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/* Definitions for thread-local data handling. Hurd/i386 version.
Copyright (C) 2003, 2004 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 _I386_TLS_H
#define _I386_TLS_H
#if defined HAVE_TLS_SUPPORT
/* Some things really need not be machine-dependent. */
# include <sysdeps/mach/hurd/tls.h>
/* Indiciate that TLS support is available. */
# define USE_TLS 1
/* 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
# ifndef ASSEMBLER
/* Use i386-specific RPCs to arrange that %gs segment register prefix
addresses the TCB in each thread. */
# include <mach/i386/mach_i386.h>
# ifndef HAVE_I386_SET_GDT
# define __i386_set_gdt(thr, sel, desc) ((void) (thr), (void) (sel), (void) (desc), MIG_BAD_ID)
# endif
# include <errno.h>
# include <assert.h>
#define HURD_TLS_DESC_DECL(desc, tcb) \
struct descriptor desc = \
{ /* low word: */ \
0xffff /* limit 0..15 */ \
| (((unsigned int) (tcb)) << 16) /* base 0..15 */ \
, /* high word: */ \
((((unsigned int) (tcb)) >> 16) & 0xff) /* base 16..23 */ \
| ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */ \
| (0xf << 16) /* limit 16..19 */ \
| ((4 | 8) << 20) /* granularity = SZ_32|SZ_G */ \
| (((unsigned int) (tcb)) & 0xff000000) /* base 24..31 */ \
}
static inline const char * __attribute__ ((unused))
_hurd_tls_init (tcbhead_t *tcb, int secondcall)
{
HURD_TLS_DESC_DECL (desc, tcb);
if (!secondcall)
{
/* This field is used by TLS accesses to get our "thread pointer"
from the TLS point of view. */
tcb->tcb = tcb;
/* Cache our thread port. */
tcb->self = __mach_thread_self ();
/* Get the first available selector. */
int sel = -1;
error_t err = __i386_set_gdt (tcb->self, &sel, desc);
if (err == MIG_BAD_ID)
{
/* Old kernel, use a per-thread LDT. */
sel = 0x27;
err = __i386_set_ldt (tcb->self, sel, &desc, 1);
assert_perror (err);
if (err)
return "i386_set_ldt failed";
}
else if (err)
{
assert_perror (err); /* Separate from above with different line #. */
return "i386_set_gdt failed";
}
/* Now install the new selector. */
asm volatile ("mov %w0, %%gs" :: "q" (sel));
}
else
{
/* Fetch the selector set by the first call. */
int sel;
asm ("mov %%gs, %w0" : "=q" (sel));
if (__builtin_expect (sel, 0x50) & 4) /* LDT selector */
{
error_t err = __i386_set_ldt (tcb->self, sel, &desc, 1);
assert_perror (err);
if (err)
return "i386_set_ldt failed";
}
else
{
error_t err = __i386_set_gdt (tcb->self, &sel, desc);
assert_perror (err);
if (err)
return "i386_set_gdt failed";
}
}
return 0;
}
/* 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(descr, secondcall) \
_hurd_tls_init ((tcbhead_t *) (descr), (secondcall))
# define TLS_INIT_TP_EXPENSIVE 1
/* Return the TCB address of the current thread. */
# define THREAD_SELF \
({ tcbhead_t *__tcb; \
__asm__ ("movl %%gs:%c1,%0" : "=r" (__tcb) \
: "i" (offsetof (tcbhead_t, tcb))); \
__tcb;})
/* Install new dtv for current thread. */
# define INSTALL_NEW_DTV(dtvp) \
({ asm volatile ("movl %0,%%gs:%P1" \
: : "ir" (dtvp), "i" (offsetof (tcbhead_t, dtv))); })
/* Return the address of the dtv for the current thread. */
# define THREAD_DTV() \
({ dtv_t *_dtv; \
asm ("movl %%gs:%P1,%0" : "=q" (_dtv) : "i" (offsetof (tcbhead_t, dtv)));\
_dtv; })
/* Set up TLS in the new thread of a fork child, copying from our own. */
static inline error_t __attribute__ ((unused))
_hurd_tls_fork (thread_t child, struct machine_thread_state *state)
{
/* Fetch the selector set by _hurd_tls_init. */
int sel;
asm ("mov %%gs, %w0" : "=q" (sel));
if (sel == state->ds) /* _hurd_tls_init was never called. */
return 0;
tcbhead_t *const tcb = THREAD_SELF;
HURD_TLS_DESC_DECL (desc, tcb);
error_t err;
if (__builtin_expect (sel, 0x50) & 4) /* LDT selector */
err = __i386_set_ldt (child, sel, &desc, 1);
else
err = __i386_set_gdt (child, &sel, desc);
state->gs = sel;
return err;
}
# endif /* !ASSEMBLER */
#endif /* HAVE_TLS_SUPPORT */
#endif /* i386/tls.h */
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