diff options
Diffstat (limited to 'src/runtime/sys_x86.go')
-rw-r--r-- | src/runtime/sys_x86.go | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/runtime/sys_x86.go b/src/runtime/sys_x86.go new file mode 100644 index 000000000..086af8ff1 --- /dev/null +++ b/src/runtime/sys_x86.go @@ -0,0 +1,54 @@ +// Copyright 2013 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. + +// +build amd64 amd64p32 386 + +package runtime + +import "unsafe" + +// adjust Gobuf as it if executed a call to fn with context ctxt +// and then did an immediate gosave. +func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) { + sp := buf.sp + if regSize > ptrSize { + sp -= ptrSize + *(*uintptr)(unsafe.Pointer(sp)) = 0 + } + sp -= ptrSize + *(*uintptr)(unsafe.Pointer(sp)) = buf.pc + buf.sp = sp + 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) { + pc := (*[8]byte)(unsafe.Pointer(buf.pc)) + if pc[0] == 0xe9 { // jmp 4-byte offset + buf.pc = buf.pc + 5 + uintptr(int64(*(*int32)(unsafe.Pointer(&pc[1])))) + return + } + if pc[0] == 0xeb { // jmp 1-byte offset + buf.pc = buf.pc + 2 + uintptr(int64(*(*int8)(unsafe.Pointer(&pc[1])))) + return + } + if pc[0] == 0xcc { + // This is a breakpoint inserted by gdb. We could use + // runtime·findfunc to find the function. But if we + // do that, then we will continue execution at the + // function entry point, and we will not hit the gdb + // breakpoint. So for this case we don't change + // buf.pc, so that when we return we will execute + // the jump instruction and carry on. This means that + // stack unwinding may not work entirely correctly + // (http://golang.org/issue/5723) but the user is + // running under gdb anyhow. + return + } + print("runtime: pc=", pc, " ", hex(pc[0]), " ", hex(pc[1]), " ", hex(pc[2]), " ", hex(pc[3]), " ", hex(pc[4]), "\n") + gothrow("runtime: misuse of rewindmorestack") +} |