1 files changed, 132 insertions, 0 deletions
diff --git a/src/runtime/export_debug_amd64_test.go b/src/runtime/export_debug_amd64_test.go
new file mode 100644
index 0000000000..f9908cd494
--- /dev/null
+++ b/src/runtime/export_debug_amd64_test.go
@@ -0,0 +1,132 @@
+// Copyright 2022 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.
+
+//go:build amd64 && linux
+
+package runtime
+
+import (
+	"internal/abi"
+	"internal/goarch"
+	"unsafe"
+)
+
+type sigContext struct {
+	savedRegs sigcontext
+	// sigcontext.fpstate is a pointer, so we need to save
+	// the its value with a fpstate1 structure.
+	savedFP fpstate1
+}
+
+func sigctxtSetContextRegister(ctxt *sigctxt, x uint64) {
+	ctxt.regs().rdx = x
+}
+
+func sigctxtAtTrapInstruction(ctxt *sigctxt) bool {
+	return *(*byte)(unsafe.Pointer(uintptr(ctxt.rip() - 1))) == 0xcc // INT 3
+}
+
+func sigctxtStatus(ctxt *sigctxt) uint64 {
+	return ctxt.r12()
+}
+
+func (h *debugCallHandler) saveSigContext(ctxt *sigctxt) {
+	// Push current PC on the stack.
+	rsp := ctxt.rsp() - goarch.PtrSize
+	*(*uint64)(unsafe.Pointer(uintptr(rsp))) = ctxt.rip()
+	ctxt.set_rsp(rsp)
+	// Write the argument frame size.
+	*(*uintptr)(unsafe.Pointer(uintptr(rsp - 16))) = h.argSize
+	// Save current registers.
+	h.sigCtxt.savedRegs = *ctxt.regs()
+	h.sigCtxt.savedFP = *h.sigCtxt.savedRegs.fpstate
+	h.sigCtxt.savedRegs.fpstate = nil
+}
+
+// case 0
+func (h *debugCallHandler) debugCallRun(ctxt *sigctxt) {
+	rsp := ctxt.rsp()
+	memmove(unsafe.Pointer(uintptr(rsp)), h.argp, h.argSize)
+	if h.regArgs != nil {
+		storeRegArgs(ctxt.regs(), h.regArgs)
+	}
+	// Push return PC.
+	rsp -= goarch.PtrSize
+	ctxt.set_rsp(rsp)
+	// The signal PC is the next PC of the trap instruction.
+	*(*uint64)(unsafe.Pointer(uintptr(rsp))) = ctxt.rip()
+	// Set PC to call and context register.
+	ctxt.set_rip(uint64(h.fv.fn))
+	sigctxtSetContextRegister(ctxt, uint64(uintptr(unsafe.Pointer(h.fv))))
+}
+
+// case 1
+func (h *debugCallHandler) debugCallReturn(ctxt *sigctxt) {
+	rsp := ctxt.rsp()
+	memmove(h.argp, unsafe.Pointer(uintptr(rsp)), h.argSize)
+	if h.regArgs != nil {
+		loadRegArgs(h.regArgs, ctxt.regs())
+	}
+}
+
+// case 2
+func (h *debugCallHandler) debugCallPanicOut(ctxt *sigctxt) {
+	rsp := ctxt.rsp()
+	memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(rsp)), 2*goarch.PtrSize)
+}
+
+// case 8
+func (h *debugCallHandler) debugCallUnsafe(ctxt *sigctxt) {
+	rsp := ctxt.rsp()
+	reason := *(*string)(unsafe.Pointer(uintptr(rsp)))
+	h.err = plainError(reason)
+}
+
+// case 16
+func (h *debugCallHandler) restoreSigContext(ctxt *sigctxt) {
+	// Restore all registers except RIP and RSP.
+	rip, rsp := ctxt.rip(), ctxt.rsp()
+	fp := ctxt.regs().fpstate
+	*ctxt.regs() = h.sigCtxt.savedRegs
+	ctxt.regs().fpstate = fp
+	*fp = h.sigCtxt.savedFP
+	ctxt.set_rip(rip)
+	ctxt.set_rsp(rsp)
+}
+
+// storeRegArgs sets up argument registers in the signal
+// context state from an abi.RegArgs.
+//
+// Both src and dst must be non-nil.
+func storeRegArgs(dst *sigcontext, src *abi.RegArgs) {
+	dst.rax = uint64(src.Ints[0])
+	dst.rbx = uint64(src.Ints[1])
+	dst.rcx = uint64(src.Ints[2])
+	dst.rdi = uint64(src.Ints[3])
+	dst.rsi = uint64(src.Ints[4])
+	dst.r8 = uint64(src.Ints[5])
+	dst.r9 = uint64(src.Ints[6])
+	dst.r10 = uint64(src.Ints[7])
+	dst.r11 = uint64(src.Ints[8])
+	for i := range src.Floats {
+		dst.fpstate._xmm[i].element[0] = uint32(src.Floats[i] >> 0)
+		dst.fpstate._xmm[i].element[1] = uint32(src.Floats[i] >> 32)
+	}
+}
+
+func loadRegArgs(dst *abi.RegArgs, src *sigcontext) {
+	dst.Ints[0] = uintptr(src.rax)
+	dst.Ints[1] = uintptr(src.rbx)
+	dst.Ints[2] = uintptr(src.rcx)
+	dst.Ints[3] = uintptr(src.rdi)
+	dst.Ints[4] = uintptr(src.rsi)
+	dst.Ints[5] = uintptr(src.r8)
+	dst.Ints[6] = uintptr(src.r9)
+	dst.Ints[7] = uintptr(src.r10)
+	dst.Ints[8] = uintptr(src.r11)
+	for i := range dst.Floats {
+		dst.Floats[i] = uint64(src.fpstate._xmm[i].element[0]) << 0
+		dst.Floats[i] |= uint64(src.fpstate._xmm[i].element[1]) << 32
+	}
+}