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fncall.go
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fncall.go
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package proc
import (
"debug/dwarf"
"encoding/binary"
"errors"
"fmt"
"go/ast"
"go/constant"
"go/token"
"reflect"
"sort"
"strconv"
"strings"
"github.com/go-delve/delve/pkg/dwarf/godwarf"
"github.com/go-delve/delve/pkg/dwarf/op"
"github.com/go-delve/delve/pkg/dwarf/reader"
"github.com/go-delve/delve/pkg/dwarf/regnum"
"github.com/go-delve/delve/pkg/goversion"
"github.com/go-delve/delve/pkg/logflags"
)
// This file implements the function call injection introduced in go1.11.
//
// The protocol is described in $GOROOT/src/runtime/asm_amd64.s in the
// comments for function runtime·debugCallV1.
//
// The main entry point is EvalExpressionWithCalls which will start a goroutine to
// evaluate the provided expression.
// This goroutine can either return immediately, if no function calls were
// needed, or write a continue request to the scope.callCtx.continueRequest
// channel. When this happens EvalExpressionWithCalls will call Continue and
// return.
//
// The Continue loop will write to scope.callCtx.continueCompleted when it
// hits a breakpoint in the call injection protocol.
//
// The work of setting up the function call and executing the protocol is
// done by evalFunctionCall and funcCallStep.
const (
debugCallFunctionNamePrefix1 = "debugCall"
debugCallFunctionNamePrefix2 = "runtime.debugCall"
maxDebugCallVersion = 2
maxArgFrameSize = 65535
)
var (
errFuncCallUnsupported = errors.New("function calls not supported by this version of Go")
errFuncCallUnsupportedBackend = errors.New("backend does not support function calls")
errFuncCallInProgress = errors.New("cannot call function while another function call is already in progress")
errNoGoroutine = errors.New("no goroutine selected")
errGoroutineNotRunning = errors.New("selected goroutine not running")
errNotEnoughStack = errors.New("not enough stack space")
errTooManyArguments = errors.New("too many arguments")
errNotEnoughArguments = errors.New("not enough arguments")
errNotAGoFunction = errors.New("not a Go function")
errFuncCallNotAllowed = errors.New("function calls not allowed without using 'call'")
errFuncCallNotAllowedStrAlloc = errors.New("literal string can not be allocated because function calls are not allowed without using 'call'")
)
type functionCallState struct {
// savedRegs contains the saved registers
savedRegs Registers
// err contains a saved error
err error
// expr is the expression being evaluated
expr *ast.CallExpr
// fn is the function that is being called
fn *Function
// receiver is the receiver argument for the function
receiver *Variable
// closureAddr is the address of the closure being called
closureAddr uint64
// formalArgs are the formal arguments of fn
formalArgs []funcCallArg
// argFrameSize contains the size of the arguments
argFrameSize int64
// retvars contains the return variables after the function call terminates without panic'ing
retvars []*Variable
// panicvar is a variable used to store the value of the panic, if the
// called function panics.
panicvar *Variable
// lateCallFailure is set to true if the function call could not be
// completed after we started evaluating the arguments.
lateCallFailure bool
}
type callContext struct {
p *Target
// checkEscape is true if the escape check should be performed.
// See service/api.DebuggerCommand.UnsafeCall in service/api/types.go.
checkEscape bool
// retLoadCfg is the load configuration used to load return values
retLoadCfg LoadConfig
// Write to continueRequest to request a call to Continue from the
// debugger's main goroutine.
// Read from continueCompleted to wait for the target process to stop at
// one of the interaction point of the function call protocol.
// To signal that evaluation is completed a value will be written to
// continueRequest having cont == false and the return values in ret.
continueRequest chan<- continueRequest
continueCompleted <-chan *G
// injectionThread is the thread to use for nested call injections if the
// original injection goroutine isn't running (because we are in Go 1.15)
injectionThread Thread
// stacks is a slice of known goroutine stacks used to check for
// inappropriate escapes
stacks []stack
}
type continueRequest struct {
cont bool
err error
ret *Variable
}
type callInjection struct {
// if continueCompleted is not nil it means we are in the process of
// executing an injected function call, see comments throughout
// pkg/proc/fncall.go for a description of how this works.
continueCompleted chan<- *G
continueRequest <-chan continueRequest
startThreadID int
endCallInjection func()
}
func (callCtx *callContext) doContinue() *G {
callCtx.continueRequest <- continueRequest{cont: true}
return <-callCtx.continueCompleted
}
func (callCtx *callContext) doReturn(ret *Variable, err error) {
if callCtx == nil {
return
}
callCtx.continueRequest <- continueRequest{cont: false, ret: ret, err: err}
}
// EvalExpressionWithCalls is like EvalExpression but allows function calls in 'expr'.
// Because this can only be done in the current goroutine, unlike
// EvalExpression, EvalExpressionWithCalls is not a method of EvalScope.
func EvalExpressionWithCalls(grp *TargetGroup, g *G, expr string, retLoadCfg LoadConfig, checkEscape bool) error {
t := grp.Selected
bi := t.BinInfo()
if !t.SupportsFunctionCalls() {
return errFuncCallUnsupportedBackend
}
// check that the target goroutine is running
if g == nil {
return errNoGoroutine
}
if g.Status != Grunning || g.Thread == nil {
return errGoroutineNotRunning
}
if callinj := t.fncallForG[g.ID]; callinj != nil && callinj.continueCompleted != nil {
return errFuncCallInProgress
}
dbgcallfn, _ := debugCallFunction(bi)
if dbgcallfn == nil {
return errFuncCallUnsupported
}
scope, err := GoroutineScope(t, g.Thread)
if err != nil {
return err
}
continueRequest := make(chan continueRequest)
continueCompleted := make(chan *G)
scope.callCtx = &callContext{
p: t,
checkEscape: checkEscape,
retLoadCfg: retLoadCfg,
continueRequest: continueRequest,
continueCompleted: continueCompleted,
}
endCallInjection, err := t.proc.StartCallInjection()
if err != nil {
return err
}
t.fncallForG[g.ID] = &callInjection{
continueCompleted: continueCompleted,
continueRequest: continueRequest,
startThreadID: 0,
endCallInjection: endCallInjection,
}
go scope.EvalExpression(expr, retLoadCfg)
contReq, ok := <-continueRequest
if contReq.cont {
return grp.Continue()
}
return finishEvalExpressionWithCalls(t, g, contReq, ok)
}
func finishEvalExpressionWithCalls(t *Target, g *G, contReq continueRequest, ok bool) error {
fncallLog("stashing return values for %d in thread=%d", g.ID, g.Thread.ThreadID())
g.Thread.Common().CallReturn = true
var err error
if !ok {
err = errors.New("internal error EvalExpressionWithCalls didn't return anything")
} else if contReq.err != nil {
if fpe, ispanic := contReq.err.(fncallPanicErr); ispanic {
g.Thread.Common().returnValues = []*Variable{fpe.panicVar}
} else {
err = contReq.err
}
} else if contReq.ret == nil {
g.Thread.Common().returnValues = nil
} else if contReq.ret.Addr == 0 && contReq.ret.DwarfType == nil && contReq.ret.Kind == reflect.Invalid {
// this is a variable returned by a function call with multiple return values
r := make([]*Variable, len(contReq.ret.Children))
for i := range contReq.ret.Children {
r[i] = &contReq.ret.Children[i]
}
g.Thread.Common().returnValues = r
} else {
g.Thread.Common().returnValues = []*Variable{contReq.ret}
}
close(t.fncallForG[g.ID].continueCompleted)
callinj := t.fncallForG[g.ID]
for goid := range t.fncallForG {
if t.fncallForG[goid] == callinj {
delete(t.fncallForG, goid)
}
}
callinj.endCallInjection()
return err
}
// evalFunctionCall evaluates a function call.
// If this is a built-in function it's evaluated directly.
// Otherwise this will start the function call injection protocol and
// request that the target process resumes.
// See the comment describing the field EvalScope.callCtx for a description
// of the preconditions that make starting the function call protocol
// possible.
// See runtime.debugCallV1 in $GOROOT/src/runtime/asm_amd64.s for a
// description of the protocol.
func evalFunctionCall(scope *EvalScope, node *ast.CallExpr) (*Variable, error) {
r, err := scope.evalBuiltinCall(node)
if r != nil || err != nil {
// it was a builtin call
return r, err
}
if scope.callCtx == nil {
return nil, errFuncCallNotAllowed
}
thread := scope.g.Thread
stacklo := scope.g.stack.lo
if thread == nil {
// We are doing a nested function call and using Go 1.15, the original
// injection goroutine was suspended and now we are using a different
// goroutine, evaluation still happened on the original goroutine but we
// need to use a different thread to do the nested call injection.
thread = scope.callCtx.injectionThread
g2, err := GetG(thread)
if err != nil {
return nil, err
}
stacklo = g2.stack.lo
}
if thread == nil {
return nil, errGoroutineNotRunning
}
p := scope.callCtx.p
bi := scope.BinInfo
if !p.SupportsFunctionCalls() {
return nil, errFuncCallUnsupportedBackend
}
dbgcallfn, dbgcallversion := debugCallFunction(bi)
if dbgcallfn == nil {
return nil, errFuncCallUnsupported
}
// check that there are at least 256 bytes free on the stack
regs, err := thread.Registers()
if err != nil {
return nil, err
}
regs, err = regs.Copy()
if err != nil {
return nil, err
}
if regs.SP()-bi.Arch.debugCallMinStackSize <= stacklo {
return nil, errNotEnoughStack
}
protocolReg, ok := debugCallProtocolReg(bi.Arch.Name, dbgcallversion)
if !ok {
return nil, errFuncCallUnsupported
}
if bi.Arch.RegistersToDwarfRegisters(0, regs).Reg(protocolReg) == nil {
return nil, errFuncCallUnsupportedBackend
}
fncall := functionCallState{
expr: node,
savedRegs: regs,
}
err = funcCallEvalFuncExpr(scope, &fncall, false)
if err != nil {
return nil, err
}
switch bi.Arch.Name {
case "amd64":
if err := callOP(bi, thread, regs, dbgcallfn.Entry); err != nil {
return nil, err
}
// write the desired argument frame size at SP-(2*pointer_size) (the extra pointer is the saved PC)
if err := writePointer(bi, scope.Mem, regs.SP()-3*uint64(bi.Arch.PtrSize()), uint64(fncall.argFrameSize)); err != nil {
return nil, err
}
case "arm64":
// debugCallV2 on arm64 needs a special call sequence, callOP can not be used
sp := regs.SP()
sp -= 2 * uint64(bi.Arch.PtrSize())
if err := setSP(thread, sp); err != nil {
return nil, err
}
if err := writePointer(bi, scope.Mem, sp, regs.LR()); err != nil {
return nil, err
}
if err := setLR(thread, regs.PC()); err != nil {
return nil, err
}
if err := writePointer(bi, scope.Mem, sp-uint64(2*bi.Arch.PtrSize()), uint64(fncall.argFrameSize)); err != nil {
return nil, err
}
regs, err = thread.Registers()
if err != nil {
return nil, err
}
regs, err = regs.Copy()
if err != nil {
return nil, err
}
fncall.savedRegs = regs
err = setPC(thread, dbgcallfn.Entry)
if err != nil {
return nil, err
}
}
fncallLog("function call initiated %v frame size %d goroutine %d (thread %d)", fncall.fn, fncall.argFrameSize, scope.g.ID, thread.ThreadID())
thread.Breakpoint().Clear() // since we moved address in PC the thread is no longer stopped at a breakpoint, leaving the breakpoint set will confuse Continue
p.fncallForG[scope.g.ID].startThreadID = thread.ThreadID()
spoff := int64(scope.Regs.Uint64Val(scope.Regs.SPRegNum)) - int64(scope.g.stack.hi)
bpoff := int64(scope.Regs.Uint64Val(scope.Regs.BPRegNum)) - int64(scope.g.stack.hi)
fboff := scope.Regs.FrameBase - int64(scope.g.stack.hi)
for {
scope.callCtx.injectionThread = nil
g := scope.callCtx.doContinue()
// Go 1.15 will move call injection execution to a different goroutine,
// but we want to keep evaluation on the original goroutine.
if g.ID == scope.g.ID {
scope.g = g
} else {
// We are in Go 1.15 and we switched to a new goroutine, the original
// goroutine is now parked and therefore does not have a thread
// associated.
scope.g.Thread = nil
scope.g.Status = Gwaiting
scope.callCtx.injectionThread = g.Thread
}
// adjust the value of registers inside scope
pcreg, bpreg, spreg := scope.Regs.Reg(scope.Regs.PCRegNum), scope.Regs.Reg(scope.Regs.BPRegNum), scope.Regs.Reg(scope.Regs.SPRegNum)
scope.Regs.ClearRegisters()
scope.Regs.AddReg(scope.Regs.PCRegNum, pcreg)
scope.Regs.AddReg(scope.Regs.BPRegNum, bpreg)
scope.Regs.AddReg(scope.Regs.SPRegNum, spreg)
scope.Regs.Reg(scope.Regs.SPRegNum).Uint64Val = uint64(spoff + int64(scope.g.stack.hi))
scope.Regs.Reg(scope.Regs.BPRegNum).Uint64Val = uint64(bpoff + int64(scope.g.stack.hi))
scope.Regs.FrameBase = fboff + int64(scope.g.stack.hi)
scope.Regs.CFA = scope.frameOffset + int64(scope.g.stack.hi)
finished := funcCallStep(scope, &fncall, g.Thread, protocolReg, dbgcallfn.Name)
if finished {
break
}
}
if fncall.err != nil {
return nil, fncall.err
}
if fncall.panicvar != nil {
return nil, fncallPanicErr{fncall.panicvar}
}
switch len(fncall.retvars) {
case 0:
r := newVariable("", 0, nil, scope.BinInfo, nil)
r.loaded = true
r.Unreadable = errors.New("no return values")
return r, nil
case 1:
return fncall.retvars[0], nil
default:
// create a fake variable without address or type to return multiple values
r := newVariable("", 0, nil, scope.BinInfo, nil)
r.loaded = true
r.Children = make([]Variable, len(fncall.retvars))
for i := range fncall.retvars {
r.Children[i] = *fncall.retvars[i]
}
return r, nil
}
}
// fncallPanicErr is the error returned if a called function panics
type fncallPanicErr struct {
panicVar *Variable
}
func (err fncallPanicErr) Error() string {
return "panic calling a function"
}
func fncallLog(fmtstr string, args ...interface{}) {
logflags.FnCallLogger().Infof(fmtstr, args...)
}
// writePointer writes val as an architecture pointer at addr in mem.
func writePointer(bi *BinaryInfo, mem MemoryReadWriter, addr, val uint64) error {
ptrbuf := make([]byte, bi.Arch.PtrSize())
// TODO: use target architecture endianness instead of LittleEndian
switch len(ptrbuf) {
case 4:
binary.LittleEndian.PutUint32(ptrbuf, uint32(val))
case 8:
binary.LittleEndian.PutUint64(ptrbuf, val)
default:
panic(fmt.Errorf("unsupported pointer size %d", len(ptrbuf)))
}
_, err := mem.WriteMemory(addr, ptrbuf)
return err
}
// callOP simulates a call instruction on the given thread:
// * pushes the current value of PC on the stack (adjusting SP)
// * changes the value of PC to callAddr
// Note: regs are NOT updated!
func callOP(bi *BinaryInfo, thread Thread, regs Registers, callAddr uint64) error {
switch bi.Arch.Name {
case "amd64":
sp := regs.SP()
// push PC on the stack
sp -= uint64(bi.Arch.PtrSize())
if err := setSP(thread, sp); err != nil {
return err
}
if err := writePointer(bi, thread.ProcessMemory(), sp, regs.PC()); err != nil {
return err
}
return setPC(thread, callAddr)
case "arm64":
if err := setLR(thread, regs.PC()); err != nil {
return err
}
return setPC(thread, callAddr)
default:
panic("not implemented")
}
}
// funcCallEvalFuncExpr evaluates expr.Fun and returns the function that we're trying to call.
// If allowCalls is false function calls will be disabled even if scope.callCtx != nil
func funcCallEvalFuncExpr(scope *EvalScope, fncall *functionCallState, allowCalls bool) error {
bi := scope.BinInfo
if !allowCalls {
callCtx := scope.callCtx
scope.callCtx = nil
defer func() {
scope.callCtx = callCtx
}()
}
fnvar, err := scope.evalAST(fncall.expr.Fun)
if err == errFuncCallNotAllowed {
// we can't determine the frame size because callexpr.Fun can't be
// evaluated without enabling function calls, just set up an argument
// frame for the maximum possible argument size.
fncall.argFrameSize = maxArgFrameSize
return nil
} else if err != nil {
return err
}
if fnvar.Kind != reflect.Func {
return fmt.Errorf("expression %q is not a function", exprToString(fncall.expr.Fun))
}
fnvar.loadValue(LoadConfig{false, 0, 0, 0, 0, 0})
if fnvar.Unreadable != nil {
return fnvar.Unreadable
}
if fnvar.Base == 0 {
return errors.New("nil pointer dereference")
}
fncall.fn = bi.PCToFunc(uint64(fnvar.Base))
if fncall.fn == nil {
return fmt.Errorf("could not find DIE for function %q", exprToString(fncall.expr.Fun))
}
if !fncall.fn.cu.isgo {
return errNotAGoFunction
}
fncall.closureAddr = fnvar.closureAddr
fncall.argFrameSize, fncall.formalArgs, err = funcCallArgs(fncall.fn, bi, false)
if err != nil {
return err
}
argnum := len(fncall.expr.Args)
// If the function variable has a child then that child is the method
// receiver. However, if the method receiver is not being used (e.g.
// func (_ X) Foo()) then it will not actually be listed as a formal
// argument. Ensure that we are really off by 1 to add the receiver to
// the function call.
if len(fnvar.Children) > 0 && argnum == (len(fncall.formalArgs)-1) {
argnum++
fncall.receiver = &fnvar.Children[0]
fncall.receiver.Name = exprToString(fncall.expr.Fun)
}
if argnum > len(fncall.formalArgs) {
return errTooManyArguments
}
if argnum < len(fncall.formalArgs) {
return errNotEnoughArguments
}
return nil
}
type funcCallArg struct {
name string
typ godwarf.Type
off int64
dwarfEntry *godwarf.Tree // non-nil if Go 1.17+
isret bool
}
// funcCallEvalArgs evaluates the arguments of the function call, copying
// them into the argument frame starting at argFrameAddr.
func funcCallEvalArgs(scope *EvalScope, fncall *functionCallState, formalScope *EvalScope) error {
if scope.g == nil {
// this should never happen
return errNoGoroutine
}
if fncall.receiver != nil {
err := funcCallCopyOneArg(scope, fncall, fncall.receiver, &fncall.formalArgs[0], formalScope)
if err != nil {
return err
}
fncall.formalArgs = fncall.formalArgs[1:]
}
for i := range fncall.formalArgs {
formalArg := &fncall.formalArgs[i]
actualArg, err := scope.evalAST(fncall.expr.Args[i])
if err != nil {
if _, ispanic := err.(fncallPanicErr); ispanic {
return err
}
return fmt.Errorf("error evaluating %q as argument %s in function %s: %v", exprToString(fncall.expr.Args[i]), formalArg.name, fncall.fn.Name, err)
}
actualArg.Name = exprToString(fncall.expr.Args[i])
err = funcCallCopyOneArg(scope, fncall, actualArg, formalArg, formalScope)
if err != nil {
return err
}
}
return nil
}
func funcCallCopyOneArg(scope *EvalScope, fncall *functionCallState, actualArg *Variable, formalArg *funcCallArg, formalScope *EvalScope) error {
if scope.callCtx.checkEscape {
//TODO(aarzilli): only apply the escapeCheck to leaking parameters.
if err := escapeCheck(actualArg, formalArg.name, scope.g.stack); err != nil {
return fmt.Errorf("cannot use %s as argument %s in function %s: %v", actualArg.Name, formalArg.name, fncall.fn.Name, err)
}
for _, stack := range scope.callCtx.stacks {
if err := escapeCheck(actualArg, formalArg.name, stack); err != nil {
return fmt.Errorf("cannot use %s as argument %s in function %s: %v", actualArg.Name, formalArg.name, fncall.fn.Name, err)
}
}
}
//TODO(aarzilli): autmoatic wrapping in interfaces for cases not handled
// by convertToEface.
var formalArgVar *Variable
if formalArg.dwarfEntry != nil {
var err error
formalArgVar, err = extractVarInfoFromEntry(scope.target, formalScope.BinInfo, formalScope.image(), formalScope.Regs, formalScope.Mem, formalArg.dwarfEntry, 0)
if err != nil {
return err
}
} else {
formalArgVar = newVariable(formalArg.name, uint64(formalArg.off+int64(formalScope.Regs.CFA)), formalArg.typ, scope.BinInfo, scope.Mem)
}
if err := scope.setValue(formalArgVar, actualArg, actualArg.Name); err != nil {
return err
}
return nil
}
func funcCallArgs(fn *Function, bi *BinaryInfo, includeRet bool) (argFrameSize int64, formalArgs []funcCallArg, err error) {
dwarfTree, err := fn.cu.image.getDwarfTree(fn.offset)
if err != nil {
return 0, nil, fmt.Errorf("DWARF read error: %v", err)
}
producer := bi.Producer()
trustArgOrder := producer != "" && goversion.ProducerAfterOrEqual(bi.Producer(), 1, 12)
if bi.regabi && fn.cu.optimized && fn.Name != "runtime.mallocgc" {
// Debug info for function arguments on optimized functions is currently
// too incomplete to attempt injecting calls to arbitrary optimized
// functions.
// Prior to regabi we could do this because the ABI was simple enough to
// manually encode it in Delve.
// Runtime.mallocgc is an exception, we specifically patch it's DIE to be
// correct for call injection purposes.
return 0, nil, fmt.Errorf("can not call optimized function %s when regabi is in use", fn.Name)
}
varEntries := reader.Variables(dwarfTree, fn.Entry, int(^uint(0)>>1), reader.VariablesSkipInlinedSubroutines)
// typechecks arguments, calculates argument frame size
for _, entry := range varEntries {
if entry.Tag != dwarf.TagFormalParameter {
continue
}
argname, typ, err := readVarEntry(entry.Tree, fn.cu.image)
if err != nil {
return 0, nil, err
}
typ = resolveTypedef(typ)
var formalArg *funcCallArg
if bi.regabi {
formalArg, err = funcCallArgRegABI(fn, bi, entry, argname, typ, &argFrameSize)
} else {
formalArg, err = funcCallArgOldABI(fn, bi, entry, argname, typ, trustArgOrder, &argFrameSize)
}
if err != nil {
return 0, nil, err
}
if !formalArg.isret || includeRet {
formalArgs = append(formalArgs, *formalArg)
}
}
if bi.regabi {
// The argument frame size is computed conservatively, assuming that
// there's space for each argument on the stack even if its passed in
// registers. Unfortunately this isn't quite enough because the register
// assignment algorithm Go uses can result in an amount of additional
// space used due to alignment requirements, bounded by the number of argument registers.
// Because we currently don't have an easy way to obtain the frame size,
// let's be even more conservative.
// A safe lower-bound on the size of the argument frame includes space for
// each argument plus the total bytes of register arguments.
// This is derived from worst-case alignment padding of up to
// (pointer-word-bytes - 1) per argument passed in registers.
// See: https://github.com/go-delve/delve/pull/2451#discussion_r665761531
// TODO: Make this generic for other platforms.
argFrameSize = alignAddr(argFrameSize, 8)
argFrameSize += int64(bi.Arch.maxRegArgBytes)
}
sort.Slice(formalArgs, func(i, j int) bool {
return formalArgs[i].off < formalArgs[j].off
})
return argFrameSize, formalArgs, nil
}
func funcCallArgOldABI(fn *Function, bi *BinaryInfo, entry reader.Variable, argname string, typ godwarf.Type, trustArgOrder bool, pargFrameSize *int64) (*funcCallArg, error) {
const CFA = 0x1000
var off int64
locprog, _, err := bi.locationExpr(entry, dwarf.AttrLocation, fn.Entry)
if err != nil {
err = fmt.Errorf("could not get argument location of %s: %v", argname, err)
} else {
var pieces []op.Piece
off, pieces, err = op.ExecuteStackProgram(op.DwarfRegisters{CFA: CFA, FrameBase: CFA}, locprog, bi.Arch.PtrSize(), nil)
if err != nil {
err = fmt.Errorf("unsupported location expression for argument %s: %v", argname, err)
}
if pieces != nil {
err = fmt.Errorf("unsupported location expression for argument %s (uses DW_OP_piece)", argname)
}
off -= CFA
}
if err != nil {
if !trustArgOrder {
return nil, err
}
// With Go version 1.12 or later we can trust that the arguments appear
// in the same order as declared, which means we can calculate their
// address automatically.
// With this we can call optimized functions (which sometimes do not have
// an argument address, due to a compiler bug) as well as runtime
// functions (which are always optimized).
off = *pargFrameSize
off = alignAddr(off, typ.Align())
}
if e := off + typ.Size(); e > *pargFrameSize {
*pargFrameSize = e
}
isret, _ := entry.Val(dwarf.AttrVarParam).(bool)
return &funcCallArg{name: argname, typ: typ, off: off, isret: isret}, nil
}
func funcCallArgRegABI(fn *Function, bi *BinaryInfo, entry reader.Variable, argname string, typ godwarf.Type, pargFrameSize *int64) (*funcCallArg, error) {
// Conservatively calculate the full stack argument space for ABI0.
*pargFrameSize = alignAddr(*pargFrameSize, typ.Align())
*pargFrameSize += typ.Size()
isret, _ := entry.Val(dwarf.AttrVarParam).(bool)
return &funcCallArg{name: argname, typ: typ, dwarfEntry: entry.Tree, isret: isret}, nil
}
// alignAddr rounds up addr to a multiple of align. Align must be a power of 2.
func alignAddr(addr, align int64) int64 {
return (addr + int64(align-1)) &^ int64(align-1)
}
func escapeCheck(v *Variable, name string, stack stack) error {
switch v.Kind {
case reflect.Ptr:
var w *Variable
if len(v.Children) == 1 {
// this branch is here to support pointers constructed with typecasts from ints or the '&' operator
w = &v.Children[0]
} else {
w = v.maybeDereference()
}
return escapeCheckPointer(w.Addr, name, stack)
case reflect.Chan, reflect.String, reflect.Slice:
return escapeCheckPointer(v.Base, name, stack)
case reflect.Map:
sv := v.clone()
sv.RealType = resolveTypedef(&(v.RealType.(*godwarf.MapType).TypedefType))
sv = sv.maybeDereference()
return escapeCheckPointer(sv.Addr, name, stack)
case reflect.Struct:
t := v.RealType.(*godwarf.StructType)
for _, field := range t.Field {
fv, _ := v.toField(field)
if err := escapeCheck(fv, fmt.Sprintf("%s.%s", name, field.Name), stack); err != nil {
return err
}
}
case reflect.Array:
for i := int64(0); i < v.Len; i++ {
sv, _ := v.sliceAccess(int(i))
if err := escapeCheck(sv, fmt.Sprintf("%s[%d]", name, i), stack); err != nil {
return err
}
}
case reflect.Func:
if err := escapeCheckPointer(v.funcvalAddr(), name, stack); err != nil {
return err
}
}
return nil
}
func escapeCheckPointer(addr uint64, name string, stack stack) error {
if uint64(addr) >= stack.lo && uint64(addr) < stack.hi {
return fmt.Errorf("stack object passed to escaping pointer: %s", name)
}
return nil
}
const (
debugCallRegPrecheckFailed = 8
debugCallRegCompleteCall = 0
debugCallRegReadReturn = 1
debugCallRegReadPanic = 2
debugCallRegRestoreRegisters = 16
)
// funcCallStep executes one step of the function call injection protocol.
func funcCallStep(callScope *EvalScope, fncall *functionCallState, thread Thread, protocolReg uint64, debugCallName string) bool {
p := callScope.callCtx.p
bi := p.BinInfo()
regs, err := thread.Registers()
if err != nil {
fncall.err = err
return true
}
regval := bi.Arch.RegistersToDwarfRegisters(0, regs).Uint64Val(protocolReg)
if logflags.FnCall() {
loc, _ := thread.Location()
var pc uint64
var fnname string
if loc != nil {
pc = loc.PC
if loc.Fn != nil {
fnname = loc.Fn.Name
}
}
fncallLog("function call interrupt gid=%d (original) thread=%d regval=%#x (PC=%#x in %s)", callScope.g.ID, thread.ThreadID(), regval, pc, fnname)
}
switch regval {
case debugCallRegPrecheckFailed: // 8
archoff := uint64(0)
if bi.Arch.Name == "arm64" {
archoff = 8
}
// get error from top of the stack and return it to user
errvar, err := readStackVariable(p, thread, regs, archoff, "string", loadFullValue)
if err != nil {
fncall.err = fmt.Errorf("could not get precheck error reason: %v", err)
break
}
errvar.Name = "err"
fncall.err = fmt.Errorf("%v", constant.StringVal(errvar.Value))
case debugCallRegCompleteCall: // 0
p.fncallForG[callScope.g.ID].startThreadID = 0
// evaluate arguments of the target function, copy them into its argument frame and call the function
if fncall.fn == nil || fncall.receiver != nil || fncall.closureAddr != 0 {
// if we couldn't figure out which function we are calling before
// (because the function we are calling is the return value of a call to
// another function) now we have to figure it out by recursively
// evaluating the function calls.
// This also needs to be done if the function call has a receiver
// argument or a closure address (because those addresses could be on the stack
// and have changed position between the start of the call and now).
err := funcCallEvalFuncExpr(callScope, fncall, true)
if err != nil {
fncall.err = err
fncall.lateCallFailure = true
break
}
//TODO: double check that function call size isn't too big
}
// instead of evaluating the arguments we start first by pushing the call
// on the stack, this is the opposite of what would happen normally but
// it's necessary because otherwise the GC wouldn't be able to deal with
// the argument frame.
if fncall.closureAddr != 0 {
// When calling a function pointer we must set the DX register to the
// address of the function pointer itself.
setClosureReg(thread, fncall.closureAddr)
}
cfa := regs.SP()
oldpc := regs.PC()
var oldlr uint64
if bi.Arch.Name == "arm64" {
oldlr = regs.LR()
}
callOP(bi, thread, regs, fncall.fn.Entry)
formalScope, err := GoroutineScope(callScope.target, thread)
if formalScope != nil && formalScope.Regs.CFA != int64(cfa) {
// This should never happen, checking just to avoid hard to figure out disasters.
err = fmt.Errorf("mismatch in CFA %#x (calculated) %#x (expected)", formalScope.Regs.CFA, int64(cfa))
}
if err == nil {
err = funcCallEvalArgs(callScope, fncall, formalScope)
}
if err != nil {
// rolling back the call, note: this works because we called regs.Copy() above
switch bi.Arch.Name {
case "amd64":
setSP(thread, cfa)
setPC(thread, oldpc)
case "arm64":
setLR(thread, oldlr)
setPC(thread, oldpc)
default:
panic("not implemented")
}
fncall.err = err
fncall.lateCallFailure = true
break
}
case debugCallRegRestoreRegisters: // 16
// runtime requests that we restore the registers (all except pc and sp),
// this is also the last step of the function call protocol.
pc, sp := regs.PC(), regs.SP()
if err := thread.RestoreRegisters(fncall.savedRegs); err != nil {
fncall.err = fmt.Errorf("could not restore registers: %v", err)
}
if err := setPC(thread, pc); err != nil {
fncall.err = fmt.Errorf("could not restore PC: %v", err)
}
if err := setSP(thread, sp); err != nil {
fncall.err = fmt.Errorf("could not restore SP: %v", err)
}
if err := stepInstructionOut(p, thread, debugCallName, debugCallName); err != nil {
fncall.err = fmt.Errorf("could not step out of %s: %v", debugCallName, err)
}
if bi.Arch.Name == "amd64" {
// The tail of debugCallV2 corrupts the state of RFLAGS, we must restore
// it one extra time after stepping out of it.
// See https://github.com/go-delve/delve/issues/2985 and
// TestCallInjectionFlagCorruption
rflags := bi.Arch.RegistersToDwarfRegisters(0, fncall.savedRegs).Uint64Val(regnum.AMD64_Rflags)
err := thread.SetReg(regnum.AMD64_Rflags, op.DwarfRegisterFromUint64(rflags))
if err != nil {
fncall.err = fmt.Errorf("could not restore RFLAGS register: %v", err)
}
}
return true
case debugCallRegReadReturn: // 1
// read return arguments from stack
if fncall.panicvar != nil || fncall.lateCallFailure {
break
}
retScope, err := ThreadScope(p, thread)
if err != nil {
fncall.err = fmt.Errorf("could not get return values: %v", err)
break
}
// pretend we are still inside the function we called
fakeFunctionEntryScope(retScope, fncall.fn, int64(regs.SP()), regs.SP()-uint64(bi.Arch.PtrSize()))
var flags localsFlags
flags |= localsNoDeclLineCheck // if the function we are calling is an autogenerated stub then declaration lines have no meaning
if !bi.regabi {
flags |= localsTrustArgOrder
}
fncall.retvars, err = retScope.Locals(flags)
if err != nil {
fncall.err = fmt.Errorf("could not get return values: %v", err)
break
}
fncall.retvars = filterVariables(fncall.retvars, func(v *Variable) bool {
return (v.Flags & VariableReturnArgument) != 0
})
loadValues(fncall.retvars, callScope.callCtx.retLoadCfg)
for _, v := range fncall.retvars {
v.Flags |= VariableFakeAddress
}
// Store the stack span of the currently running goroutine (which in Go >=
// 1.15 might be different from the original injection goroutine) so that
// later on we can use it to perform the escapeCheck
if threadg, _ := GetG(thread); threadg != nil {
callScope.callCtx.stacks = append(callScope.callCtx.stacks, threadg.stack)
}
if bi.Arch.Name == "arm64" {
oldlr, err := readUintRaw(thread.ProcessMemory(), regs.SP(), int64(bi.Arch.PtrSize()))
if err != nil {
fncall.err = fmt.Errorf("could not restore LR: %v", err)
break
}