1/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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 <http://www.gnu.org/licenses/>. */
18
19#ifndef _LOWLEVELLOCK_H
20#define _LOWLEVELLOCK_H 1
21
22#include <stap-probe.h>
23
24#ifndef __ASSEMBLER__
25# include <time.h>
26# include <sys/param.h>
27# include <bits/pthreadtypes.h>
28# include <kernel-features.h>
29# include <tcb-offsets.h>
30
31# ifndef LOCK_INSTR
32# ifdef UP
33# define LOCK_INSTR /* nothing */
34# else
35# define LOCK_INSTR "lock;"
36# endif
37# endif
38#else
39# ifndef LOCK
40# ifdef UP
41# define LOCK
42# else
43# define LOCK lock
44# endif
45# endif
46#endif
47
48#include <lowlevellock-futex.h>
49
50/* XXX Remove when no assembler code uses futexes anymore. */
51#define SYS_futex __NR_futex
52
53#ifndef __ASSEMBLER__
54
55/* Initializer for lock. */
56#define LLL_LOCK_INITIALIZER (0)
57#define LLL_LOCK_INITIALIZER_LOCKED (1)
58#define LLL_LOCK_INITIALIZER_WAITERS (2)
59
60
61/* NB: in the lll_trylock macro we simply return the value in %eax
62 after the cmpxchg instruction. In case the operation succeded this
63 value is zero. In case the operation failed, the cmpxchg instruction
64 has loaded the current value of the memory work which is guaranteed
65 to be nonzero. */
66#if !IS_IN (libc) || defined UP
67# define __lll_trylock_asm LOCK_INSTR "cmpxchgl %2, %1"
68#else
69# define __lll_trylock_asm "cmpl $0, __libc_multiple_threads(%%rip)\n\t" \
70 "je 0f\n\t" \
71 "lock; cmpxchgl %2, %1\n\t" \
72 "jmp 1f\n\t" \
73 "0:\tcmpxchgl %2, %1\n\t" \
74 "1:"
75#endif
76
77#define lll_trylock(futex) \
78 ({ int ret; \
79 __asm __volatile (__lll_trylock_asm \
80 : "=a" (ret), "=m" (futex) \
81 : "r" (LLL_LOCK_INITIALIZER_LOCKED), "m" (futex), \
82 "0" (LLL_LOCK_INITIALIZER) \
83 : "memory"); \
84 ret; })
85
86#define lll_cond_trylock(futex) \
87 ({ int ret; \
88 __asm __volatile (LOCK_INSTR "cmpxchgl %2, %1" \
89 : "=a" (ret), "=m" (futex) \
90 : "r" (LLL_LOCK_INITIALIZER_WAITERS), \
91 "m" (futex), "0" (LLL_LOCK_INITIALIZER) \
92 : "memory"); \
93 ret; })
94
95#if !IS_IN (libc) || defined UP
96# define __lll_lock_asm_start LOCK_INSTR "cmpxchgl %4, %2\n\t" \
97 "jz 24f\n\t"
98#else
99# define __lll_lock_asm_start "cmpl $0, __libc_multiple_threads(%%rip)\n\t" \
100 "je 0f\n\t" \
101 "lock; cmpxchgl %4, %2\n\t" \
102 "jnz 1f\n\t" \
103 "jmp 24f\n" \
104 "0:\tcmpxchgl %4, %2\n\t" \
105 "jz 24f\n\t"
106#endif
107
108#define lll_lock(futex, private) \
109 (void) \
110 ({ int ignore1, ignore2, ignore3; \
111 if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
112 __asm __volatile (__lll_lock_asm_start \
113 "1:\tlea %2, %%" RDI_LP "\n" \
114 "2:\tsub $128, %%" RSP_LP "\n" \
115 ".cfi_adjust_cfa_offset 128\n" \
116 "3:\tcallq __lll_lock_wait_private\n" \
117 "4:\tadd $128, %%" RSP_LP "\n" \
118 ".cfi_adjust_cfa_offset -128\n" \
119 "24:" \
120 : "=S" (ignore1), "=&D" (ignore2), "=m" (futex), \
121 "=a" (ignore3) \
122 : "0" (1), "m" (futex), "3" (0) \
123 : "cx", "r11", "cc", "memory"); \
124 else \
125 __asm __volatile (__lll_lock_asm_start \
126 "1:\tlea %2, %%" RDI_LP "\n" \
127 "2:\tsub $128, %%" RSP_LP "\n" \
128 ".cfi_adjust_cfa_offset 128\n" \
129 "3:\tcallq __lll_lock_wait\n" \
130 "4:\tadd $128, %%" RSP_LP "\n" \
131 ".cfi_adjust_cfa_offset -128\n" \
132 "24:" \
133 : "=S" (ignore1), "=D" (ignore2), "=m" (futex), \
134 "=a" (ignore3) \
135 : "1" (1), "m" (futex), "3" (0), "0" (private) \
136 : "cx", "r11", "cc", "memory"); \
137 }) \
138
139#define lll_cond_lock(futex, private) \
140 (void) \
141 ({ int ignore1, ignore2, ignore3; \
142 __asm __volatile (LOCK_INSTR "cmpxchgl %4, %2\n\t" \
143 "jz 24f\n" \
144 "1:\tlea %2, %%" RDI_LP "\n" \
145 "2:\tsub $128, %%" RSP_LP "\n" \
146 ".cfi_adjust_cfa_offset 128\n" \
147 "3:\tcallq __lll_lock_wait\n" \
148 "4:\tadd $128, %%" RSP_LP "\n" \
149 ".cfi_adjust_cfa_offset -128\n" \
150 "24:" \
151 : "=S" (ignore1), "=D" (ignore2), "=m" (futex), \
152 "=a" (ignore3) \
153 : "1" (2), "m" (futex), "3" (0), "0" (private) \
154 : "cx", "r11", "cc", "memory"); \
155 })
156
157#define lll_timedlock(futex, timeout, private) \
158 ({ int result, ignore1, ignore2, ignore3; \
159 __asm __volatile (LOCK_INSTR "cmpxchgl %1, %4\n\t" \
160 "jz 24f\n" \
161 "1:\tlea %4, %%" RDI_LP "\n" \
162 "0:\tmov %8, %%" RDX_LP "\n" \
163 "2:\tsub $128, %%" RSP_LP "\n" \
164 ".cfi_adjust_cfa_offset 128\n" \
165 "3:\tcallq __lll_timedlock_wait\n" \
166 "4:\tadd $128, %%" RSP_LP "\n" \
167 ".cfi_adjust_cfa_offset -128\n" \
168 "24:" \
169 : "=a" (result), "=D" (ignore1), "=S" (ignore2), \
170 "=&d" (ignore3), "=m" (futex) \
171 : "0" (0), "1" (1), "m" (futex), "m" (timeout), \
172 "2" (private) \
173 : "memory", "cx", "cc", "r10", "r11"); \
174 result; })
175
176extern int __lll_timedlock_elision (int *futex, short *adapt_count,
177 const struct timespec *timeout,
178 int private) attribute_hidden;
179
180#define lll_timedlock_elision(futex, adapt_count, timeout, private) \
181 __lll_timedlock_elision(&(futex), &(adapt_count), timeout, private)
182
183#if !IS_IN (libc) || defined UP
184# define __lll_unlock_asm_start LOCK_INSTR "decl %0\n\t" \
185 "je 24f\n\t"
186#else
187# define __lll_unlock_asm_start "cmpl $0, __libc_multiple_threads(%%rip)\n\t" \
188 "je 0f\n\t" \
189 "lock; decl %0\n\t" \
190 "jne 1f\n\t" \
191 "jmp 24f\n\t" \
192 "0:\tdecl %0\n\t" \
193 "je 24f\n\t"
194#endif
195
196#define lll_unlock(futex, private) \
197 (void) \
198 ({ int ignore; \
199 if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
200 __asm __volatile (__lll_unlock_asm_start \
201 "1:\tlea %0, %%" RDI_LP "\n" \
202 "2:\tsub $128, %%" RSP_LP "\n" \
203 ".cfi_adjust_cfa_offset 128\n" \
204 "3:\tcallq __lll_unlock_wake_private\n" \
205 "4:\tadd $128, %%" RSP_LP "\n" \
206 ".cfi_adjust_cfa_offset -128\n" \
207 "24:" \
208 : "=m" (futex), "=&D" (ignore) \
209 : "m" (futex) \
210 : "ax", "cx", "r11", "cc", "memory"); \
211 else \
212 __asm __volatile (__lll_unlock_asm_start \
213 "1:\tlea %0, %%" RDI_LP "\n" \
214 "2:\tsub $128, %%" RSP_LP "\n" \
215 ".cfi_adjust_cfa_offset 128\n" \
216 "3:\tcallq __lll_unlock_wake\n" \
217 "4:\tadd $128, %%" RSP_LP "\n" \
218 ".cfi_adjust_cfa_offset -128\n" \
219 "24:" \
220 : "=m" (futex), "=&D" (ignore) \
221 : "m" (futex), "S" (private) \
222 : "ax", "cx", "r11", "cc", "memory"); \
223 })
224
225#define lll_islocked(futex) \
226 (futex != LLL_LOCK_INITIALIZER)
227
228
229/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
230 wake-up when the clone terminates. The memory location contains the
231 thread ID while the clone is running and is reset to zero by the kernel
232 afterwards. The kernel up to version 3.16.3 does not use the private futex
233 operations for futex wake-up when the clone terminates. */
234#define lll_wait_tid(tid) \
235 do { \
236 __typeof (tid) __tid; \
237 while ((__tid = (tid)) != 0) \
238 lll_futex_wait (&(tid), __tid, LLL_SHARED);\
239 } while (0)
240
241extern int __lll_timedwait_tid (int *, const struct timespec *)
242 attribute_hidden;
243
244/* As lll_wait_tid, but with a timeout. If the timeout occurs then return
245 ETIMEDOUT. If ABSTIME is invalid, return EINVAL.
246 XXX Note that this differs from the generic version in that we do the
247 error checking here and not in __lll_timedwait_tid. */
248#define lll_timedwait_tid(tid, abstime) \
249 ({ \
250 int __result = 0; \
251 if ((tid) != 0) \
252 { \
253 if ((abstime)->tv_nsec < 0 || (abstime)->tv_nsec >= 1000000000) \
254 __result = EINVAL; \
255 else \
256 __result = __lll_timedwait_tid (&(tid), (abstime)); \
257 } \
258 __result; })
259
260extern int __lll_lock_elision (int *futex, short *adapt_count, int private)
261 attribute_hidden;
262
263extern int __lll_unlock_elision (int *lock, int private)
264 attribute_hidden;
265
266extern int __lll_trylock_elision (int *lock, short *adapt_count)
267 attribute_hidden;
268
269#define lll_lock_elision(futex, adapt_count, private) \
270 __lll_lock_elision (&(futex), &(adapt_count), private)
271#define lll_unlock_elision(futex, adapt_count, private) \
272 __lll_unlock_elision (&(futex), private)
273#define lll_trylock_elision(futex, adapt_count) \
274 __lll_trylock_elision (&(futex), &(adapt_count))
275
276#endif /* !__ASSEMBLER__ */
277
278#endif /* lowlevellock.h */
279