mirror of https://go.googlesource.com/go
136 lines
3.5 KiB
Go
136 lines
3.5 KiB
Go
// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build arm64 && linux
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package runtime
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import (
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"internal/abi"
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"internal/goarch"
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"unsafe"
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)
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type sigContext struct {
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savedRegs sigcontext
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}
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func sigctxtSetContextRegister(ctxt *sigctxt, x uint64) {
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ctxt.regs().regs[26] = x
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}
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func sigctxtAtTrapInstruction(ctxt *sigctxt) bool {
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return *(*uint32)(unsafe.Pointer(ctxt.sigpc())) == 0xd4200000 // BRK 0
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}
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func sigctxtStatus(ctxt *sigctxt) uint64 {
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return ctxt.r20()
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}
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func (h *debugCallHandler) saveSigContext(ctxt *sigctxt) {
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sp := ctxt.sp()
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sp -= 2 * goarch.PtrSize
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ctxt.set_sp(sp)
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*(*uint64)(unsafe.Pointer(uintptr(sp))) = ctxt.lr() // save the current lr
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ctxt.set_lr(ctxt.pc()) // set new lr to the current pc
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// Write the argument frame size.
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*(*uintptr)(unsafe.Pointer(uintptr(sp - 16))) = h.argSize
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// Save current registers.
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h.sigCtxt.savedRegs = *ctxt.regs()
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}
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// case 0
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func (h *debugCallHandler) debugCallRun(ctxt *sigctxt) {
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sp := ctxt.sp()
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memmove(unsafe.Pointer(uintptr(sp)+8), h.argp, h.argSize)
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if h.regArgs != nil {
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storeRegArgs(ctxt.regs(), h.regArgs)
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}
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// Push return PC, which should be the signal PC+4, because
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// the signal PC is the PC of the trap instruction itself.
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ctxt.set_lr(ctxt.pc() + 4)
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// Set PC to call and context register.
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ctxt.set_pc(uint64(h.fv.fn))
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sigctxtSetContextRegister(ctxt, uint64(uintptr(unsafe.Pointer(h.fv))))
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}
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// case 1
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func (h *debugCallHandler) debugCallReturn(ctxt *sigctxt) {
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sp := ctxt.sp()
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memmove(h.argp, unsafe.Pointer(uintptr(sp)+8), h.argSize)
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if h.regArgs != nil {
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loadRegArgs(h.regArgs, ctxt.regs())
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}
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// Restore the old lr from *sp
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olr := *(*uint64)(unsafe.Pointer(uintptr(sp)))
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ctxt.set_lr(olr)
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pc := ctxt.pc()
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ctxt.set_pc(pc + 4) // step to next instruction
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}
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// case 2
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func (h *debugCallHandler) debugCallPanicOut(ctxt *sigctxt) {
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sp := ctxt.sp()
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memmove(unsafe.Pointer(&h.panic), unsafe.Pointer(uintptr(sp)+8), 2*goarch.PtrSize)
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ctxt.set_pc(ctxt.pc() + 4)
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}
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// case 8
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func (h *debugCallHandler) debugCallUnsafe(ctxt *sigctxt) {
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sp := ctxt.sp()
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reason := *(*string)(unsafe.Pointer(uintptr(sp) + 8))
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h.err = plainError(reason)
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ctxt.set_pc(ctxt.pc() + 4)
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}
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// case 16
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func (h *debugCallHandler) restoreSigContext(ctxt *sigctxt) {
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// Restore all registers except for pc and sp
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pc, sp := ctxt.pc(), ctxt.sp()
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*ctxt.regs() = h.sigCtxt.savedRegs
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ctxt.set_pc(pc + 4)
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ctxt.set_sp(sp)
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}
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// storeRegArgs sets up argument registers in the signal
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// context state from an abi.RegArgs.
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//
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// Both src and dst must be non-nil.
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func storeRegArgs(dst *sigcontext, src *abi.RegArgs) {
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for i, r := range src.Ints {
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dst.regs[i] = uint64(r)
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}
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for i, r := range src.Floats {
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*(fpRegAddr(dst, i)) = r
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}
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}
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func loadRegArgs(dst *abi.RegArgs, src *sigcontext) {
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for i := range dst.Ints {
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dst.Ints[i] = uintptr(src.regs[i])
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}
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for i := range dst.Floats {
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dst.Floats[i] = *(fpRegAddr(src, i))
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}
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}
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// fpRegAddr returns the address of the ith fp-simd register in sigcontext.
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func fpRegAddr(dst *sigcontext, i int) *uint64 {
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/* FP-SIMD registers are saved in sigcontext.__reserved, which is orgnized in
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the following C structs:
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struct fpsimd_context {
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struct _aarch64_ctx head;
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__u32 fpsr;
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__u32 fpcr;
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__uint128_t vregs[32];
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};
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struct _aarch64_ctx {
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__u32 magic;
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__u32 size;
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};
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So the offset of the ith FP_SIMD register is 16+i*128.
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*/
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return (*uint64)(unsafe.Pointer(&dst.__reserved[16+i*128]))
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}
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