1 /* Definition for thread-local data handling. nptl/x86_64 version. 2 Copyright (C) 2002-2022 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 /* This is the size of the TCB. */ 110 # define TLS_TCB_SIZE sizeof (struct pthread) 111 112 /* The TCB can have any size and the memory following the address the 113 thread pointer points to is unspecified. Allocate the TCB there. */ 114 # define TLS_TCB_AT_TP 1 115 # define TLS_DTV_AT_TP 0 116 117 /* Get the thread descriptor definition. */ 118 # include <nptl/descr.h> 119 120 121 /* Install the dtv pointer. The pointer passed is to the element with 122 index -1 which contain the length. */ 123 # define INSTALL_DTV(descr, dtvp) \ 124 ((tcbhead_t *) (descr))->dtv = (dtvp) + 1 125 126 /* Install new dtv for current thread. */ 127 # define INSTALL_NEW_DTV(dtvp) \ 128 ({ struct pthread *__pd; \ 129 THREAD_SETMEM (__pd, header.dtv, (dtvp)); }) 130 131 /* Return dtv of given thread descriptor. */ 132 # define GET_DTV(descr) \ 133 (((tcbhead_t *) (descr))->dtv) 134 135 136 /* Code to initially initialize the thread pointer. This might need 137 special attention since 'errno' is not yet available and if the 138 operation can cause a failure 'errno' must not be touched. 139 140 We have to make the syscall for both uses of the macro since the 141 address might be (and probably is) different. */ 142 # define TLS_INIT_TP(thrdescr) \ 143 ({ void *_thrdescr = (thrdescr); \ 144 tcbhead_t *_head = _thrdescr; \ 145 int _result; \ 146 \ 147 _head->tcb = _thrdescr; \ 148 /* For now the thread descriptor is at the same address. */ \ 149 _head->self = _thrdescr; \ 150 \ 151 /* It is a simple syscall to set the %fs value for the thread. */ \ 152 asm volatile ("syscall" \ 153 : "=a" (_result) \ 154 : "0" ((unsigned long int) __NR_arch_prctl), \ 155 "D" ((unsigned long int) ARCH_SET_FS), \ 156 "S" (_thrdescr) \ 157 : "memory", "cc", "r11", "cx"); \ 158 \ 159 _result ? "cannot set %fs base address for thread-local storage" : 0; \ 160 }) 161 162 # define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd) 163 164 165 /* Return the address of the dtv for the current thread. */ 166 # define THREAD_DTV() \ 167 ({ struct pthread *__pd; \ 168 THREAD_GETMEM (__pd, header.dtv); }) 169 170 171 /* Return the thread descriptor for the current thread. 172 173 The contained asm must *not* be marked volatile since otherwise 174 assignments like 175 pthread_descr self = thread_self(); 176 do not get optimized away. */ 177 # if __GNUC_PREREQ (6, 0) 178 # define THREAD_SELF \ 179 (*(struct pthread *__seg_fs *) offsetof (struct pthread, header.self)) 180 # else 181 # define THREAD_SELF \ 182 ({ struct pthread *__self; \ 183 asm ("mov %%fs:%c1,%0" : "=r" (__self) \ 184 : "i" (offsetof (struct pthread, header.self))); \ 185 __self;}) 186 # endif 187 188 /* Magic for libthread_db to know how to do THREAD_SELF. */ 189 # define DB_THREAD_SELF_INCLUDE <sys/reg.h> /* For the FS constant. */ 190 # define DB_THREAD_SELF CONST_THREAD_AREA (64, FS) 191 192 # include <tcb-access.h> 193 194 /* Set the stack guard field in TCB head. */ 195 # define THREAD_SET_STACK_GUARD(value) \ 196 THREAD_SETMEM (THREAD_SELF, header.stack_guard, value) 197 # define THREAD_COPY_STACK_GUARD(descr) \ 198 ((descr)->header.stack_guard \ 199 = THREAD_GETMEM (THREAD_SELF, header.stack_guard)) 200 201 202 /* Set the pointer guard field in the TCB head. */ 203 # define THREAD_SET_POINTER_GUARD(value) \ 204 THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value) 205 # define THREAD_COPY_POINTER_GUARD(descr) \ 206 ((descr)->header.pointer_guard \ 207 = THREAD_GETMEM (THREAD_SELF, header.pointer_guard)) 208 209 210 /* Get and set the global scope generation counter in the TCB head. */ 211 # define THREAD_GSCOPE_FLAG_UNUSED 0 212 # define THREAD_GSCOPE_FLAG_USED 1 213 # define THREAD_GSCOPE_FLAG_WAIT 2 214 # define THREAD_GSCOPE_RESET_FLAG() \ 215 do \ 216 { int __res; \ 217 asm volatile ("xchgl %0, %%fs:%P1" \ 218 : "=r" (__res) \ 219 : "i" (offsetof (struct pthread, header.gscope_flag)), \ 220 "0" (THREAD_GSCOPE_FLAG_UNUSED)); \ 221 if (__res == THREAD_GSCOPE_FLAG_WAIT) \ 222 lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \ 223 } \ 224 while (0) 225 # define THREAD_GSCOPE_SET_FLAG() \ 226 THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED) 227 228 #endif /* __ASSEMBLER__ */ 229 230 #endif /* tls.h */ 231