation can cause a failure 'errno' must not be touched.  */
# define TLS_INIT_TP(thrdescr, secondcall) \
  ({ void *_thrdescr = (thrdescr);                                \
     tcbhead_t *_head = _thrdescr;                                \
     union user_desc_init _segdescr;                                    \
     int _result;                                           \
                                                            \
     _head->tcb = _thrdescr;                                      \
     /* For now the thread descriptor is at the same address.  */       \
     _head->self = _thrdescr;                                     \
     /* New syscall handling support.  */                         \
     INIT_SYSINFO;                                                \
                                                            \
     /* The 'entry_number' field.  Let the kernel pick a value.  */           \
     if (secondcall)                                              \
       _segdescr.vals[0] = TLS_GET_GS () >> 3;                          \
     else                                                   \
       _segdescr.vals[0] = -1;                                          \
     /* The 'base_addr' field.  Pointer to the TCB.  */                       \
     _segdescr.vals[1] = (unsigned long int) _thrdescr;                       \
     /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */            \
     _segdescr.vals[2] = 0xfffff;                                 \
     /* Collapsed value of the bitfield:                          \
        .seg_32bit = 1                                      \
        .contents = 0                                             \
        .read_exec_only = 0                                       \
        .limit_in_pages = 1                                       \
        .seg_not_present = 0                                      \
        .useable = 1 */                                     \
     _segdescr.vals[3] = 0x51;                                          \
                                                            \
     /* Install the TLS.  */                                      \
     asm volatile (TLS_LOAD_EBX                                         \
               "int $0x80\n\t"                                    \
               TLS_LOAD_EBX                                       \
               : "=a" (_result), "=m" (_segdescr.desc.entry_number)           \
               : "0" (__NR_set_thread_area),                      \
                 TLS_EBX_ARG (&_segdescr.desc), "m" (_segdescr.desc));    \
                                                            \
     if (_result == 0)                                            \
       /* We know the index in the GDT, now load the segment register.        \
        The use of the GDT is described by the value 3 in the lower           \
        three bits of the segment descriptor value.                     \
                                                            \
        Note that we have to do this even if the numeric value of       \
        the descriptor does not change.  Loading the segment register         \
        causes the segment information from the GDT to be loaded        \
        which is necessary since we have changed it.   */               \
       TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                \
                                                            \
     _result == 0 ? NULL                                          \
     : "set_thread_area failed when setting up thread-local storage\n"; })


/* Return the address of the dtv for the current thread.  */
# define THREAD_DTV() \
  ({ struct pthread *__pd;                                        \
     THREAD_GETMEM (__pd, header.dtv); })


/* Return the thread descriptor for the current thread.

   The contained asm must *not* be marked volatile since otherwise
   assignments like
        pthread_descr self = thread_self();
   do not get optimized away.  */
# define THREAD_SELF \
  ({ struct pthread *__self;                                      \
     asm ("movl %%gs:%c1,%0" : "=r" (__self)                            \
        : "i" (offsetof (struct pthread, header.self)));                \
     __self;})

/* Magic for libthread_db to know how to do THREAD_SELF.  */
# define DB_THREAD_SELF \
  REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
  REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */


/* Read member of the thread descriptor directly.  */
# define THREAD_GETMEM(descr, member) \
  ({ __typeof (descr->member) __value;                                  \
     if (sizeof (__value) == 1)                                         \
       asm volatile ("movb %%gs:%P2,%b0"                          \
                 : "=q" (__value)                                 \
                 : "0" (0), "i" (offsetof (struct pthread, member)));     \
     else if (sizeof (__value) == 4)                                    \
       asm volatile ("movl %%gs:%P1,%0"                                 \
                 : "=r" (__value)                                 \
                 : "i" (offsetof (struct pthread, member)));            \
     else                                                   \
       {                                                    \
       if (sizeof (__value) != 8)                                 \
         /* There should not be any value with a size other than 1,           \
            4 or 8.  */                                     \
         abort ();                                                \
                                                            \
       asm volatile ("movl %%gs:%P1,%%eax\n\t"                    \
                   "movl %%gs:%P2,%%edx"                          \
                   : "=A" (__value)                               \
                   : "i" (offsetof (struct pthread, member)),           \
                   "i" (offsetof (struct pthread, member) + 4));        \
       }                                                    \
     __value; })


/* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
# define THREAD_GETMEM_NC(descr, member, idx) \
  ({ __typeof (descr->member[0]) __value;                         \
     if (sizeof (__value) == 1)                                         \
       asm volatile ("movb %%gs:%P2(%3),%b0"                            \
                 : "=q" (__value)                                 \
                 : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
                 "r" (idx));                                \
     else if (sizeof (__value) == 4)                                    \
       asm volatile ("movl %%gs:%P1(,%2,4),%0"                          \
                 : "=r" (__value)                                 \
                 : "i" (offsetof (struct pthread, member[0])),          \
                   "r" (idx));                                    \
     else                                                   \
       {                                                    \
       if (sizeof (__value) != 8)                                 \
         /* There should not be any value with a size other than 1,           \
            4 or 8.  */                                     \
         abort ();                                                \
                                                            \
       asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                  \
                  "movl %%gs:4+%P1(,%2,8),%%edx"                        \
                  : "=&A" (__value)                         \
                  : "i" (offsetof (struct pthread, member[0])),         \
                    "r" (idx));                                   \
       }                                                    \
     __value; })


/* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
# define THREAD_SETMEM(descr, member, value) \
  ({ if (sizeof (descr->member) == 1)                                   \
       asm volatile ("movb %b0,%%gs:%P1" :                              \
                 : "iq" (value),                                  \
                   "i" (offsetof (struct pthread, member)));            \
     else if (sizeof (descr->member) == 4)                              \
       asm volatile ("movl %0,%%gs:%P1" :                         \
                 : "ir" (value),                                  \
                   "i" (offsetof (struct pthread, member)));            \
     else                                                   \
       {                                                    \
       if (sizeof (descr->member) != 8)                           \
         /* There should not be any value with a size other than 1,           \
            4 or 8.  */                                     \
         abort ();                                                \
                                                            \
       asm volatile ("movl %%eax,%%gs:%P1\n\t"                    \
                   "movl %%edx,%%gs:%P2" :                              \
                   : "A" (value),                                 \
                   "i" (offsetof (struct pthread, member)),       \
                   "i" (offsetof (struct pthread, member) + 4));        \
       }})


/* Set member of the thread descriptor directly.  */
# define THREAD_SETMEM_NC(descr, member, idx, value) \
  ({ if (sizeof (descr->member[0]) == 1)                          \
       asm volatile ("movb %b0,%%gs:%P1(%2)" :                          \
                 : "iq" (value),                                  \
                   "i" (offsetof (struct pthread, member)),             \
                   "r" (idx));                                    \
     else if (sizeof (descr->member[0]) == 4)                           \
       asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                        \
                 : "ir" (value),                                  \
                   "i" (offsetof (struct pthread, member)),             \
                   "r" (idx));                                    \
     else                                                   \
       {                                                    \
       if (sizeof (descr->member[0]) != 8)                              \
         /* There should not be any value with a size other than 1,           \
            4 or 8.  */                                     \
         abort ();                                                \
                                                            \
       asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                   \
                   "movl %%edx,%%gs:4+%P1(,%2,8)" :                     \
                   : "A" (value),                                 \
                   "i" (offsetof (struct pthread, member)),       \
                   "r" (idx));                                    \
       }})


/* Atomic compare and exchange on TLS, returning old value.  */
#define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
  ({ __typeof (descr->member) __ret;                                    \
     __typeof (oldval) __old = (oldval);                          \
     if (sizeof (descr->member) == 4)                                   \
       asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                \
                 : "=a" (__ret)                                   \
                 : "0" (__old), "r" (newval),                     \
                   "i" (offsetof (struct pthread, member)));            \
     else                                                   \
       /* Not necessary for other sizes in the moment.  */              \
       abort ();                                            \
     __ret; })


/* Atomic set bit.  */
#define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
  (void) ({ if (sizeof ((descr)->member) == 4)                          \
            asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                \
                      :: "i" (offsetof (struct pthread, member)),       \
                         "ir" (1 << (bit)));                      \
          else                                              \
            /* Not necessary for other sizes in the moment.  */         \
            abort (); })


/* Call the user-provided thread function.  */
#define CALL_THREAD_FCT(descr) \
  ({ void *__res;                                           \
     int __ignore1, __ignore2;                                          \
     asm volatile ("pushl %%gs:%P4\n\t"                                 \
               "call *%%gs:%P3\n\t"                               \
               "addl $4, %%esp"                                   \
               : "=a" (__res), "=c" (__ignore1), "=d" (__ignore2)       \
               : "i" (offsetof (struct pthread, start_routine)),        \
                 "i" (offsetof (struct pthread, arg)));                 \
     __res; })


#endif /* __ASSEMBLER__ */

#endif      /* tls.h */

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