Files
delve/pkg/proc/riscv64_arch.go
Alessandro Arzilli 05dc760877 *: mark riscv64 port as experimental (#3835)
Delete non-working prologue detection code and mark port as experimental.

Updates #3832
2024-10-14 11:04:03 -07:00

287 lines
9.9 KiB
Go

package proc
import (
"encoding/binary"
"fmt"
"strings"
"github.com/go-delve/delve/pkg/dwarf/frame"
"github.com/go-delve/delve/pkg/dwarf/op"
"github.com/go-delve/delve/pkg/dwarf/regnum"
)
// ebreak instruction: 0x00100073
var riscv64BreakInstruction = []byte{0x73, 0x00, 0x10, 0x00}
// c.ebreak instruction: 0x9002
var riscv64CompressedBreakInstruction = []byte{0x02, 0x90}
// RISCV64Arch returns an initialized RISCV64 struct.
func RISCV64Arch(goos string) *Arch {
return &Arch{
Name: "riscv64",
ptrSize: 8,
maxInstructionLength: 4,
breakpointInstruction: riscv64CompressedBreakInstruction,
altBreakpointInstruction: riscv64BreakInstruction,
breakInstrMovesPC: false,
derefTLS: false,
prologues: nil,
fixFrameUnwindContext: riscv64FixFrameUnwindContext,
switchStack: riscv64SwitchStack,
regSize: riscv64RegSize,
RegistersToDwarfRegisters: riscv64RegistersToDwarfRegisters,
addrAndStackRegsToDwarfRegisters: riscv64AddrAndStackRegsToDwarfRegisters,
DwarfRegisterToString: riscv64DwarfRegisterToString,
inhibitStepInto: func(*BinaryInfo, uint64) bool { return false },
asmDecode: riscv64AsmDecode,
usesLR: true,
PCRegNum: regnum.RISCV64_PC,
SPRegNum: regnum.RISCV64_SP,
asmRegisters: riscv64AsmRegisters,
RegisterNameToDwarf: nameToDwarfFunc(regnum.RISCV64NameToDwarf),
RegnumToString: regnum.RISCV64ToName,
debugCallMinStackSize: 288, // TODO
maxRegArgBytes: 16*8 + 16*8, // 16 int argument registers plus 16 float argument registers
}
}
func riscv64FixFrameUnwindContext(fctxt *frame.FrameContext, pc uint64, bi *BinaryInfo) *frame.FrameContext {
a := bi.Arch
if a.sigreturnfn == nil {
a.sigreturnfn = bi.lookupOneFunc("runtime.sigreturn")
}
if (fctxt == nil) || ((a.sigreturnfn != nil) && (pc >= a.sigreturnfn.Entry) && (pc < a.sigreturnfn.End)) {
// When there's no frame descriptor entry use BP (the frame pointer) instead
// - return register is [bp + a.PtrSize()] (i.e. [cfa-a.PtrSize()])
// - cfa is bp + a.PtrSize()*2
// - bp is [bp] (i.e. [cfa-a.PtrSize()*2])
// - sp is cfa
// When the signal handler runs it will move the execution to the signal
// handling stack (installed using the sigaltstack system call).
// This isn't a proper stack switch: the pointer to g in TLS will still
// refer to whatever g was executing on that thread before the signal was
// received.
// Since go did not execute a stack switch the previous value of sp, pc
// and bp is not saved inside g.sched, as it normally would.
// The only way to recover is to either read sp/pc from the signal context
// parameter (the ucontext_t* parameter) or to unconditionally follow the
// frame pointer when we get to runtime.sigreturn (which is what we do
// here).
return &frame.FrameContext{
RetAddrReg: regnum.RISCV64_PC,
Regs: map[uint64]frame.DWRule{
regnum.RISCV64_PC: {
Rule: frame.RuleOffset,
Offset: int64(-a.PtrSize()),
},
regnum.RISCV64_FP: {
Rule: frame.RuleOffset,
Offset: int64(-2 * a.PtrSize()),
},
regnum.RISCV64_SP: {
Rule: frame.RuleValOffset,
Offset: 0,
},
},
CFA: frame.DWRule{
Rule: frame.RuleCFA,
Reg: regnum.RISCV64_FP,
Offset: int64(2 * a.PtrSize()),
},
}
}
if a.crosscall2fn == nil {
a.crosscall2fn = bi.lookupOneFunc("crosscall2")
}
if a.crosscall2fn != nil && pc >= a.crosscall2fn.Entry && pc < a.crosscall2fn.End {
rule := fctxt.CFA
if rule.Offset == crosscall2SPOffsetBad {
rule.Offset += crosscall2SPOffset
}
fctxt.CFA = rule
}
// We assume that FP is the frame pointer and we want to keep it updated,
// so that we can use it to unwind the stack even when we encounter frames
// without descriptor entries.
// If there isn't a rule already we emit one.
if fctxt.Regs[regnum.RISCV64_FP].Rule == frame.RuleUndefined {
fctxt.Regs[regnum.RISCV64_FP] = frame.DWRule{
Rule: frame.RuleFramePointer,
Reg: regnum.RISCV64_FP,
Offset: 0,
}
}
if fctxt.Regs[regnum.RISCV64_LR].Rule == frame.RuleUndefined {
fctxt.Regs[regnum.RISCV64_LR] = frame.DWRule{
Rule: frame.RuleRegister,
Reg: regnum.RISCV64_LR,
Offset: 0,
}
}
return fctxt
}
const riscv64cgocallSPOffsetSaveSlot = 0x8
const riscv64prevG0schedSPOffsetSaveSlot = 0x10
func riscv64SwitchStack(it *stackIterator, callFrameRegs *op.DwarfRegisters) bool {
if it.frame.Current.Fn == nil {
if it.systemstack && it.g != nil && it.top {
it.switchToGoroutineStack()
return true
}
return false
}
switch it.frame.Current.Fn.Name {
case "runtime.cgocallback_gofunc", "runtime.cgocallback", "runtime.asmcgocall", "crosscall2":
// cgostacktrace is broken on riscv64, so do nothing here.
case "runtime.goexit", "runtime.rt0_go", "runtime.mcall":
// Look for "top of stack" functions.
it.atend = true
return true
case "runtime.mstart":
// Calls to runtime.systemstack will switch to the systemstack then:
// 1. alter the goroutine stack so that it looks like systemstack_switch
// was called
// 2. alter the system stack so that it looks like the bottom-most frame
// belongs to runtime.mstart
// If we find a runtime.mstart frame on the system stack of a goroutine
// parked on runtime.systemstack_switch we assume runtime.systemstack was
// called and continue tracing from the parked position.
if it.top || !it.systemstack || it.g == nil {
return false
}
if fn := it.bi.PCToFunc(it.g.PC); fn == nil || fn.Name != "runtime.systemstack_switch" {
return false
}
it.switchToGoroutineStack()
return true
default:
if it.systemstack && it.top && it.g != nil && strings.HasPrefix(it.frame.Current.Fn.Name, "runtime.") && it.frame.Current.Fn.Name != "runtime.throw" && it.frame.Current.Fn.Name != "runtime.fatalthrow" {
// The runtime switches to the system stack in multiple places.
// This usually happens through a call to runtime.systemstack but there
// are functions that switch to the system stack manually (for example
// runtime.morestack).
// Since we are only interested in printing the system stack for cgo
// calls we switch directly to the goroutine stack if we detect that the
// function at the top of the stack is a runtime function.
it.switchToGoroutineStack()
return true
}
}
fn := it.bi.PCToFunc(it.frame.Ret)
if fn == nil {
return false
}
switch fn.Name {
case "runtime.asmcgocall":
if !it.systemstack {
return false
}
// This function is called by a goroutine to execute a C function and
// switches from the goroutine stack to the system stack.
// Since we are unwinding the stack from callee to caller we have to switch
// from the system stack to the goroutine stack.
off, _ := readIntRaw(it.mem, uint64(callFrameRegs.SP()+riscv64cgocallSPOffsetSaveSlot), int64(it.bi.Arch.PtrSize()))
oldsp := callFrameRegs.SP()
newsp := uint64(int64(it.stackhi) - off)
// runtime.asmcgocall can also be called from inside the system stack,
// in that case no stack switch actually happens
if newsp == oldsp {
return false
}
it.systemstack = false
callFrameRegs.Reg(callFrameRegs.SPRegNum).Uint64Val = uint64(int64(newsp))
return false
case "runtime.cgocallback_gofunc":
// For a detailed description of how this works read the long comment at
// the start of $GOROOT/src/runtime/cgocall.go and the source code of
// runtime.cgocallback_gofunc in $GOROOT/src/runtime/asm_riscv64.s
//
// When a C functions calls back into go it will eventually call into
// runtime.cgocallback_gofunc which is the function that does the stack
// switch from the system stack back into the goroutine stack
// Since we are going backwards on the stack here we see the transition
// as goroutine stack -> system stack.
if it.systemstack {
return false
}
it.loadG0SchedSP()
if it.g0_sched_sp <= 0 {
return false
}
// entering the system stack
callFrameRegs.Reg(callFrameRegs.SPRegNum).Uint64Val = it.g0_sched_sp
// reads the previous value of g0.sched.sp that runtime.cgocallback_gofunc saved on the stack
it.g0_sched_sp, _ = readUintRaw(it.mem, uint64(callFrameRegs.SP()+riscv64prevG0schedSPOffsetSaveSlot), int64(it.bi.Arch.PtrSize()))
it.systemstack = true
return false
}
return false
}
func riscv64RegSize(regnum uint64) int {
// All CPU registers are 64bit
return 8
}
func riscv64RegistersToDwarfRegisters(staticBase uint64, regs Registers) *op.DwarfRegisters {
dregs := initDwarfRegistersFromSlice(int(regnum.RISCV64MaxRegNum()), regs, regnum.RISCV64NameToDwarf)
dr := op.NewDwarfRegisters(staticBase, dregs, binary.LittleEndian, regnum.RISCV64_PC, regnum.RISCV64_SP, regnum.RISCV64_FP, regnum.RISCV64_LR)
dr.SetLoadMoreCallback(loadMoreDwarfRegistersFromSliceFunc(dr, regs, regnum.RISCV64NameToDwarf))
return dr
}
func riscv64AddrAndStackRegsToDwarfRegisters(staticBase, pc, sp, bp, lr uint64) op.DwarfRegisters {
dregs := make([]*op.DwarfRegister, int(regnum.RISCV64_PC+1))
dregs[regnum.RISCV64_PC] = op.DwarfRegisterFromUint64(pc)
dregs[regnum.RISCV64_SP] = op.DwarfRegisterFromUint64(sp)
dregs[regnum.RISCV64_FP] = op.DwarfRegisterFromUint64(bp)
dregs[regnum.RISCV64_LR] = op.DwarfRegisterFromUint64(lr)
return *op.NewDwarfRegisters(staticBase, dregs, binary.LittleEndian, regnum.RISCV64_PC, regnum.RISCV64_SP, regnum.RISCV64_FP, regnum.RISCV64_LR)
}
func riscv64DwarfRegisterToString(i int, reg *op.DwarfRegister) (name string, floatingPoint bool, repr string) {
name = regnum.RISCV64ToName(uint64(i))
if reg == nil {
return name, false, ""
}
if strings.HasPrefix(name, "F") {
return name, true, fmt.Sprintf("%#016x", reg.Uint64Val)
} else {
return name, false, fmt.Sprintf("%#016x", reg.Uint64Val)
}
}