libgo/go/syscall/clone_linux.c

   1 /* clone_linux.c -- consistent wrapper around Linux clone syscall
   2
   3    Copyright 2016 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include <errno.h>
   8 #include <sys/syscall.h>
   9
  10 #include "runtime.h"
  11
  12 long rawClone (unsigned long flags, void *child_stack, void *ptid,
  13                void *ctid, void *regs)
  14   __asm__ (GOSYM_PREFIX "syscall.rawClone")
  15   __attribute__ ((no_split_stack));
  16
  17 long
  18 rawClone (unsigned long flags, void *child_stack, void *ptid, void *ctid, void *regs)
  19 {
  20 #if defined(__arc__) || defined(__aarch64__) || defined(__arm__) || defined(__mips__) || defined(__hppa__) || defined(__powerpc__) || defined(__score__) || defined(__i386__) || defined(__xtensa__)
  21   // CLONE_BACKWARDS
  22   return syscall(__NR_clone, flags, child_stack, ptid, regs, ctid);
  23 #elif defined(__s390__) || defined(__cris__)
  24   // CLONE_BACKWARDS2
  25   return syscall(__NR_clone, child_stack, flags, ptid, ctid, regs);
  26 #elif defined(__microblaze__)
  27   // CLONE_BACKWARDS3
  28   return syscall(__NR_clone, flags, child_stack, 0, ptid, ctid, regs);
  29 #elif defined(__sparc__)
  30
  31   /* SPARC has a unique return value convention:
  32
  33      Parent -->  %o0 == child's  pid, %o1 == 0
  34      Child  -->  %o0 == parent's pid, %o1 == 1
  35
  36      Translate this to look like a normal clone.  */
  37
  38 # if defined(__arch64__)
  39
  40 #  define SYSCALL_STRING                                                \
  41         "ta     0x6d;"                                                  \
  42         "bcc,pt %%xcc, 1f;"                                             \
  43         " mov   0, %%g1;"                                               \
  44         "sub    %%g0, %%o0, %%o0;"                                      \
  45         "mov    1, %%g1;"                                               \
  46         "1:"
  47
  48 #  define SYSCALL_CLOBBERS                                              \
  49         "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",                 \
  50         "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",           \
  51         "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",         \
  52         "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",         \
  53         "f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46",         \
  54         "f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62",         \
  55         "cc", "memory"
  56
  57 # else /* __arch64__ */
  58
  59 #  define SYSCALL_STRING                                                \
  60         "ta     0x10;"                                                  \
  61         "bcc    1f;"                                                    \
  62         " mov   0, %%g1;"                                               \
  63         "sub    %%g0, %%o0, %%o0;"                                      \
  64         "mov    1, %%g1;"                                               \
  65         "1:"
  66
  67 #  define SYSCALL_CLOBBERS                                              \
  68         "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",                 \
  69         "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",           \
  70         "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",         \
  71         "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",         \
  72         "cc", "memory"
  73
  74 # endif /* __arch64__ */
  75
  76   register long o0 __asm__ ("o0") = (long)flags;
  77   register long o1 __asm__ ("o1") = (long)child_stack;
  78   register long o2 __asm__ ("o2") = (long)ptid;
  79   register long o3 __asm__ ("o3") = (long)ctid;
  80   register long o4 __asm__ ("o4") = (long)regs;
  81   register long g1 __asm__ ("g1") = __NR_clone;
  82
  83   __asm __volatile (SYSCALL_STRING :
  84                     "=r" (g1), "=r" (o0), "=r" (o1) :
  85                     "0" (g1), "1" (o0), "2" (o1),
  86                     "r" (o2), "r" (o3), "r" (o4) :
  87                     SYSCALL_CLOBBERS);
  88
  89   if (__builtin_expect(g1 != 0, 0))
  90     {
  91       errno = -o0;
  92       o0 = -1L;
  93     }
  94   else
  95     o0 &= (o1 - 1);
  96
  97   return o0;
  98
  99 #else
 100   return syscall(__NR_clone, flags, child_stack, ptid, ctid, regs);
 101 #endif
 102 }