libgo/runtime/runtime_c.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 <errno.h>
   6 #include <signal.h>
   7 #include <unistd.h>
   8
   9 #if defined(__i386__) || defined(__x86_64__)
  10 #include <cpuid.h>
  11 #endif
  12
  13 #ifdef __linux__
  14 #include <syscall.h>
  15 #endif
  16
  17 #include "config.h"
  18
  19 #include "runtime.h"
  20 #include "arch.h"
  21 #include "array.h"
  22
  23 int32
  24 runtime_atoi(const byte *p, intgo len)
  25 {
  26         int32 n;
  27
  28         n = 0;
  29         while(len > 0 && '0' <= *p && *p <= '9') {
  30                 n = n*10 + *p++ - '0';
  31                 len--;
  32         }
  33         return n;
  34 }
  35
  36 // A random number from the GNU/Linux auxv array.
  37 static uint32 randomNumber;
  38
  39 // Set the random number from Go code.
  40
  41 void
  42 setRandomNumber(uint32 r)
  43 {
  44         randomNumber = r;
  45 }
  46
  47 #if defined(__i386__) || defined(__x86_64__) || defined (__s390__) || defined (__s390x__)
  48
  49 // When cputicks is just asm instructions, skip the split stack
  50 // prologue for speed.
  51
  52 int64 runtime_cputicks(void) __attribute__((no_split_stack));
  53
  54 #endif
  55
  56 // Whether the processor supports SSE2.
  57 #if defined (__i386__)
  58 static _Bool hasSSE2;
  59
  60 // Force appropriate CPU level so that we can call the lfence/mfence
  61 // builtins.
  62
  63 #pragma GCC push_options
  64 #pragma GCC target("sse2")
  65
  66 #elif defined(__x86_64__)
  67 #define hasSSE2 true
  68 #endif
  69
  70 #if defined(__i386__) || defined(__x86_64__)
  71 // Whether to use lfence, as opposed to mfence.
  72 // Set based on cpuid.
  73 static _Bool lfenceBeforeRdtsc;
  74 #endif // defined(__i386__) || defined(__x86_64__)
  75
  76 int64
  77 runtime_cputicks(void)
  78 {
  79 #if defined(__i386__) || defined(__x86_64__)
  80   if (hasSSE2) {
  81     if (lfenceBeforeRdtsc) {
  82       __builtin_ia32_lfence();
  83     } else {
  84       __builtin_ia32_mfence();
  85     }
  86   }
  87   return __builtin_ia32_rdtsc();
  88 #elif defined (__s390__) || defined (__s390x__)
  89   uint64 clock = 0;
  90   /* stckf may not write the return variable in case of a clock error, so make
  91      it read-write to prevent that the initialisation is optimised out.
  92      Note: Targets below z9-109 will crash when executing store clock fast, i.e.
  93      we don't support Go for machines older than that.  */
  94   asm volatile(".insn s,0xb27c0000,%0" /* stckf */ : "+Q" (clock) : : "cc" );
  95   return (int64)clock;
  96 #else
  97   // Currently cputicks() is used in blocking profiler and to seed runtime·fastrand().
  98   // runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
  99   // randomNumber provides better seeding of fastrand.
 100   return runtime_nanotime() + randomNumber;
 101 #endif
 102 }
 103
 104 #if defined(__i386__)
 105 #pragma GCC pop_options
 106 #endif
 107
 108 void
 109 runtime_signalstack(byte *p, uintptr n)
 110 {
 111         stack_t st;
 112
 113         st.ss_sp = p;
 114         st.ss_size = n;
 115         st.ss_flags = 0;
 116         if(p == nil)
 117                 st.ss_flags = SS_DISABLE;
 118         if(sigaltstack(&st, nil) < 0)
 119                 *(int *)0xf1 = 0xf1;
 120 }
 121
 122 int32 go_open(char *, int32, int32)
 123   __asm__ (GOSYM_PREFIX "runtime.open");
 124
 125 int32
 126 go_open(char *name, int32 mode, int32 perm)
 127 {
 128   return runtime_open(name, mode, perm);
 129 }
 130
 131 int32 go_read(int32, void *, int32)
 132   __asm__ (GOSYM_PREFIX "runtime.read");
 133
 134 int32
 135 go_read(int32 fd, void *p, int32 n)
 136 {
 137   ssize_t r = runtime_read(fd, p, n);
 138   if (r < 0)
 139     r = - errno;
 140   return (int32)r;
 141 }
 142
 143 int32 go_write1(uintptr, void *, int32)
 144   __asm__ (GOSYM_PREFIX "runtime.write1");
 145
 146 int32
 147 go_write1(uintptr fd, void *p, int32 n)
 148 {
 149   ssize_t r = runtime_write(fd, p, n);
 150   if (r < 0)
 151     r = - errno;
 152   return (int32)r;
 153 }
 154
 155 int32 go_closefd(int32)
 156   __asm__ (GOSYM_PREFIX "runtime.closefd");
 157
 158 int32
 159 go_closefd(int32 fd)
 160 {
 161   return runtime_close(fd);
 162 }
 163
 164 intgo go_errno(void)
 165   __asm__ (GOSYM_PREFIX "runtime.errno");
 166
 167 intgo
 168 go_errno()
 169 {
 170   return (intgo)errno;
 171 }
 172
 173 uintptr getEnd(void)
 174   __asm__ (GOSYM_PREFIX "runtime.getEnd");
 175
 176 uintptr
 177 getEnd()
 178 {
 179 #ifdef _AIX
 180   // mmap adresses range start at 0x30000000 on AIX for 32 bits processes
 181   uintptr end = 0x30000000U;
 182 #else
 183   uintptr end = 0;
 184   uintptr *pend;
 185
 186   pend = &__go_end;
 187   if (pend != nil) {
 188     end = *pend;
 189   }
 190 #endif
 191
 192   return end;
 193 }
 194
 195 // Return an address that is before the read-only data section.
 196 // Unfortunately there is no standard symbol for this so we use a text
 197 // address.
 198
 199 uintptr getText(void)
 200   __asm__ (GOSYM_PREFIX "runtime.getText");
 201
 202 uintptr
 203 getText(void)
 204 {
 205   return (uintptr)(const void *)(getText);
 206 }
 207
 208 // Return the end of the text segment, assumed to come after the
 209 // read-only data section.
 210
 211 uintptr getEtext(void)
 212   __asm__ (GOSYM_PREFIX "runtime.getEtext");
 213
 214 uintptr
 215 getEtext(void)
 216 {
 217   const void *p;
 218
 219   p = __data_start;
 220   if (p == nil)
 221     p = __etext;
 222   if (p == nil)
 223     p = _etext;
 224   return (uintptr)(p);
 225 }
 226
 227 // CPU-specific initialization.
 228 // Fetch CPUID info on x86.
 229
 230 void
 231 runtime_cpuinit()
 232 {
 233 #if defined(__i386__) || defined(__x86_64__)
 234         unsigned int eax, ebx, ecx, edx;
 235
 236         if (__get_cpuid(0, &eax, &ebx, &ecx, &edx)) {
 237                 if (eax != 0
 238                     && ebx == 0x756E6547    // "Genu"
 239                     && edx == 0x49656E69    // "ineI"
 240                     && ecx == 0x6C65746E) { // "ntel"
 241                         lfenceBeforeRdtsc = true;
 242                 }
 243         }
 244         if (__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
 245 #if defined(__i386__)
 246                 if ((edx & bit_SSE2) != 0) {
 247                         hasSSE2 = true;
 248                 }
 249 #endif
 250         }
 251
 252 #if defined(HAVE_AS_X86_AES)
 253         setSupportAES(true);
 254 #endif
 255 #endif
 256 }
 257
 258 // A publication barrier: a store/store barrier.
 259
 260 void publicationBarrier(void)
 261   __asm__ (GOSYM_PREFIX "runtime.publicationBarrier");
 262
 263 void
 264 publicationBarrier()
 265 {
 266   __atomic_thread_fence(__ATOMIC_RELEASE);
 267 }
 268
 269 #ifdef __linux__
 270
 271 /* Currently sbrk0 is only called on GNU/Linux.  */
 272
 273 uintptr sbrk0(void)
 274   __asm__ (GOSYM_PREFIX "runtime.sbrk0");
 275
 276 uintptr
 277 sbrk0()
 278 {
 279   return syscall(SYS_brk, (uintptr)(0));
 280 }
 281
 282 #endif /* __linux__ */