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// 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
}
}
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