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.
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.
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.
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/>. */
23 # include <asm/prctl.h> /* For ARCH_SET_FS. */
29 # include <libc-pointer-arith.h> /* For cast_to_integer. */
30 # include <kernel-features.h>
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. */
44 void *tcb
; /* Pointer to the TCB. Not necessarily the
45 thread descriptor used by libpthread. */
47 void *self
; /* Pointer to the thread descriptor. */
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.
57 unsigned int feature_1
;
59 /* Reservation of some values for the TM ABI. */
60 void *__private_tm
[4];
61 /* GCC split stack support. */
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)));
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");
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");
89 #else /* __ASSEMBLER__ */
90 # include <tcb-offsets.h>
94 /* Alignment requirement for the stack. */
95 #define STACK_ALIGN 16
99 /* Get system call information. */
102 #define LOCK_PREFIX "lock;"
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)
109 /* Alignment requirements for the initial TCB. */
110 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
112 /* This is the size of the TCB. */
113 # define TLS_TCB_SIZE sizeof (struct pthread)
115 /* Alignment requirements for the TCB. */
116 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
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
123 /* Get the thread descriptor definition. */
124 # include <nptl/descr.h>
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
132 /* Install new dtv for current thread. */
133 # define INSTALL_NEW_DTV(dtvp) \
134 ({ struct pthread *__pd; \
135 THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
137 /* Return dtv of given thread descriptor. */
138 # define GET_DTV(descr) \
139 (((tcbhead_t *) (descr))->dtv)
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.
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; \
153 _head->tcb = _thrdescr; \
154 /* For now the thread descriptor is at the same address. */ \
155 _head->self = _thrdescr; \
157 /* It is a simple syscall to set the %fs value for the thread. */ \
158 asm volatile ("syscall" \
160 : "0" ((unsigned long int) __NR_arch_prctl), \
161 "D" ((unsigned long int) ARCH_SET_FS), \
163 : "memory", "cc", "r11", "cx"); \
165 _result ? "cannot set %fs base address for thread-local storage" : 0; \
168 # define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd)
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); })
177 /* Return the thread descriptor for the current thread.
179 The contained asm must *not* be marked volatile since otherwise
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))
187 # define THREAD_SELF \
188 ({ struct pthread *__self; \
189 asm ("mov %%fs:%c1,%0" : "=r" (__self) \
190 : "i" (offsetof (struct pthread, header.self))); \
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)
198 # include <tcb-access.h>
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))
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))
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() \
223 asm volatile ("xchgl %0, %%fs:%P1" \
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); \
231 # define THREAD_GSCOPE_SET_FLAG() \
232 THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
234 #endif /* __ASSEMBLER__ */