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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 arm64 && linux
package runtime
import (
"internal/abi"
"internal/goarch"
"unsafe"
)
type sigContext struct {
savedRegs sigcontext
}
func sigctxtSetContextRegister(ctxt *sigctxt, x uint64) {
ctxt.regs().regs[26] = x
}
func sigctxtAtTrapInstruction(ctxt *sigctxt) bool {
return *(*uint32)(unsafe.Pointer(ctxt.sigpc())) == 0xd4200000 // BRK 0
}
func sigctxtStatus(ctxt *sigctxt) uint64 {
return ctxt.r20()
}
func (h *debugCallHandler) saveSigContext(ctxt *sigctxt) {
sp := ctxt.sp()
sp -= 2 * goarch.PtrSize
ctxt.set_sp(sp)
*(*uint64)(unsafe.Pointer(uintptr(sp))) = ctxt.lr() // save the current lr
ctxt.set_lr(ctxt.pc()) // set new lr to the current pc
// Write the argument frame size.
*(*uintptr)(unsafe.Pointer(uintptr(sp - 16))) = h.argSize
// Save current registers.
h.sigCtxt.savedRegs = *ctxt.regs()
}
// case 0
func (h *debugCallHandler) debugCallRun(ctxt *sigctxt) {
sp := ctxt.sp()
memmove(unsafe.Pointer(uintptr(sp)+8), h.argp, h.argSize)
if h.regArgs != nil {
storeRegArgs(ctxt.regs(), h.regArgs)
}
// Push return PC, which should be the signal PC+4, because
// the signal PC is the PC of the trap instruction itself.
ctxt.set_lr(ctxt.pc() + 4)
// Set PC to call and context register.
ctxt.set_pc(uint64(h.fv.fn))
sigctxtSetContextRegister(ctxt, uint64(uintptr(unsafe.Pointer(h.fv))))
}
// case 1
func (h *debugCallHandler) debugCallReturn(ctxt *sigctxt) {
sp := ctxt.sp()
memmove(h.argp, unsafe.Pointer(uintptr(sp)+8), h.argSize)
if h.regArgs != nil {
loadRegArgs(h.regArgs, ctxt.regs())
}
// Restore the old lr from *sp
olr := *(*uint64)(unsafe.Pointer(uintptr(sp)))
ctxt.set_lr(olr)
pc := ctxt.pc()
ctxt.set_pc(pc + 4) // step to next instruction
}
// case 2
func (h *debugCallHandler) debugCallPanicOut(ctxt *sigctxt) {
sp := ctxt.sp()
memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)+8), 2*goarch.PtrSize)
ctxt.set_pc(ctxt.pc() + 4)
}
// case 8
func (h *debugCallHandler) debugCallUnsafe(ctxt *sigctxt) {
sp := ctxt.sp()
reason := *(*string)(unsafe.Pointer(uintptr(sp) + 8))
h.err = plainError(reason)
ctxt.set_pc(ctxt.pc() + 4)
}
// case 16
func (h *debugCallHandler) restoreSigContext(ctxt *sigctxt) {
// Restore all registers except for pc and sp
pc, sp := ctxt.pc(), ctxt.sp()
*ctxt.regs() = h.sigCtxt.savedRegs
ctxt.set_pc(pc + 4)
ctxt.set_sp(sp)
}
// 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) {
for i, r := range src.Ints {
dst.regs[i] = uint64(r)
}
for i, r := range src.Floats {
*(fpRegAddr(dst, i)) = r
}
}
func loadRegArgs(dst *abi.RegArgs, src *sigcontext) {
for i := range dst.Ints {
dst.Ints[i] = uintptr(src.regs[i])
}
for i := range dst.Floats {
dst.Floats[i] = *(fpRegAddr(src, i))
}
}
// fpRegAddr returns the address of the ith fp-simd register in sigcontext.
func fpRegAddr(dst *sigcontext, i int) *uint64 {
/* FP-SIMD registers are saved in sigcontext.__reserved, which is orgnized in
the following C structs:
struct fpsimd_context {
struct _aarch64_ctx head;
__u32 fpsr;
__u32 fpcr;
__uint128_t vregs[32];
};
struct _aarch64_ctx {
__u32 magic;
__u32 size;
};
So the offset of the ith FP_SIMD register is 16+i*128.
*/
return (*uint64)(unsafe.Pointer(&dst.__reserved[16+i*128]))
}
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