1/* Definition for thread-local data handling. nptl/x86_64 version.
2 Copyright (C) 2002-2020 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. */
36typedef struct
37{
38 int i[4];
39} __128bits;
40
41
42typedef 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#ifndef LOCK_PREFIX
103# ifdef UP
104# define LOCK_PREFIX /* nothing */
105# else
106# define LOCK_PREFIX "lock;"
107# endif
108#endif
109
110/* This is the size of the initial TCB. Can't be just sizeof (tcbhead_t),
111 because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
112 struct pthread even when not linked with -lpthread. */
113# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
114
115/* Alignment requirements for the initial TCB. */
116# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
117
118/* This is the size of the TCB. */
119# define TLS_TCB_SIZE sizeof (struct pthread)
120
121/* Alignment requirements for the TCB. */
122# define TLS_TCB_ALIGN __alignof__ (struct pthread)
123
124/* The TCB can have any size and the memory following the address the
125 thread pointer points to is unspecified. Allocate the TCB there. */
126# define TLS_TCB_AT_TP 1
127# define TLS_DTV_AT_TP 0
128
129/* Get the thread descriptor definition. */
130# include <nptl/descr.h>
131
132
133/* Install the dtv pointer. The pointer passed is to the element with
134 index -1 which contain the length. */
135# define INSTALL_DTV(descr, dtvp) \
136 ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
137
138/* Install new dtv for current thread. */
139# define INSTALL_NEW_DTV(dtvp) \
140 ({ struct pthread *__pd; \
141 THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
142
143/* Return dtv of given thread descriptor. */
144# define GET_DTV(descr) \
145 (((tcbhead_t *) (descr))->dtv)
146
147
148/* Code to initially initialize the thread pointer. This might need
149 special attention since 'errno' is not yet available and if the
150 operation can cause a failure 'errno' must not be touched.
151
152 We have to make the syscall for both uses of the macro since the
153 address might be (and probably is) different. */
154# define TLS_INIT_TP(thrdescr) \
155 ({ void *_thrdescr = (thrdescr); \
156 tcbhead_t *_head = _thrdescr; \
157 int _result; \
158 \
159 _head->tcb = _thrdescr; \
160 /* For now the thread descriptor is at the same address. */ \
161 _head->self = _thrdescr; \
162 \
163 /* It is a simple syscall to set the %fs value for the thread. */ \
164 asm volatile ("syscall" \
165 : "=a" (_result) \
166 : "0" ((unsigned long int) __NR_arch_prctl), \
167 "D" ((unsigned long int) ARCH_SET_FS), \
168 "S" (_thrdescr) \
169 : "memory", "cc", "r11", "cx"); \
170 \
171 _result ? "cannot set %fs base address for thread-local storage" : 0; \
172 })
173
174# define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd)
175
176
177/* Return the address of the dtv for the current thread. */
178# define THREAD_DTV() \
179 ({ struct pthread *__pd; \
180 THREAD_GETMEM (__pd, header.dtv); })
181
182
183/* Return the thread descriptor for the current thread.
184
185 The contained asm must *not* be marked volatile since otherwise
186 assignments like
187 pthread_descr self = thread_self();
188 do not get optimized away. */
189# define THREAD_SELF \
190 ({ struct pthread *__self; \
191 asm ("mov %%fs:%c1,%0" : "=r" (__self) \
192 : "i" (offsetof (struct pthread, header.self))); \
193 __self;})
194
195/* Magic for libthread_db to know how to do THREAD_SELF. */
196# define DB_THREAD_SELF_INCLUDE <sys/reg.h> /* For the FS constant. */
197# define DB_THREAD_SELF CONST_THREAD_AREA (64, FS)
198
199/* Read member of the thread descriptor directly. */
200# define THREAD_GETMEM(descr, member) \
201 ({ __typeof (descr->member) __value; \
202 _Static_assert (sizeof (__value) == 1 \
203 || sizeof (__value) == 4 \
204 || sizeof (__value) == 8, \
205 "size of per-thread data"); \
206 if (sizeof (__value) == 1) \
207 asm volatile ("movb %%fs:%P2,%b0" \
208 : "=q" (__value) \
209 : "0" (0), "i" (offsetof (struct pthread, member))); \
210 else if (sizeof (__value) == 4) \
211 asm volatile ("movl %%fs:%P1,%0" \
212 : "=r" (__value) \
213 : "i" (offsetof (struct pthread, member))); \
214 else /* 8 */ \
215 { \
216 asm volatile ("movq %%fs:%P1,%q0" \
217 : "=r" (__value) \
218 : "i" (offsetof (struct pthread, member))); \
219 } \
220 __value; })
221
222
223/* Same as THREAD_GETMEM, but the member offset can be non-constant. */
224# define THREAD_GETMEM_NC(descr, member, idx) \
225 ({ __typeof (descr->member[0]) __value; \
226 _Static_assert (sizeof (__value) == 1 \
227 || sizeof (__value) == 4 \
228 || sizeof (__value) == 8, \
229 "size of per-thread data"); \
230 if (sizeof (__value) == 1) \
231 asm volatile ("movb %%fs:%P2(%q3),%b0" \
232 : "=q" (__value) \
233 : "0" (0), "i" (offsetof (struct pthread, member[0])), \
234 "r" (idx)); \
235 else if (sizeof (__value) == 4) \
236 asm volatile ("movl %%fs:%P1(,%q2,4),%0" \
237 : "=r" (__value) \
238 : "i" (offsetof (struct pthread, member[0])), "r" (idx));\
239 else /* 8 */ \
240 { \
241 asm volatile ("movq %%fs:%P1(,%q2,8),%q0" \
242 : "=r" (__value) \
243 : "i" (offsetof (struct pthread, member[0])), \
244 "r" (idx)); \
245 } \
246 __value; })
247
248
249/* Loading addresses of objects on x86-64 needs to be treated special
250 when generating PIC code. */
251#ifdef __pic__
252# define IMM_MODE "nr"
253#else
254# define IMM_MODE "ir"
255#endif
256
257
258/* Set member of the thread descriptor directly. */
259# define THREAD_SETMEM(descr, member, value) \
260 ({ \
261 _Static_assert (sizeof (descr->member) == 1 \
262 || sizeof (descr->member) == 4 \
263 || sizeof (descr->member) == 8, \
264 "size of per-thread data"); \
265 if (sizeof (descr->member) == 1) \
266 asm volatile ("movb %b0,%%fs:%P1" : \
267 : "iq" (value), \
268 "i" (offsetof (struct pthread, member))); \
269 else if (sizeof (descr->member) == 4) \
270 asm volatile ("movl %0,%%fs:%P1" : \
271 : IMM_MODE (value), \
272 "i" (offsetof (struct pthread, member))); \
273 else /* 8 */ \
274 { \
275 asm volatile ("movq %q0,%%fs:%P1" : \
276 : IMM_MODE ((uint64_t) cast_to_integer (value)), \
277 "i" (offsetof (struct pthread, member))); \
278 }})
279
280
281/* Same as THREAD_SETMEM, but the member offset can be non-constant. */
282# define THREAD_SETMEM_NC(descr, member, idx, value) \
283 ({ \
284 _Static_assert (sizeof (descr->member[0]) == 1 \
285 || sizeof (descr->member[0]) == 4 \
286 || sizeof (descr->member[0]) == 8, \
287 "size of per-thread data"); \
288 if (sizeof (descr->member[0]) == 1) \
289 asm volatile ("movb %b0,%%fs:%P1(%q2)" : \
290 : "iq" (value), \
291 "i" (offsetof (struct pthread, member[0])), \
292 "r" (idx)); \
293 else if (sizeof (descr->member[0]) == 4) \
294 asm volatile ("movl %0,%%fs:%P1(,%q2,4)" : \
295 : IMM_MODE (value), \
296 "i" (offsetof (struct pthread, member[0])), \
297 "r" (idx)); \
298 else /* 8 */ \
299 { \
300 asm volatile ("movq %q0,%%fs:%P1(,%q2,8)" : \
301 : IMM_MODE ((uint64_t) cast_to_integer (value)), \
302 "i" (offsetof (struct pthread, member[0])), \
303 "r" (idx)); \
304 }})
305
306
307/* Set the stack guard field in TCB head. */
308# define THREAD_SET_STACK_GUARD(value) \
309 THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
310# define THREAD_COPY_STACK_GUARD(descr) \
311 ((descr)->header.stack_guard \
312 = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
313
314
315/* Set the pointer guard field in the TCB head. */
316# define THREAD_SET_POINTER_GUARD(value) \
317 THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
318# define THREAD_COPY_POINTER_GUARD(descr) \
319 ((descr)->header.pointer_guard \
320 = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
321
322
323/* Get and set the global scope generation counter in the TCB head. */
324# define THREAD_GSCOPE_IN_TCB 1
325# define THREAD_GSCOPE_FLAG_UNUSED 0
326# define THREAD_GSCOPE_FLAG_USED 1
327# define THREAD_GSCOPE_FLAG_WAIT 2
328# define THREAD_GSCOPE_RESET_FLAG() \
329 do \
330 { int __res; \
331 asm volatile ("xchgl %0, %%fs:%P1" \
332 : "=r" (__res) \
333 : "i" (offsetof (struct pthread, header.gscope_flag)), \
334 "0" (THREAD_GSCOPE_FLAG_UNUSED)); \
335 if (__res == THREAD_GSCOPE_FLAG_WAIT) \
336 lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \
337 } \
338 while (0)
339# define THREAD_GSCOPE_SET_FLAG() \
340 THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
341# define THREAD_GSCOPE_WAIT() \
342 GL(dl_wait_lookup_done) ()
343
344#endif /* __ASSEMBLER__ */
345
346#endif /* tls.h */
347