diff options
Diffstat (limited to 'libgo/go/runtime/sys_s390x.go')
-rw-r--r-- | libgo/go/runtime/sys_s390x.go | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/libgo/go/runtime/sys_s390x.go b/libgo/go/runtime/sys_s390x.go new file mode 100644 index 00000000000..2aa81e75c06 --- /dev/null +++ b/libgo/go/runtime/sys_s390x.go @@ -0,0 +1,45 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime + +import "unsafe" + +// adjust Gobuf as if it executed a call to fn with context ctxt +// and then did an immediate Gosave. +func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) { + if buf.lr != 0 { + throw("invalid use of gostartcall") + } + buf.lr = buf.pc + buf.pc = uintptr(fn) + buf.ctxt = ctxt +} + +// Called to rewind context saved during morestack back to beginning of function. +// To help us, the linker emits a jmp back to the beginning right after the +// call to morestack. We just have to decode and apply that jump. +func rewindmorestack(buf *gobuf) { + var inst uint64 + if buf.pc&1 == 0 && buf.pc != 0 { + inst = *(*uint64)(unsafe.Pointer(buf.pc)) + switch inst >> 48 { + case 0xa7f4: // BRC (branch relative on condition) instruction. + inst >>= 32 + inst &= 0xFFFF + offset := int64(int16(inst)) + offset <<= 1 + buf.pc += uintptr(offset) + return + case 0xc0f4: // BRCL (branch relative on condition long) instruction. + inst >>= 16 + inst = inst & 0xFFFFFFFF + inst = (inst << 1) & 0xFFFFFFFF + buf.pc += uintptr(int32(inst)) + return + } + } + print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n") + throw("runtime: misuse of rewindmorestack") +} |