libgo/go/runtime/sys_mips64x.go

   1 // Copyright 2015 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 // +build mips64 mips64le
   6
   7 package runtime
   8
   9 import "unsafe"
  10
  11 // adjust Gobuf as if it executed a call to fn with context ctxt
  12 // and then did an immediate Gosave.
  13 func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
  14         if buf.lr != 0 {
  15                 throw("invalid use of gostartcall")
  16         }
  17         buf.lr = buf.pc
  18         buf.pc = uintptr(fn)
  19         buf.ctxt = ctxt
  20 }
  21
  22 // Called to rewind context saved during morestack back to beginning of function.
  23 // To help us, the linker emits a jmp back to the beginning right after the
  24 // call to morestack. We just have to decode and apply that jump.
  25 func rewindmorestack(buf *gobuf) {
  26         var inst uint32
  27         if buf.pc&3 == 0 && buf.pc != 0 {
  28                 inst = *(*uint32)(unsafe.Pointer(buf.pc))
  29                 if inst>>26 == 2 { // JMP addr
  30                         //print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc &^ uintptr(1<<28-1) | uintptr((inst&^0xfc000000)<<2)), "\n");
  31                         buf.pc &^= 1<<28 - 1
  32                         buf.pc |= uintptr((inst &^ 0xfc000000) << 2)
  33                         return
  34                 }
  35                 if inst>>16 == 0x1000 { // BEQ  R0, R0, offset
  36                         //print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc + uintptr(int32(int16(inst&0xffff))<<2 + 4)), "\n");
  37                         buf.pc += uintptr(int32(int16(inst&0xffff))<<2 + 4)
  38                         return
  39                 }
  40         }
  41         print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n")
  42         throw("runtime: misuse of rewindmorestack")
  43 }