arch/sparc/vdso/vclock_gettime.c

   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 /* Disable profiling for userspace code: */
  16 #ifndef DISABLE_BRANCH_PROFILING
  17 #define DISABLE_BRANCH_PROFILING
  18 #endif
  19
  20 #include <linux/kernel.h>
  21 #include <linux/time.h>
  22 #include <linux/string.h>
  23 #include <asm/io.h>
  24 #include <asm/unistd.h>
  25 #include <asm/timex.h>
  26 #include <asm/clocksource.h>
  27 #include <asm/vvar.h>
  28
  29 #undef  TICK_PRIV_BIT
  30 #ifdef  CONFIG_SPARC64
  31 #define TICK_PRIV_BIT   (1UL << 63)
  32 #else
  33 #define TICK_PRIV_BIT   (1ULL << 63)
  34 #endif
  35
  36 #define SYSCALL_STRING                                                  \
  37         "ta     0x6d;"                                                  \
  38         "sub    %%g0, %%o0, %%o0;"                                      \
  39
  40 #define SYSCALL_CLOBBERS                                                \
  41         "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",                 \
  42         "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",           \
  43         "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",         \
  44         "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",         \
  45         "f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46",         \
  46         "f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62",         \
  47         "cc", "memory"
  48
  49 /*
  50  * Compute the vvar page's address in the process address space, and return it
  51  * as a pointer to the vvar_data.
  52  */
  53 static notrace noinline struct vvar_data *
  54 get_vvar_data(void)
  55 {
  56         unsigned long ret;
  57
  58         /*
  59          * vdso data page is the first vDSO page so grab the return address
  60          * and move up a page to get to the data page.
  61          */
  62         ret = (unsigned long)__builtin_return_address(0);
  63         ret &= ~(8192 - 1);
  64         ret -= 8192;
  65
  66         return (struct vvar_data *) ret;
  67 }
  68
  69 static notrace long
  70 vdso_fallback_gettime(long clock, struct timespec *ts)
  71 {
  72         register long num __asm__("g1") = __NR_clock_gettime;
  73         register long o0 __asm__("o0") = clock;
  74         register long o1 __asm__("o1") = (long) ts;
  75
  76         __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
  77                              "0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
  78         return o0;
  79 }
  80
  81 static notrace __always_inline long
  82 vdso_fallback_gettimeofday(struct timeval *tv, struct timezone *tz)
  83 {
  84         register long num __asm__("g1") = __NR_gettimeofday;
  85         register long o0 __asm__("o0") = (long) tv;
  86         register long o1 __asm__("o1") = (long) tz;
  87
  88         __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
  89                              "0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
  90         return o0;
  91 }
  92
  93 #ifdef  CONFIG_SPARC64
  94 static notrace noinline u64
  95 vread_tick(void) {
  96         u64     ret;
  97
  98         __asm__ __volatile__("rd        %%asr24, %0 \n"
  99                              ".section  .vread_tick_patch, \"ax\" \n"
 100                              "rd        %%tick, %0 \n"
 101                              ".previous \n"
 102                              : "=&r" (ret));
 103         return ret & ~TICK_PRIV_BIT;
 104 }
 105 #else
 106 static notrace noinline u64
 107 vread_tick(void)
 108 {
 109         unsigned int lo, hi;
 110
 111         __asm__ __volatile__("rd        %%asr24, %%g1\n\t"
 112                              "srlx      %%g1, 32, %1\n\t"
 113                              "srl       %%g1, 0, %0\n"
 114                              ".section  .vread_tick_patch, \"ax\" \n"
 115                              "rd        %%tick, %%g1\n"
 116                              ".previous \n"
 117                              : "=&r" (lo), "=&r" (hi)
 118                              :
 119                              : "g1");
 120         return lo | ((u64)hi << 32);
 121 }
 122 #endif
 123
 124 static notrace inline u64
 125 vgetsns(struct vvar_data *vvar)
 126 {
 127         u64 v;
 128         u64 cycles;
 129
 130         cycles = vread_tick();
 131         v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
 132         return v * vvar->clock.mult;
 133 }
 134
 135 static notrace noinline int
 136 do_realtime(struct vvar_data *vvar, struct timespec *ts)
 137 {
 138         unsigned long seq;
 139         u64 ns;
 140
 141         ts->tv_nsec = 0;
 142         do {
 143                 seq = vvar_read_begin(vvar);
 144                 ts->tv_sec = vvar->wall_time_sec;
 145                 ns = vvar->wall_time_snsec;
 146                 ns += vgetsns(vvar);
 147                 ns >>= vvar->clock.shift;
 148         } while (unlikely(vvar_read_retry(vvar, seq)));
 149
 150         timespec_add_ns(ts, ns);
 151
 152         return 0;
 153 }
 154
 155 static notrace noinline int
 156 do_monotonic(struct vvar_data *vvar, struct timespec *ts)
 157 {
 158         unsigned long seq;
 159         u64 ns;
 160
 161         ts->tv_nsec = 0;
 162         do {
 163                 seq = vvar_read_begin(vvar);
 164                 ts->tv_sec = vvar->monotonic_time_sec;
 165                 ns = vvar->monotonic_time_snsec;
 166                 ns += vgetsns(vvar);
 167                 ns >>= vvar->clock.shift;
 168         } while (unlikely(vvar_read_retry(vvar, seq)));
 169
 170         timespec_add_ns(ts, ns);
 171
 172         return 0;
 173 }
 174
 175 static notrace noinline int
 176 do_realtime_coarse(struct vvar_data *vvar, struct timespec *ts)
 177 {
 178         unsigned long seq;
 179
 180         do {
 181                 seq = vvar_read_begin(vvar);
 182                 ts->tv_sec = vvar->wall_time_coarse_sec;
 183                 ts->tv_nsec = vvar->wall_time_coarse_nsec;
 184         } while (unlikely(vvar_read_retry(vvar, seq)));
 185         return 0;
 186 }
 187
 188 static notrace noinline int
 189 do_monotonic_coarse(struct vvar_data *vvar, struct timespec *ts)
 190 {
 191         unsigned long seq;
 192
 193         do {
 194                 seq = vvar_read_begin(vvar);
 195                 ts->tv_sec = vvar->monotonic_time_coarse_sec;
 196                 ts->tv_nsec = vvar->monotonic_time_coarse_nsec;
 197         } while (unlikely(vvar_read_retry(vvar, seq)));
 198
 199         return 0;
 200 }
 201
 202 notrace int
 203 __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 204 {
 205         struct vvar_data *vvd = get_vvar_data();
 206
 207         switch (clock) {
 208         case CLOCK_REALTIME:
 209                 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
 210                         break;
 211                 return do_realtime(vvd, ts);
 212         case CLOCK_MONOTONIC:
 213                 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
 214                         break;
 215                 return do_monotonic(vvd, ts);
 216         case CLOCK_REALTIME_COARSE:
 217                 return do_realtime_coarse(vvd, ts);
 218         case CLOCK_MONOTONIC_COARSE:
 219                 return do_monotonic_coarse(vvd, ts);
 220         }
 221         /*
 222          * Unknown clock ID ? Fall back to the syscall.
 223          */
 224         return vdso_fallback_gettime(clock, ts);
 225 }
 226 int
 227 clock_gettime(clockid_t, struct timespec *)
 228         __attribute__((weak, alias("__vdso_clock_gettime")));
 229
 230 notrace int
 231 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 232 {
 233         struct vvar_data *vvd = get_vvar_data();
 234
 235         if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
 236                 if (likely(tv != NULL)) {
 237                         union tstv_t {
 238                                 struct timespec ts;
 239                                 struct timeval tv;
 240                         } *tstv = (union tstv_t *) tv;
 241                         do_realtime(vvd, &tstv->ts);
 242                         /*
 243                          * Assign before dividing to ensure that the division is
 244                          * done in the type of tv_usec, not tv_nsec.
 245                          *
 246                          * There cannot be > 1 billion usec in a second:
 247                          * do_realtime() has already distributed such overflow
 248                          * into tv_sec.  So we can assign it to an int safely.
 249                          */
 250                         tstv->tv.tv_usec = tstv->ts.tv_nsec;
 251                         tstv->tv.tv_usec /= 1000;
 252                 }
 253                 if (unlikely(tz != NULL)) {
 254                         /* Avoid memcpy. Some old compilers fail to inline it */
 255                         tz->tz_minuteswest = vvd->tz_minuteswest;
 256                         tz->tz_dsttime = vvd->tz_dsttime;
 257                 }
 258                 return 0;
 259         }
 260         return vdso_fallback_gettimeofday(tv, tz);
 261 }
 262 int
 263 gettimeofday(struct timeval *, struct timezone *)
 264         __attribute__((weak, alias("__vdso_gettimeofday")));