1 /* Definition for thread-local data handling. nptl/x86_64 version.
2 Copyright (C) 2002-2023 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 == 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 */