1 /* 2 * Copyright 2006 Andi Kleen, SUSE Labs. 3 * Subject to the GNU Public License, v.2 4 * 5 * Fast user context implementation of clock_gettime, gettimeofday, and time. 6 * 7 * The code should have no internal unresolved relocations. 8 * Check with readelf after changing. 9 * Also alternative() doesn't work. 10 */ 11 /* 12 * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved. 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/time.h> 17 #include <linux/string.h> 18 #include <asm/io.h> 19 #include <asm/unistd.h> 20 #include <asm/timex.h> 21 #include <asm/clocksource.h> 22 #include <asm/vvar.h> 23 24 #ifdef CONFIG_SPARC64 25 #define SYSCALL_STRING \ 26 "ta 0x6d;" \ 27 "bcs,a 1f;" \ 28 " sub %%g0, %%o0, %%o0;" \ 29 "1:" 30 #else 31 #define SYSCALL_STRING \ 32 "ta 0x10;" \ 33 "bcs,a 1f;" \ 34 " sub %%g0, %%o0, %%o0;" \ 35 "1:" 36 #endif 37 38 #define SYSCALL_CLOBBERS \ 39 "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \ 40 "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15", \ 41 "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23", \ 42 "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31", \ 43 "f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46", \ 44 "f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62", \ 45 "cc", "memory" 46 47 /* 48 * Compute the vvar page's address in the process address space, and return it 49 * as a pointer to the vvar_data. 50 */ 51 notrace static __always_inline struct vvar_data *get_vvar_data(void) 52 { 53 unsigned long ret; 54 55 /* 56 * vdso data page is the first vDSO page so grab the PC 57 * and move up a page to get to the data page. 58 */ 59 __asm__("rd %%pc, %0" : "=r" (ret)); 60 ret &= ~(8192 - 1); 61 ret -= 8192; 62 63 return (struct vvar_data *) ret; 64 } 65 66 notrace static long vdso_fallback_gettime(long clock, struct timespec *ts) 67 { 68 register long num __asm__("g1") = __NR_clock_gettime; 69 register long o0 __asm__("o0") = clock; 70 register long o1 __asm__("o1") = (long) ts; 71 72 __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num), 73 "0" (o0), "r" (o1) : SYSCALL_CLOBBERS); 74 return o0; 75 } 76 77 notrace static long vdso_fallback_gettimeofday(struct timeval *tv, struct timezone *tz) 78 { 79 register long num __asm__("g1") = __NR_gettimeofday; 80 register long o0 __asm__("o0") = (long) tv; 81 register long o1 __asm__("o1") = (long) tz; 82 83 __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num), 84 "0" (o0), "r" (o1) : SYSCALL_CLOBBERS); 85 return o0; 86 } 87 88 #ifdef CONFIG_SPARC64 89 notrace static __always_inline u64 vread_tick(void) 90 { 91 u64 ret; 92 93 __asm__ __volatile__("rd %%tick, %0" : "=r" (ret)); 94 return ret; 95 } 96 97 notrace static __always_inline u64 vread_tick_stick(void) 98 { 99 u64 ret; 100 101 __asm__ __volatile__("rd %%asr24, %0" : "=r" (ret)); 102 return ret; 103 } 104 #else 105 notrace static __always_inline u64 vread_tick(void) 106 { 107 register unsigned long long ret asm("o4"); 108 109 __asm__ __volatile__("rd %%tick, %L0\n\t" 110 "srlx %L0, 32, %H0" 111 : "=r" (ret)); 112 return ret; 113 } 114 115 notrace static __always_inline u64 vread_tick_stick(void) 116 { 117 register unsigned long long ret asm("o4"); 118 119 __asm__ __volatile__("rd %%asr24, %L0\n\t" 120 "srlx %L0, 32, %H0" 121 : "=r" (ret)); 122 return ret; 123 } 124 #endif 125 126 notrace static __always_inline u64 vgetsns(struct vvar_data *vvar) 127 { 128 u64 v; 129 u64 cycles; 130 131 cycles = vread_tick(); 132 v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask; 133 return v * vvar->clock.mult; 134 } 135 136 notrace static __always_inline u64 vgetsns_stick(struct vvar_data *vvar) 137 { 138 u64 v; 139 u64 cycles; 140 141 cycles = vread_tick_stick(); 142 v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask; 143 return v * vvar->clock.mult; 144 } 145 146 notrace static __always_inline int do_realtime(struct vvar_data *vvar, 147 struct timespec *ts) 148 { 149 unsigned long seq; 150 u64 ns; 151 152 do { 153 seq = vvar_read_begin(vvar); 154 ts->tv_sec = vvar->wall_time_sec; 155 ns = vvar->wall_time_snsec; 156 ns += vgetsns(vvar); 157 ns >>= vvar->clock.shift; 158 } while (unlikely(vvar_read_retry(vvar, seq))); 159 160 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); 161 ts->tv_nsec = ns; 162 163 return 0; 164 } 165 166 notrace static __always_inline int do_realtime_stick(struct vvar_data *vvar, 167 struct timespec *ts) 168 { 169 unsigned long seq; 170 u64 ns; 171 172 do { 173 seq = vvar_read_begin(vvar); 174 ts->tv_sec = vvar->wall_time_sec; 175 ns = vvar->wall_time_snsec; 176 ns += vgetsns_stick(vvar); 177 ns >>= vvar->clock.shift; 178 } while (unlikely(vvar_read_retry(vvar, seq))); 179 180 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); 181 ts->tv_nsec = ns; 182 183 return 0; 184 } 185 186 notrace static __always_inline int do_monotonic(struct vvar_data *vvar, 187 struct timespec *ts) 188 { 189 unsigned long seq; 190 u64 ns; 191 192 do { 193 seq = vvar_read_begin(vvar); 194 ts->tv_sec = vvar->monotonic_time_sec; 195 ns = vvar->monotonic_time_snsec; 196 ns += vgetsns(vvar); 197 ns >>= vvar->clock.shift; 198 } while (unlikely(vvar_read_retry(vvar, seq))); 199 200 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); 201 ts->tv_nsec = ns; 202 203 return 0; 204 } 205 206 notrace static __always_inline int do_monotonic_stick(struct vvar_data *vvar, 207 struct timespec *ts) 208 { 209 unsigned long seq; 210 u64 ns; 211 212 do { 213 seq = vvar_read_begin(vvar); 214 ts->tv_sec = vvar->monotonic_time_sec; 215 ns = vvar->monotonic_time_snsec; 216 ns += vgetsns_stick(vvar); 217 ns >>= vvar->clock.shift; 218 } while (unlikely(vvar_read_retry(vvar, seq))); 219 220 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); 221 ts->tv_nsec = ns; 222 223 return 0; 224 } 225 226 notrace static int do_realtime_coarse(struct vvar_data *vvar, 227 struct timespec *ts) 228 { 229 unsigned long seq; 230 231 do { 232 seq = vvar_read_begin(vvar); 233 ts->tv_sec = vvar->wall_time_coarse_sec; 234 ts->tv_nsec = vvar->wall_time_coarse_nsec; 235 } while (unlikely(vvar_read_retry(vvar, seq))); 236 return 0; 237 } 238 239 notrace static int do_monotonic_coarse(struct vvar_data *vvar, 240 struct timespec *ts) 241 { 242 unsigned long seq; 243 244 do { 245 seq = vvar_read_begin(vvar); 246 ts->tv_sec = vvar->monotonic_time_coarse_sec; 247 ts->tv_nsec = vvar->monotonic_time_coarse_nsec; 248 } while (unlikely(vvar_read_retry(vvar, seq))); 249 250 return 0; 251 } 252 253 notrace int 254 __vdso_clock_gettime(clockid_t clock, struct timespec *ts) 255 { 256 struct vvar_data *vvd = get_vvar_data(); 257 258 switch (clock) { 259 case CLOCK_REALTIME: 260 if (unlikely(vvd->vclock_mode == VCLOCK_NONE)) 261 break; 262 return do_realtime(vvd, ts); 263 case CLOCK_MONOTONIC: 264 if (unlikely(vvd->vclock_mode == VCLOCK_NONE)) 265 break; 266 return do_monotonic(vvd, ts); 267 case CLOCK_REALTIME_COARSE: 268 return do_realtime_coarse(vvd, ts); 269 case CLOCK_MONOTONIC_COARSE: 270 return do_monotonic_coarse(vvd, ts); 271 } 272 /* 273 * Unknown clock ID ? Fall back to the syscall. 274 */ 275 return vdso_fallback_gettime(clock, ts); 276 } 277 int 278 clock_gettime(clockid_t, struct timespec *) 279 __attribute__((weak, alias("__vdso_clock_gettime"))); 280 281 notrace int 282 __vdso_clock_gettime_stick(clockid_t clock, struct timespec *ts) 283 { 284 struct vvar_data *vvd = get_vvar_data(); 285 286 switch (clock) { 287 case CLOCK_REALTIME: 288 if (unlikely(vvd->vclock_mode == VCLOCK_NONE)) 289 break; 290 return do_realtime_stick(vvd, ts); 291 case CLOCK_MONOTONIC: 292 if (unlikely(vvd->vclock_mode == VCLOCK_NONE)) 293 break; 294 return do_monotonic_stick(vvd, ts); 295 case CLOCK_REALTIME_COARSE: 296 return do_realtime_coarse(vvd, ts); 297 case CLOCK_MONOTONIC_COARSE: 298 return do_monotonic_coarse(vvd, ts); 299 } 300 /* 301 * Unknown clock ID ? Fall back to the syscall. 302 */ 303 return vdso_fallback_gettime(clock, ts); 304 } 305 306 notrace int 307 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) 308 { 309 struct vvar_data *vvd = get_vvar_data(); 310 311 if (likely(vvd->vclock_mode != VCLOCK_NONE)) { 312 if (likely(tv != NULL)) { 313 union tstv_t { 314 struct timespec ts; 315 struct timeval tv; 316 } *tstv = (union tstv_t *) tv; 317 do_realtime(vvd, &tstv->ts); 318 /* 319 * Assign before dividing to ensure that the division is 320 * done in the type of tv_usec, not tv_nsec. 321 * 322 * There cannot be > 1 billion usec in a second: 323 * do_realtime() has already distributed such overflow 324 * into tv_sec. So we can assign it to an int safely. 325 */ 326 tstv->tv.tv_usec = tstv->ts.tv_nsec; 327 tstv->tv.tv_usec /= 1000; 328 } 329 if (unlikely(tz != NULL)) { 330 /* Avoid memcpy. Some old compilers fail to inline it */ 331 tz->tz_minuteswest = vvd->tz_minuteswest; 332 tz->tz_dsttime = vvd->tz_dsttime; 333 } 334 return 0; 335 } 336 return vdso_fallback_gettimeofday(tv, tz); 337 } 338 int 339 gettimeofday(struct timeval *, struct timezone *) 340 __attribute__((weak, alias("__vdso_gettimeofday"))); 341 342 notrace int 343 __vdso_gettimeofday_stick(struct timeval *tv, struct timezone *tz) 344 { 345 struct vvar_data *vvd = get_vvar_data(); 346 347 if (likely(vvd->vclock_mode != VCLOCK_NONE)) { 348 if (likely(tv != NULL)) { 349 union tstv_t { 350 struct timespec ts; 351 struct timeval tv; 352 } *tstv = (union tstv_t *) tv; 353 do_realtime_stick(vvd, &tstv->ts); 354 /* 355 * Assign before dividing to ensure that the division is 356 * done in the type of tv_usec, not tv_nsec. 357 * 358 * There cannot be > 1 billion usec in a second: 359 * do_realtime() has already distributed such overflow 360 * into tv_sec. So we can assign it to an int safely. 361 */ 362 tstv->tv.tv_usec = tstv->ts.tv_nsec; 363 tstv->tv.tv_usec /= 1000; 364 } 365 if (unlikely(tz != NULL)) { 366 /* Avoid memcpy. Some old compilers fail to inline it */ 367 tz->tz_minuteswest = vvd->tz_minuteswest; 368 tz->tz_dsttime = vvd->tz_dsttime; 369 } 370 return 0; 371 } 372 return vdso_fallback_gettimeofday(tv, tz); 373 } 374