tls.h

glibc 2.9,最新版的C语言库函数

/* Definition for thread-local data handling.  nptl/i386 version.
   Copyright (C) 2002,2003,2004,2005,2006,2007 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 <stdbool.h>
# include <stddef.h>
# include <stdint.h>
# include <stdlib.h>
# include <list.h>
# include <sysdep.h>
# include <kernel-features.h>


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


typedef struct
{
  void *tcb;		/* Pointer to the TCB.  Not necessarily the
			   thread descriptor used by libpthread.  */
  dtv_t *dtv;
  void *self;		/* Pointer to the thread descriptor.  */
  int multiple_threads;
  uintptr_t sysinfo;
  uintptr_t stack_guard;
  uintptr_t pointer_guard;
  int gscope_flag;
#ifndef __ASSUME_PRIVATE_FUTEX
  int private_futex;
#endif
} 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

/* 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.  Can't be just sizeof (tcbhead_t),
   because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
   struct pthread even when not linked with -lpthread.  */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)

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

/* 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)

#define THREAD_SELF_SYSINFO	THREAD_GETMEM (THREAD_SELF, header.sysinfo)
#define THREAD_SYSINFO(pd)	((pd)->header.sysinfo)

/* 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 = GLRO(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),			      \