libgo/runtime/runtime.c

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 #include <signal.h>
   6 #include <unistd.h>
   7
   8 #include "config.h"
   9
  10 #include "runtime.h"
  11 #include "arch.h"
  12 #include "array.h"
  13
  14 enum {
  15         maxround = sizeof(uintptr),
  16 };
  17
  18 // Keep a cached value to make gotraceback fast,
  19 // since we call it on every call to gentraceback.
  20 // The cached value is a uint32 in which the low bit
  21 // is the "crash" setting and the top 31 bits are the
  22 // gotraceback value.
  23 static uint32 traceback_cache = ~(uint32)0;
  24
  25 // The GOTRACEBACK environment variable controls the
  26 // behavior of a Go program that is crashing and exiting.
  27 //      GOTRACEBACK=0   suppress all tracebacks
  28 //      GOTRACEBACK=1   default behavior - show tracebacks but exclude runtime frames
  29 //      GOTRACEBACK=2   show tracebacks including runtime frames
  30 //      GOTRACEBACK=crash   show tracebacks including runtime frames, then crash (core dump etc)
  31 int32
  32 runtime_gotraceback(bool *crash)
  33 {
  34         const byte *p;
  35         uint32 x;
  36
  37         if(crash != nil)
  38                 *crash = false;
  39         if(runtime_m()->traceback != 0)
  40                 return runtime_m()->traceback;
  41         x = runtime_atomicload(&traceback_cache);
  42         if(x == ~(uint32)0) {
  43                 p = runtime_getenv("GOTRACEBACK");
  44                 if(p == nil)
  45                         p = (const byte*)"";
  46                 if(p[0] == '\0')
  47                         x = 1<<1;
  48                 else if(runtime_strcmp((const char *)p, "crash") == 0)
  49                         x = (2<<1) | 1;
  50                 else
  51                         x = runtime_atoi(p)<<1;
  52                 runtime_atomicstore(&traceback_cache, x);
  53         }
  54         if(crash != nil)
  55                 *crash = x&1;
  56         return x>>1;
  57 }
  58
  59 static int32    argc;
  60 static byte**   argv;
  61
  62 extern Slice os_Args __asm__ (GOSYM_PREFIX "os.Args");
  63 extern Slice syscall_Envs __asm__ (GOSYM_PREFIX "syscall.Envs");
  64
  65 void (*runtime_sysargs)(int32, uint8**);
  66
  67 void
  68 runtime_args(int32 c, byte **v)
  69 {
  70         argc = c;
  71         argv = v;
  72         if(runtime_sysargs != nil)
  73                 runtime_sysargs(c, v);
  74 }
  75
  76 byte*
  77 runtime_progname()
  78 {
  79   return argc == 0 ? nil : argv[0];
  80 }
  81
  82 void
  83 runtime_goargs(void)
  84 {
  85         String *s;
  86         int32 i;
  87
  88         // for windows implementation see "os" package
  89         if(Windows)
  90                 return;
  91
  92         s = runtime_malloc(argc*sizeof s[0]);
  93         for(i=0; i<argc; i++)
  94                 s[i] = runtime_gostringnocopy((const byte*)argv[i]);
  95         os_Args.__values = (void*)s;
  96         os_Args.__count = argc;
  97         os_Args.__capacity = argc;
  98 }
  99
 100 void
 101 runtime_goenvs_unix(void)
 102 {
 103         String *s;
 104         int32 i, n;
 105
 106         for(n=0; argv[argc+1+n] != 0; n++)
 107                 ;
 108
 109         s = runtime_malloc(n*sizeof s[0]);
 110         for(i=0; i<n; i++)
 111                 s[i] = runtime_gostringnocopy(argv[argc+1+i]);
 112         syscall_Envs.__values = (void*)s;
 113         syscall_Envs.__count = n;
 114         syscall_Envs.__capacity = n;
 115
 116         traceback_cache = ~(uint32)0;
 117 }
 118
 119 int32
 120 runtime_atoi(const byte *p)
 121 {
 122         int32 n;
 123
 124         n = 0;
 125         while('0' <= *p && *p <= '9')
 126                 n = n*10 + *p++ - '0';
 127         return n;
 128 }
 129
 130 static struct root_list runtime_roots =
 131 { nil,
 132   { { &syscall_Envs, sizeof syscall_Envs },
 133     { &os_Args, sizeof os_Args },
 134     { nil, 0 } },
 135 };
 136
 137 static void
 138 TestAtomic64(void)
 139 {
 140         uint64 z64, x64;
 141
 142         z64 = 42;
 143         x64 = 0;
 144         PREFETCH(&z64);
 145         if(runtime_cas64(&z64, x64, 1))
 146                 runtime_throw("cas64 failed");
 147         if(x64 != 0)
 148                 runtime_throw("cas64 failed");
 149         x64 = 42;
 150         if(!runtime_cas64(&z64, x64, 1))
 151                 runtime_throw("cas64 failed");
 152         if(x64 != 42 || z64 != 1)
 153                 runtime_throw("cas64 failed");
 154         if(runtime_atomicload64(&z64) != 1)
 155                 runtime_throw("load64 failed");
 156         runtime_atomicstore64(&z64, (1ull<<40)+1);
 157         if(runtime_atomicload64(&z64) != (1ull<<40)+1)
 158                 runtime_throw("store64 failed");
 159         if(runtime_xadd64(&z64, (1ull<<40)+1) != (2ull<<40)+2)
 160                 runtime_throw("xadd64 failed");
 161         if(runtime_atomicload64(&z64) != (2ull<<40)+2)
 162                 runtime_throw("xadd64 failed");
 163         if(runtime_xchg64(&z64, (3ull<<40)+3) != (2ull<<40)+2)
 164                 runtime_throw("xchg64 failed");
 165         if(runtime_atomicload64(&z64) != (3ull<<40)+3)
 166                 runtime_throw("xchg64 failed");
 167 }
 168
 169 void
 170 runtime_check(void)
 171 {
 172         __go_register_gc_roots(&runtime_roots);
 173
 174         TestAtomic64();
 175 }
 176
 177 uint32
 178 runtime_fastrand1(void)
 179 {
 180         M *m;
 181         uint32 x;
 182
 183         m = runtime_m();
 184         x = m->fastrand;
 185         x += x;
 186         if(x & 0x80000000L)
 187                 x ^= 0x88888eefUL;
 188         m->fastrand = x;
 189         return x;
 190 }
 191
 192 int64
 193 runtime_cputicks(void)
 194 {
 195 #if defined(__386__) || defined(__x86_64__)
 196   uint32 low, high;
 197   asm("rdtsc" : "=a" (low), "=d" (high));
 198   return (int64)(((uint64)high << 32) | (uint64)low);
 199 #else
 200   // FIXME: implement for other processors.
 201   return 0;
 202 #endif
 203 }
 204
 205 bool
 206 runtime_showframe(String s, bool current)
 207 {
 208         static int32 traceback = -1;
 209
 210         if(current && runtime_m()->throwing > 0)
 211                 return 1;
 212         if(traceback < 0)
 213                 traceback = runtime_gotraceback(nil);
 214         return traceback > 1 || (__builtin_memchr(s.str, '.', s.len) != nil && __builtin_memcmp(s.str, "runtime.", 7) != 0);
 215 }
 216
 217 static Lock ticksLock;
 218 static int64 ticks;
 219
 220 int64
 221 runtime_tickspersecond(void)
 222 {
 223         int64 res, t0, t1, c0, c1;
 224
 225         res = (int64)runtime_atomicload64((uint64*)&ticks);
 226         if(res != 0)
 227                 return ticks;
 228         runtime_lock(&ticksLock);
 229         res = ticks;
 230         if(res == 0) {
 231                 t0 = runtime_nanotime();
 232                 c0 = runtime_cputicks();
 233                 runtime_usleep(100*1000);
 234                 t1 = runtime_nanotime();
 235                 c1 = runtime_cputicks();
 236                 if(t1 == t0)
 237                         t1++;
 238                 res = (c1-c0)*1000*1000*1000/(t1-t0);
 239                 if(res == 0)
 240                         res++;
 241                 runtime_atomicstore64((uint64*)&ticks, res);
 242         }
 243         runtime_unlock(&ticksLock);
 244         return res;
 245 }
 246
 247 // Called to initialize a new m (including the bootstrap m).
 248 // Called on the parent thread (main thread in case of bootstrap), can allocate memory.
 249 void
 250 runtime_mpreinit(M *mp)
 251 {
 252         mp->gsignal = runtime_malg(32*1024, &mp->gsignalstack, &mp->gsignalstacksize);  // OS X wants >=8K, Linux >=2K
 253 }
 254
 255 // Called to initialize a new m (including the bootstrap m).
 256 // Called on the new thread, can not allocate memory.
 257 void
 258 runtime_minit(void)
 259 {
 260         M* m;
 261         sigset_t sigs;
 262
 263         // Initialize signal handling.
 264         m = runtime_m();
 265         runtime_signalstack(m->gsignalstack, m->gsignalstacksize);
 266         if (sigemptyset(&sigs) != 0)
 267                 runtime_throw("sigemptyset");
 268         pthread_sigmask(SIG_SETMASK, &sigs, nil);
 269 }
 270
 271 // Called from dropm to undo the effect of an minit.
 272 void
 273 runtime_unminit(void)
 274 {
 275         runtime_signalstack(nil, 0);
 276 }
 277
 278
 279 void
 280 runtime_signalstack(byte *p, int32 n)
 281 {
 282         stack_t st;
 283
 284         st.ss_sp = p;
 285         st.ss_size = n;
 286         st.ss_flags = 0;
 287         if(p == nil)
 288                 st.ss_flags = SS_DISABLE;
 289         if(sigaltstack(&st, nil) < 0)
 290                 *(int *)0xf1 = 0xf1;
 291 }
 292
 293 DebugVars       runtime_debug;
 294
 295 static struct {
 296         const char* name;
 297         int32*  value;
 298 } dbgvar[] = {
 299         {"allocfreetrace", &runtime_debug.allocfreetrace},
 300         {"efence", &runtime_debug.efence},
 301         {"gctrace", &runtime_debug.gctrace},
 302         {"gcdead", &runtime_debug.gcdead},
 303         {"scheddetail", &runtime_debug.scheddetail},
 304         {"schedtrace", &runtime_debug.schedtrace},
 305 };
 306
 307 void
 308 runtime_parsedebugvars(void)
 309 {
 310         const byte *p;
 311         intgo i, n;
 312
 313         p = runtime_getenv("GODEBUG");
 314         if(p == nil)
 315                 return;
 316         for(;;) {
 317                 for(i=0; i<(intgo)nelem(dbgvar); i++) {
 318                         n = runtime_findnull((const byte*)dbgvar[i].name);
 319                         if(runtime_mcmp(p, dbgvar[i].name, n) == 0 && p[n] == '=')
 320                                 *dbgvar[i].value = runtime_atoi(p+n+1);
 321                 }
 322                 p = (const byte *)runtime_strstr((const char *)p, ",");
 323                 if(p == nil)
 324                         break;
 325                 p++;
 326         }
 327 }
 328
 329 // Poor mans 64-bit division.
 330 // This is a very special function, do not use it if you are not sure what you are doing.
 331 // int64 division is lowered into _divv() call on 386, which does not fit into nosplit functions.
 332 // Handles overflow in a time-specific manner.
 333 int32
 334 runtime_timediv(int64 v, int32 div, int32 *rem)
 335 {
 336         int32 res, bit;
 337
 338         if(v >= (int64)div*0x7fffffffLL) {
 339                 if(rem != nil)
 340                         *rem = 0;
 341                 return 0x7fffffff;
 342         }
 343         res = 0;
 344         for(bit = 30; bit >= 0; bit--) {
 345                 if(v >= ((int64)div<<bit)) {
 346                         v = v - ((int64)div<<bit);
 347                         res += 1<<bit;
 348                 }
 349         }
 350         if(rem != nil)
 351                 *rem = v;
 352         return res;
 353 }
 354
 355 // Setting the max stack size doesn't really do anything for gccgo.
 356
 357 uintptr runtime_maxstacksize = 1<<20; // enough until runtime.main sets it for real
 358
 359 void memclrBytes(Slice)
 360      __asm__ (GOSYM_PREFIX "runtime.memclrBytes");
 361
 362 void
 363 memclrBytes(Slice s)
 364 {
 365         runtime_memclr(s.__values, s.__count);
 366 }