sysdeps/mach/hurd/i386/tls.h

   1 /* Definitions for thread-local data handling.  Hurd/i386 version.
   2    Copyright (C) 2003-2016 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _I386_TLS_H
  20 #define _I386_TLS_H
  21
  22
  23 /* Some things really need not be machine-dependent.  */
  24 #include <sysdeps/mach/hurd/tls.h>
  25
  26
  27 #ifndef __ASSEMBLER__
  28 # include <dl-dtv.h>
  29
  30 /* Type of the TCB.  */
  31 typedef struct
  32 {
  33   void *tcb;                    /* Points to this structure.  */
  34   dtv_t *dtv;                   /* Vector of pointers to TLS data.  */
  35   thread_t self;                /* This thread's control port.  */
  36   int multiple_threads;
  37   uintptr_t sysinfo;
  38   uintptr_t stack_guard;
  39   uintptr_t pointer_guard;
  40   int gscope_flag;
  41   int private_futex;
  42   /* Reservation of some values for the TM ABI.  */
  43   void *__private_tm[4];
  44   /* GCC split stack support.  */
  45   void *__private_ss;
  46 } tcbhead_t;
  47 #endif
  48
  49
  50 /* The TCB can have any size and the memory following the address the
  51    thread pointer points to is unspecified.  Allocate the TCB there.  */
  52 #define TLS_TCB_AT_TP   1
  53 #define TLS_DTV_AT_TP   0
  54
  55 #ifndef __ASSEMBLER__
  56
  57 /* Use i386-specific RPCs to arrange that %gs segment register prefix
  58    addresses the TCB in each thread.  */
  59 # include <mach/i386/mach_i386.h>
  60
  61 # ifndef HAVE_I386_SET_GDT
  62 #  define __i386_set_gdt(thr, sel, desc) ((void) (thr), (void) (sel), (void) (desc), MIG_BAD_ID)
  63 # endif
  64
  65 # include <errno.h>
  66 # include <assert.h>
  67
  68 # define HURD_TLS_DESC_DECL(desc, tcb)                                        \
  69   struct descriptor desc =                                                    \
  70     {                           /* low word: */                               \
  71       0xffff                    /* limit 0..15 */                             \
  72       | (((unsigned int) (tcb)) << 16) /* base 0..15 */                       \
  73       ,                         /* high word: */                              \
  74       ((((unsigned int) (tcb)) >> 16) & 0xff) /* base 16..23 */               \
  75       | ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */  \
  76       | (0xf << 16)             /* limit 16..19 */                            \
  77       | ((4 | 8) << 20)         /* granularity = SZ_32|SZ_G */                \
  78       | (((unsigned int) (tcb)) & 0xff000000) /* base 24..31 */               \
  79     }
  80
  81
  82 static inline const char * __attribute__ ((unused))
  83 _hurd_tls_init (tcbhead_t *tcb)
  84 {
  85   HURD_TLS_DESC_DECL (desc, tcb);
  86
  87   /* This field is used by TLS accesses to get our "thread pointer"
  88      from the TLS point of view.  */
  89   tcb->tcb = tcb;
  90
  91   /* Cache our thread port.  */
  92   tcb->self = __mach_thread_self ();
  93
  94   /* Get the first available selector.  */
  95   int sel = -1;
  96   error_t err = __i386_set_gdt (tcb->self, &sel, desc);
  97   if (err == MIG_BAD_ID)
  98     {
  99       /* Old kernel, use a per-thread LDT.  */
 100       sel = 0x27;
 101       err = __i386_set_ldt (tcb->self, sel, &desc, 1);
 102       assert_perror (err);
 103       if (err)
 104         return "i386_set_ldt failed";
 105     }
 106   else if (err)
 107     {
 108       assert_perror (err); /* Separate from above with different line #. */
 109       return "i386_set_gdt failed";
 110     }
 111
 112   /* Now install the new selector.  */
 113   asm volatile ("mov %w0, %%gs" :: "q" (sel));
 114
 115   return 0;
 116 }
 117
 118 /* Code to initially initialize the thread pointer.  This might need
 119    special attention since 'errno' is not yet available and if the
 120    operation can cause a failure 'errno' must not be touched.  */
 121 # define TLS_INIT_TP(descr) \
 122     _hurd_tls_init ((tcbhead_t *) (descr))
 123
 124 /* Return the TCB address of the current thread.  */
 125 # define THREAD_SELF                                                          \
 126   ({ tcbhead_t *__tcb;                                                        \
 127      __asm__ ("movl %%gs:%c1,%0" : "=r" (__tcb)                               \
 128               : "i" (offsetof (tcbhead_t, tcb)));                             \
 129      __tcb;})
 130
 131 /* Install new dtv for current thread.  */
 132 # define INSTALL_NEW_DTV(dtvp)                                                \
 133   ({ asm volatile ("movl %0,%%gs:%P1"                                         \
 134                    : : "ir" (dtvp), "i" (offsetof (tcbhead_t, dtv))); })
 135
 136 /* Return the address of the dtv for the current thread.  */
 137 # define THREAD_DTV()                                                         \
 138   ({ dtv_t *_dtv;                                                             \
 139      asm ("movl %%gs:%P1,%0" : "=q" (_dtv) : "i" (offsetof (tcbhead_t, dtv)));\
 140      _dtv; })
 141
 142 # include <mach/machine/thread_status.h>
 143
 144 /* Set up TLS in the new thread of a fork child, copying from our own.  */
 145 static inline error_t __attribute__ ((unused))
 146 _hurd_tls_fork (thread_t child, struct i386_thread_state *state)
 147 {
 148   /* Fetch the selector set by _hurd_tls_init.  */
 149   int sel;
 150   asm ("mov %%gs, %w0" : "=q" (sel) : "0" (0));
 151   if (sel == state->ds)         /* _hurd_tls_init was never called.  */
 152     return 0;
 153
 154   tcbhead_t *const tcb = THREAD_SELF;
 155   HURD_TLS_DESC_DECL (desc, tcb);
 156   error_t err;
 157
 158   if (__builtin_expect (sel, 0x50) & 4) /* LDT selector */
 159     err = __i386_set_ldt (child, sel, &desc, 1);
 160   else
 161     err = __i386_set_gdt (child, &sel, desc);
 162
 163   state->gs = sel;
 164   return err;
 165 }
 166
 167 #endif  /* !__ASSEMBLER__ */
 168
 169 #endif  /* i386/tls.h */