sysdeps/x86_64/nptl/tls.h

   1 /* Definition for thread-local data handling.  nptl/x86_64 version.
   2    Copyright (C) 2002-2021 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _TLS_H
  20 #define _TLS_H  1
  21
  22 #ifndef __ASSEMBLER__
  23 # include <asm/prctl.h> /* For ARCH_SET_FS.  */
  24 # include <stdbool.h>
  25 # include <stddef.h>
  26 # include <stdint.h>
  27 # include <stdlib.h>
  28 # include <sysdep.h>
  29 # include <libc-pointer-arith.h> /* For cast_to_integer.  */
  30 # include <kernel-features.h>
  31 # include <dl-dtv.h>
  32
  33 /* Replacement type for __m128 since this file is included by ld.so,
  34    which is compiled with -mno-sse.  It must not change the alignment
  35    of rtld_savespace_sse.  */
  36 typedef struct
  37 {
  38   int i[4];
  39 } __128bits;
  40
  41
  42 typedef struct
  43 {
  44   void *tcb;            /* Pointer to the TCB.  Not necessarily the
  45                            thread descriptor used by libpthread.  */
  46   dtv_t *dtv;
  47   void *self;           /* Pointer to the thread descriptor.  */
  48   int multiple_threads;
  49   int gscope_flag;
  50   uintptr_t sysinfo;
  51   uintptr_t stack_guard;
  52   uintptr_t pointer_guard;
  53   unsigned long int unused_vgetcpu_cache[2];
  54   /* Bit 0: X86_FEATURE_1_IBT.
  55      Bit 1: X86_FEATURE_1_SHSTK.
  56    */
  57   unsigned int feature_1;
  58   int __glibc_unused1;
  59   /* Reservation of some values for the TM ABI.  */
  60   void *__private_tm[4];
  61   /* GCC split stack support.  */
  62   void *__private_ss;
  63   /* The lowest address of shadow stack,  */
  64   unsigned long long int ssp_base;
  65   /* Must be kept even if it is no longer used by glibc since programs,
  66      like AddressSanitizer, depend on the size of tcbhead_t.  */
  67   __128bits __glibc_unused2[8][4] __attribute__ ((aligned (32)));
  68
  69   void *__padding[8];
  70 } tcbhead_t;
  71
  72 # ifdef __ILP32__
  73 /* morestack.S in libgcc uses offset 0x40 to access __private_ss,   */
  74 _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x40,
  75                 "offset of __private_ss != 0x40");
  76 /* NB: ssp_base used to be "long int __glibc_reserved2", which was
  77    changed from 32 bits to 64 bits.  Make sure that the offset of the
  78    next field, __glibc_unused2, is unchanged.  */
  79 _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x60,
  80                 "offset of __glibc_unused2 != 0x60");
  81 # else
  82 /* morestack.S in libgcc uses offset 0x70 to access __private_ss,   */
  83 _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70,
  84                 "offset of __private_ss != 0x70");
  85 _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
  86                 "offset of __glibc_unused2 != 0x80");
  87 # endif
  88
  89 #else /* __ASSEMBLER__ */
  90 # include <tcb-offsets.h>
  91 #endif
  92
  93
  94 /* Alignment requirement for the stack.  */
  95 #define STACK_ALIGN     16
  96
  97
  98 #ifndef __ASSEMBLER__
  99 /* Get system call information.  */
 100 # include <sysdep.h>
 101
 102 #define LOCK_PREFIX "lock;"
 103
 104 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
 105    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
 106    struct pthread even when not linked with -lpthread.  */
 107 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
 108
 109 /* Alignment requirements for the initial TCB.  */
 110 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
 111
 112 /* This is the size of the TCB.  */
 113 # define TLS_TCB_SIZE sizeof (struct pthread)
 114
 115 /* Alignment requirements for the TCB.  */
 116 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 117
 118 /* The TCB can have any size and the memory following the address the
 119    thread pointer points to is unspecified.  Allocate the TCB there.  */
 120 # define TLS_TCB_AT_TP  1
 121 # define TLS_DTV_AT_TP  0
 122
 123 /* Get the thread descriptor definition.  */
 124 # include <nptl/descr.h>
 125
 126
 127 /* Install the dtv pointer.  The pointer passed is to the element with
 128    index -1 which contain the length.  */
 129 # define INSTALL_DTV(descr, dtvp) \
 130   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 131
 132 /* Install new dtv for current thread.  */
 133 # define INSTALL_NEW_DTV(dtvp) \
 134   ({ struct pthread *__pd;                                                    \
 135      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 136
 137 /* Return dtv of given thread descriptor.  */
 138 # define GET_DTV(descr) \
 139   (((tcbhead_t *) (descr))->dtv)
 140
 141
 142 /* Code to initially initialize the thread pointer.  This might need
 143    special attention since 'errno' is not yet available and if the
 144    operation can cause a failure 'errno' must not be touched.
 145
 146    We have to make the syscall for both uses of the macro since the
 147    address might be (and probably is) different.  */
 148 # define TLS_INIT_TP(thrdescr) \
 149   ({ void *_thrdescr = (thrdescr);                                            \
 150      tcbhead_t *_head = _thrdescr;                                            \
 151      int _result;                                                             \
 152                                                                               \
 153      _head->tcb = _thrdescr;                                                  \
 154      /* For now the thread descriptor is at the same address.  */             \
 155      _head->self = _thrdescr;                                                 \
 156                                                                               \
 157      /* It is a simple syscall to set the %fs value for the thread.  */       \
 158      asm volatile ("syscall"                                                  \
 159                    : "=a" (_result)                                           \
 160                    : "0" ((unsigned long int) __NR_arch_prctl),               \
 161                      "D" ((unsigned long int) ARCH_SET_FS),                   \
 162                      "S" (_thrdescr)                                          \
 163                    : "memory", "cc", "r11", "cx");                            \
 164                                                                               \
 165     _result ? "cannot set %fs base address for thread-local storage" : 0;     \
 166   })
 167
 168 # define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd)
 169
 170
 171 /* Return the address of the dtv for the current thread.  */
 172 # define THREAD_DTV() \
 173   ({ struct pthread *__pd;                                                    \
 174      THREAD_GETMEM (__pd, header.dtv); })
 175
 176
 177 /* Return the thread descriptor for the current thread.
 178
 179    The contained asm must *not* be marked volatile since otherwise
 180    assignments like
 181         pthread_descr self = thread_self();
 182    do not get optimized away.  */
 183 # if __GNUC_PREREQ (6, 0)
 184 #  define THREAD_SELF \
 185   (*(struct pthread *__seg_fs *) offsetof (struct pthread, header.self))
 186 # else
 187 #  define THREAD_SELF \
 188   ({ struct pthread *__self;                                                  \
 189      asm ("mov %%fs:%c1,%0" : "=r" (__self)                                   \
 190           : "i" (offsetof (struct pthread, header.self)));                    \
 191      __self;})
 192 # endif
 193
 194 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 195 # define DB_THREAD_SELF_INCLUDE  <sys/reg.h> /* For the FS constant.  */
 196 # define DB_THREAD_SELF CONST_THREAD_AREA (64, FS)
 197
 198 # include <tcb-access.h>
 199
 200 /* Set the stack guard field in TCB head.  */
 201 # define THREAD_SET_STACK_GUARD(value) \
 202     THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 203 # define THREAD_COPY_STACK_GUARD(descr) \
 204     ((descr)->header.stack_guard                                              \
 205      = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 206
 207
 208 /* Set the pointer guard field in the TCB head.  */
 209 # define THREAD_SET_POINTER_GUARD(value) \
 210   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 211 # define THREAD_COPY_POINTER_GUARD(descr) \
 212   ((descr)->header.pointer_guard                                              \
 213    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 214
 215
 216 /* Get and set the global scope generation counter in the TCB head.  */
 217 # define THREAD_GSCOPE_FLAG_UNUSED 0
 218 # define THREAD_GSCOPE_FLAG_USED   1
 219 # define THREAD_GSCOPE_FLAG_WAIT   2
 220 # define THREAD_GSCOPE_RESET_FLAG() \
 221   do                                                                          \
 222     { int __res;                                                              \
 223       asm volatile ("xchgl %0, %%fs:%P1"                                      \
 224                     : "=r" (__res)                                            \
 225                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 226                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 227       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 228         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 229     }                                                                         \
 230   while (0)
 231 # define THREAD_GSCOPE_SET_FLAG() \
 232   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 233
 234 #endif /* __ASSEMBLER__ */
 235
 236 #endif  /* tls.h */