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runtime: consolidate stkframe and its methods into stkframe.go

Browse Source 
The stkframe struct and its methods are strewn across different source
files. Since they actually have a pretty coherent theme at this point,
migrate it all into a new file, stkframe.go. There are no code changes
in this CL.

For #54466, albeit rather indirectly.

Change-Id: Ibe53fc4b1106d131005e1c9d491be838a8f14211
Reviewed-on: https://go-review.googlesource.com/c/go/+/424516
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Auto-Submit: Austin Clements <austin@google.com>
This commit is contained in:
Austin Clements 2022-08-17 09:06:14 -04:00 committed by Gopher Robot
parent b91e373729
commit 35026f3732
4 changed files with 288 additions and 276 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
src/runtime/runtime2.go
View File

@ -985,55 +985,6 @@ type _panic struct {
goexit bool
}
// A stkframe holds information about a single physical stack frame.
type stkframe struct {
// fn is the function being run in this frame. If there is
// inlining, this is the outermost function.
fn funcInfo
// pc is the program counter within fn.
//
// The meaning of this is subtle:
//
// - Typically, this frame performed a regular function call
// and this is the return PC (just after the CALL
// instruction). In this case, pc-1 reflects the CALL
// instruction itself and is the correct source of symbolic
// information.
//
// - If this frame "called" sigpanic, then pc is the
// instruction that panicked, and pc is the correct address
// to use for symbolic information.
//
// - If this is the innermost frame, then PC is where
// execution will continue, but it may not be the
// instruction following a CALL. This may be from
// cooperative preemption, in which case this is the
// instruction after the call to morestack. Or this may be
// from a signal or an un-started goroutine, in which case
// PC could be any instruction, including the first
// instruction in a function. Conventionally, we use pc-1
// for symbolic information, unless pc == fn.entry(), in
// which case we use pc.
pc uintptr
// continpc is the PC where execution will continue in fn, or
// 0 if execution will not continue in this frame.
//
// This is usually the same as pc, unless this frame "called"
// sigpanic, in which case it's either the address of
// deferreturn or 0 if this frame will never execute again.
//
// This is the PC to use to look up GC liveness for this frame.
continpc uintptr
lr uintptr // program counter at caller aka link register
sp uintptr // stack pointer at pc
fp uintptr // stack pointer at caller aka frame pointer
varp uintptr // top of local variables
argp uintptr // pointer to function arguments
}
// ancestorInfo records details of where a goroutine was started.
type ancestorInfo struct {
pcs []uintptr // pcs from the stack of this goroutine

136
src/runtime/stack.go
View File

@ -1247,142 +1247,6 @@ func freeStackSpans() {
unlock(&stackLarge.lock)
}
// getStackMap returns the locals and arguments live pointer maps, and
// stack object list for frame.
func (frame *stkframe) getStackMap(cache *pcvalueCache, debug bool) (locals, args bitvector, objs []stackObjectRecord) {
targetpc := frame.continpc
if targetpc == 0 {
// Frame is dead. Return empty bitvectors.
return
}
f := frame.fn
pcdata := int32(-1)
if targetpc != f.entry() {
// Back up to the CALL. If we're at the function entry
// point, we want to use the entry map (-1), even if
// the first instruction of the function changes the
// stack map.
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, cache)
}
if pcdata == -1 {
// We do not have a valid pcdata value but there might be a
// stackmap for this function. It is likely that we are looking
// at the function prologue, assume so and hope for the best.
pcdata = 0
}
// Local variables.
size := frame.varp - frame.sp
var minsize uintptr
switch goarch.ArchFamily {
case goarch.ARM64:
minsize = sys.StackAlign
default:
minsize = sys.MinFrameSize
}
if size > minsize {
stackid := pcdata
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stkmap == nil || stkmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped locals ", hex(frame.varp-size), "+", hex(size), "\n")
throw("missing stackmap")
}
// If nbit == 0, there's no work to do.
if stkmap.nbit > 0 {
if stackid < 0 || stackid >= stkmap.n {
// don't know where we are
print("runtime: pcdata is ", stackid, " and ", stkmap.n, " locals stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
locals = stackmapdata(stkmap, stackid)
if stackDebug >= 3 && debug {
print(" locals ", stackid, "/", stkmap.n, " ", locals.n, " words ", locals.bytedata, "\n")
}
} else if stackDebug >= 3 && debug {
print(" no locals to adjust\n")
}
}
// Arguments. First fetch frame size and special-case argument maps.
var isReflect bool
args, isReflect = frame.argMapInternal()
if args.n > 0 && args.bytedata == nil {
// Non-empty argument frame, but not a special map.
// Fetch the argument map at pcdata.
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped args ", hex(frame.argp), "+", hex(args.n*goarch.PtrSize), "\n")
throw("missing stackmap")
}
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " args stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
if stackmap.nbit == 0 {
args.n = 0
} else {
args = stackmapdata(stackmap, pcdata)
}
}
// stack objects.
if (GOARCH == "amd64" || GOARCH == "arm64" || GOARCH == "ppc64" || GOARCH == "ppc64le" || GOARCH == "riscv64") &&
unsafe.Sizeof(abi.RegArgs{}) > 0 && isReflect {
// For reflect.makeFuncStub and reflect.methodValueCall,
// we need to fake the stack object record.
// These frames contain an internal/abi.RegArgs at a hard-coded offset.
// This offset matches the assembly code on amd64 and arm64.
objs = methodValueCallFrameObjs[:]
} else {
p := funcdata(f, _FUNCDATA_StackObjects)
if p != nil {
n := *(*uintptr)(p)
p = add(p, goarch.PtrSize)
r0 := (*stackObjectRecord)(noescape(p))
objs = unsafe.Slice(r0, int(n))
// Note: the noescape above is needed to keep
// getStackMap from "leaking param content:
// frame". That leak propagates up to getgcmask, then
// GCMask, then verifyGCInfo, which converts the stack
// gcinfo tests into heap gcinfo tests :(
}
}
return
}
var methodValueCallFrameObjs [1]stackObjectRecord // initialized in stackobjectinit
func stkobjinit() {
var abiRegArgsEface any = abi.RegArgs{}
abiRegArgsType := efaceOf(&abiRegArgsEface)._type
if abiRegArgsType.kind&kindGCProg != 0 {
throw("abiRegArgsType needs GC Prog, update methodValueCallFrameObjs")
}
// Set methodValueCallFrameObjs[0].gcdataoff so that
// stackObjectRecord.gcdata() will work correctly with it.
ptr := uintptr(unsafe.Pointer(&methodValueCallFrameObjs[0]))
var mod *moduledata
for datap := &firstmoduledata; datap != nil; datap = datap.next {
if datap.gofunc <= ptr && ptr < datap.end {
mod = datap
break
}
}
if mod == nil {
throw("methodValueCallFrameObjs is not in a module")
}
methodValueCallFrameObjs[0] = stackObjectRecord{
off: -int32(alignUp(abiRegArgsType.size, 8)), // It's always the highest address local.
size: int32(abiRegArgsType.size),
_ptrdata: int32(abiRegArgsType.ptrdata),
gcdataoff: uint32(uintptr(unsafe.Pointer(abiRegArgsType.gcdata)) - mod.rodata),
}
}
// A stackObjectRecord is generated by the compiler for each stack object in a stack frame.
// This record must match the generator code in cmd/compile/internal/liveness/plive.go:emitStackObjects.
type stackObjectRecord struct {

288
src/runtime/stkframe.go Normal file
View File

@ -0,0 +1,288 @@
// 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.
package runtime
import (
"internal/abi"
"internal/goarch"
"runtime/internal/sys"
"unsafe"
)
// A stkframe holds information about a single physical stack frame.
type stkframe struct {
// fn is the function being run in this frame. If there is
// inlining, this is the outermost function.
fn funcInfo
// pc is the program counter within fn.
//
// The meaning of this is subtle:
//
// - Typically, this frame performed a regular function call
// and this is the return PC (just after the CALL
// instruction). In this case, pc-1 reflects the CALL
// instruction itself and is the correct source of symbolic
// information.
//
// - If this frame "called" sigpanic, then pc is the
// instruction that panicked, and pc is the correct address
// to use for symbolic information.
//
// - If this is the innermost frame, then PC is where
// execution will continue, but it may not be the
// instruction following a CALL. This may be from
// cooperative preemption, in which case this is the
// instruction after the call to morestack. Or this may be
// from a signal or an un-started goroutine, in which case
// PC could be any instruction, including the first
// instruction in a function. Conventionally, we use pc-1
// for symbolic information, unless pc == fn.entry(), in
// which case we use pc.
pc uintptr
// continpc is the PC where execution will continue in fn, or
// 0 if execution will not continue in this frame.
//
// This is usually the same as pc, unless this frame "called"
// sigpanic, in which case it's either the address of
// deferreturn or 0 if this frame will never execute again.
//
// This is the PC to use to look up GC liveness for this frame.
continpc uintptr
lr uintptr // program counter at caller aka link register
sp uintptr // stack pointer at pc
fp uintptr // stack pointer at caller aka frame pointer
varp uintptr // top of local variables
argp uintptr // pointer to function arguments
}
// reflectMethodValue is a partial duplicate of reflect.makeFuncImpl
// and reflect.methodValue.
type reflectMethodValue struct {
fn uintptr
stack *bitvector // ptrmap for both args and results
argLen uintptr // just args
}
// argBytes returns the argument frame size for a call to frame.fn.
func (frame *stkframe) argBytes() uintptr {
if frame.fn.args != _ArgsSizeUnknown {
return uintptr(frame.fn.args)
}
// This is an uncommon and complicated case. Fall back to fully
// fetching the argument map to compute its size.
argMap, _ := frame.argMapInternal()
return uintptr(argMap.n) * goarch.PtrSize
}
// argMapInternal is used internally by stkframe to fetch special
// argument maps.
//
// argMap.n is always populated with the size of the argument map.
//
// argMap.bytedata is only populated for dynamic argument maps (used
// by reflect). If the caller requires the argument map, it should use
// this if non-nil, and otherwise fetch the argument map using the
// current PC.
//
// hasReflectStackObj indicates that this frame also has a reflect
// function stack object, which the caller must synthesize.
func (frame *stkframe) argMapInternal() (argMap bitvector, hasReflectStackObj bool) {
f := frame.fn
argMap.n = f.args / goarch.PtrSize
if f.args == _ArgsSizeUnknown {
// Extract argument bitmaps for reflect stubs from the calls they made to reflect.
switch funcname(f) {
case "reflect.makeFuncStub", "reflect.methodValueCall":
// These take a *reflect.methodValue as their
// context register and immediately save it to 0(SP).
// Get the methodValue from 0(SP).
arg0 := frame.sp + sys.MinFrameSize
minSP := frame.fp
if !usesLR {
// The CALL itself pushes a word.
// Undo that adjustment.
minSP -= goarch.PtrSize
}
if arg0 >= minSP {
// The function hasn't started yet.
// This only happens if f was the
// start function of a new goroutine
// that hasn't run yet *and* f takes
// no arguments and has no results
// (otherwise it will get wrapped in a
// closure). In this case, we can't
// reach into its locals because it
// doesn't have locals yet, but we
// also know its argument map is
// empty.
if frame.pc != f.entry() {
print("runtime: confused by ", funcname(f), ": no frame (sp=", hex(frame.sp), " fp=", hex(frame.fp), ") at entry+", hex(frame.pc-f.entry()), "\n")
throw("reflect mismatch")
}
return bitvector{}, false // No locals, so also no stack objects
}
hasReflectStackObj = true
mv := *(**reflectMethodValue)(unsafe.Pointer(arg0))
// Figure out whether the return values are valid.
// Reflect will update this value after it copies
// in the return values.
retValid := *(*bool)(unsafe.Pointer(arg0 + 4*goarch.PtrSize))
if mv.fn != f.entry() {
print("runtime: confused by ", funcname(f), "\n")
throw("reflect mismatch")
}
argMap = *mv.stack
if !retValid {
// argMap.n includes the results, but
// those aren't valid, so drop them.
n := int32((uintptr(mv.argLen) &^ (goarch.PtrSize - 1)) / goarch.PtrSize)
if n < argMap.n {
argMap.n = n
}
}
}
}
return
}
// getStackMap returns the locals and arguments live pointer maps, and
// stack object list for frame.
func (frame *stkframe) getStackMap(cache *pcvalueCache, debug bool) (locals, args bitvector, objs []stackObjectRecord) {
targetpc := frame.continpc
if targetpc == 0 {
// Frame is dead. Return empty bitvectors.
return
}
f := frame.fn
pcdata := int32(-1)
if targetpc != f.entry() {
// Back up to the CALL. If we're at the function entry
// point, we want to use the entry map (-1), even if
// the first instruction of the function changes the
// stack map.
targetpc--
pcdata = pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, cache)
}
if pcdata == -1 {
// We do not have a valid pcdata value but there might be a
// stackmap for this function. It is likely that we are looking
// at the function prologue, assume so and hope for the best.
pcdata = 0
}
// Local variables.
size := frame.varp - frame.sp
var minsize uintptr
switch goarch.ArchFamily {
case goarch.ARM64:
minsize = sys.StackAlign
default:
minsize = sys.MinFrameSize
}
if size > minsize {
stackid := pcdata
stkmap := (*stackmap)(funcdata(f, _FUNCDATA_LocalsPointerMaps))
if stkmap == nil || stkmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped locals ", hex(frame.varp-size), "+", hex(size), "\n")
throw("missing stackmap")
}
// If nbit == 0, there's no work to do.
if stkmap.nbit > 0 {
if stackid < 0 || stackid >= stkmap.n {
// don't know where we are
print("runtime: pcdata is ", stackid, " and ", stkmap.n, " locals stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
locals = stackmapdata(stkmap, stackid)
if stackDebug >= 3 && debug {
print(" locals ", stackid, "/", stkmap.n, " ", locals.n, " words ", locals.bytedata, "\n")
}
} else if stackDebug >= 3 && debug {
print(" no locals to adjust\n")
}
}
// Arguments. First fetch frame size and special-case argument maps.
var isReflect bool
args, isReflect = frame.argMapInternal()
if args.n > 0 && args.bytedata == nil {
// Non-empty argument frame, but not a special map.
// Fetch the argument map at pcdata.
stackmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
if stackmap == nil || stackmap.n <= 0 {
print("runtime: frame ", funcname(f), " untyped args ", hex(frame.argp), "+", hex(args.n*goarch.PtrSize), "\n")
throw("missing stackmap")
}
if pcdata < 0 || pcdata >= stackmap.n {
// don't know where we are
print("runtime: pcdata is ", pcdata, " and ", stackmap.n, " args stack map entries for ", funcname(f), " (targetpc=", hex(targetpc), ")\n")
throw("bad symbol table")
}
if stackmap.nbit == 0 {
args.n = 0
} else {
args = stackmapdata(stackmap, pcdata)
}
}
// stack objects.
if (GOARCH == "amd64" || GOARCH == "arm64" || GOARCH == "ppc64" || GOARCH == "ppc64le" || GOARCH == "riscv64") &&
unsafe.Sizeof(abi.RegArgs{}) > 0 && isReflect {
// For reflect.makeFuncStub and reflect.methodValueCall,
// we need to fake the stack object record.
// These frames contain an internal/abi.RegArgs at a hard-coded offset.
// This offset matches the assembly code on amd64 and arm64.
objs = methodValueCallFrameObjs[:]
} else {
p := funcdata(f, _FUNCDATA_StackObjects)
if p != nil {
n := *(*uintptr)(p)
p = add(p, goarch.PtrSize)
r0 := (*stackObjectRecord)(noescape(p))
objs = unsafe.Slice(r0, int(n))
// Note: the noescape above is needed to keep
// getStackMap from "leaking param content:
// frame". That leak propagates up to getgcmask, then
// GCMask, then verifyGCInfo, which converts the stack
// gcinfo tests into heap gcinfo tests :(
}
}
return
}
var methodValueCallFrameObjs [1]stackObjectRecord // initialized in stackobjectinit
func stkobjinit() {
var abiRegArgsEface any = abi.RegArgs{}
abiRegArgsType := efaceOf(&abiRegArgsEface)._type
if abiRegArgsType.kind&kindGCProg != 0 {
throw("abiRegArgsType needs GC Prog, update methodValueCallFrameObjs")
}
// Set methodValueCallFrameObjs[0].gcdataoff so that
// stackObjectRecord.gcdata() will work correctly with it.
ptr := uintptr(unsafe.Pointer(&methodValueCallFrameObjs[0]))
var mod *moduledata
for datap := &firstmoduledata; datap != nil; datap = datap.next {
if datap.gofunc <= ptr && ptr < datap.end {
mod = datap
break
}
}
if mod == nil {
throw("methodValueCallFrameObjs is not in a module")
}
methodValueCallFrameObjs[0] = stackObjectRecord{
off: -int32(alignUp(abiRegArgsType.size, 8)), // It's always the highest address local.
size: int32(abiRegArgsType.size),
_ptrdata: int32(abiRegArgsType.ptrdata),
gcdataoff: uint32(uintptr(unsafe.Pointer(abiRegArgsType.gcdata)) - mod.rodata),
}
}

91
src/runtime/traceback.go
View File

@ -648,97 +648,6 @@ printloop:
}
}
// reflectMethodValue is a partial duplicate of reflect.makeFuncImpl
// and reflect.methodValue.
type reflectMethodValue struct {
fn uintptr
stack *bitvector // ptrmap for both args and results
argLen uintptr // just args
}
// argBytes returns the argument frame size for a call to frame.fn.
func (frame *stkframe) argBytes() uintptr {
if frame.fn.args != _ArgsSizeUnknown {
return uintptr(frame.fn.args)
}
// This is an uncommon and complicated case. Fall back to fully
// fetching the argument map to compute its size.
argMap, _ := frame.argMapInternal()
return uintptr(argMap.n) * goarch.PtrSize
}
// argMapInternal is used internally by stkframe to fetch special
// argument maps.
//
// argMap.n is always populated with the size of the argument map.
//
// argMap.bytedata is only populated for dynamic argument maps (used
// by reflect). If the caller requires the argument map, it should use
// this if non-nil, and otherwise fetch the argument map using the
// current PC.
//
// hasReflectStackObj indicates that this frame also has a reflect
// function stack object, which the caller must synthesize.
func (frame *stkframe) argMapInternal() (argMap bitvector, hasReflectStackObj bool) {
f := frame.fn
argMap.n = f.args / goarch.PtrSize
if f.args == _ArgsSizeUnknown {
// Extract argument bitmaps for reflect stubs from the calls they made to reflect.
switch funcname(f) {
case "reflect.makeFuncStub", "reflect.methodValueCall":
// These take a *reflect.methodValue as their
// context register and immediately save it to 0(SP).
// Get the methodValue from 0(SP).
arg0 := frame.sp + sys.MinFrameSize
minSP := frame.fp
if !usesLR {
// The CALL itself pushes a word.
// Undo that adjustment.
minSP -= goarch.PtrSize
}
if arg0 >= minSP {
// The function hasn't started yet.
// This only happens if f was the
// start function of a new goroutine
// that hasn't run yet *and* f takes
// no arguments and has no results
// (otherwise it will get wrapped in a
// closure). In this case, we can't
// reach into its locals because it
// doesn't have locals yet, but we
// also know its argument map is
// empty.
if frame.pc != f.entry() {
print("runtime: confused by ", funcname(f), ": no frame (sp=", hex(frame.sp), " fp=", hex(frame.fp), ") at entry+", hex(frame.pc-f.entry()), "\n")
throw("reflect mismatch")
}
return bitvector{}, false // No locals, so also no stack objects
}
hasReflectStackObj = true
mv := *(**reflectMethodValue)(unsafe.Pointer(arg0))
// Figure out whether the return values are valid.
// Reflect will update this value after it copies
// in the return values.
retValid := *(*bool)(unsafe.Pointer(arg0 + 4*goarch.PtrSize))
if mv.fn != f.entry() {
print("runtime: confused by ", funcname(f), "\n")
throw("reflect mismatch")
}
argMap = *mv.stack
if !retValid {
// argMap.n includes the results, but
// those aren't valid, so drop them.
n := int32((uintptr(mv.argLen) &^ (goarch.PtrSize - 1)) / goarch.PtrSize)
if n < argMap.n {
argMap.n = n
}
}
}
}
return
}
// tracebackCgoContext handles tracing back a cgo context value, from
// the context argument to setCgoTraceback, for the gentraceback
// function. It returns the new value of n.