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runtime: support register ABI Go functions from Windows callbacks

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This change modifies the system that allows Go functions to be set as
callbacks in various Windows systems to support the new register ABI.

For #40724.

Change-Id: Ie067f9e8a76c96d56177d7aa88f89cbe7223e12e
Reviewed-on: https://go-review.googlesource.com/c/go/+/300113
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Michael Anthony Knyszek 2021-03-09 21:13:34 +00:00 committed by Michael Knyszek
parent cb42e3e979
commit 44dd06670f
3 changed files with 306 additions and 82 deletions
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4
src/runtime/export_test.go
View File

@ -1233,7 +1233,9 @@ func (th *TimeHistogram) Record(duration int64) {
func SetIntArgRegs(a int) int {
lock(&finlock)
old := intArgRegs
intArgRegs = a
if a >= 0 {
intArgRegs = a
}
unlock(&finlock)
return old
}

279
src/runtime/syscall_windows.go
View File

@ -22,30 +22,178 @@ var cbs struct {
type winCallback struct {
fn *funcval // Go function
retPop uintptr // For 386 cdecl, how many bytes to pop on return
abiMap abiDesc
}
// abiPartKind is the action an abiPart should take.
type abiPartKind int
const (
abiPartBad abiPartKind = iota
abiPartStack // Move a value from memory to the stack.
abiPartReg // Move a value from memory to a register.
)
// abiPart encodes a step in translating between calling ABIs.
type abiPart struct {
kind abiPartKind
srcStackOffset uintptr
dstStackOffset uintptr // used if kind == abiPartStack
dstRegister int // used if kind == abiPartReg
len uintptr
}
func (a *abiPart) tryMerge(b abiPart) bool {
if a.kind != abiPartStack || b.kind != abiPartStack {
return false
}
if a.srcStackOffset+a.len == b.srcStackOffset && a.dstStackOffset+a.len == b.dstStackOffset {
a.len += b.len
return true
}
return false
}
// abiDesc specifies how to translate from a C frame to a Go
// frame. This does not specify how to translate back because
// the result is always a uintptr. If the C ABI is fastcall,
// this assumes the four fastcall registers were first spilled
// to the shadow space.
type abiDesc struct {
parts []abiPart
srcStackSize uintptr // stdcall/fastcall stack space tracking
dstStackSize uintptr // Go stack space used
dstRegisters int // Go ABI int argument registers used
// abiMap specifies how to translate from a C frame to a Go
// frame. This does not specify how to translate back because
// the result is always a uintptr. If the C ABI is fastcall,
// this assumes the four fastcall registers were first spilled
// to the shadow space.
abiMap []abiPart
// retOffset is the offset of the uintptr-sized result in the Go
// frame.
retOffset uintptr
}
// abiPart encodes a step in translating between calling ABIs.
type abiPart struct {
src, dst uintptr
len uintptr
func (p *abiDesc) assignArg(t *_type) {
if t.size > sys.PtrSize {
// We don't support this right now. In
// stdcall/cdecl, 64-bit ints and doubles are
// passed as two words (little endian); and
// structs are pushed on the stack. In
// fastcall, arguments larger than the word
// size are passed by reference. On arm,
// 8-byte aligned arguments round up to the
// next even register and can be split across
// registers and the stack.
panic("compileCallback: argument size is larger than uintptr")
}
if k := t.kind & kindMask; GOARCH != "386" && (k == kindFloat32 || k == kindFloat64) {
// In fastcall, floating-point arguments in
// the first four positions are passed in
// floating-point registers, which we don't
// currently spill. arm passes floating-point
// arguments in VFP registers, which we also
// don't support.
// So basically we only support 386.
panic("compileCallback: float arguments not supported")
}
if t.size == 0 {
// The Go ABI aligns for zero-sized types.
p.dstStackSize = alignUp(p.dstStackSize, uintptr(t.align))
return
}
// In the C ABI, we're already on a word boundary.
// Also, sub-word-sized fastcall register arguments
// are stored to the least-significant bytes of the
// argument word and all supported Windows
// architectures are little endian, so srcStackOffset
// is already pointing to the right place for smaller
// arguments. The same is true on arm.
oldParts := p.parts
if !p.tryRegAssignArg(t, 0) {
// Register assignment failed.
// Undo the work and stack assign.
p.parts = oldParts
// The Go ABI aligns arguments.
p.dstStackSize = alignUp(p.dstStackSize, uintptr(t.align))
// Copy just the size of the argument. Note that this
// could be a small by-value struct, but C and Go
// struct layouts are compatible, so we can copy these
// directly, too.
part := abiPart{
kind: abiPartStack,
srcStackOffset: p.srcStackSize,
dstStackOffset: p.dstStackSize,
len: t.size,
}
// Add this step to the adapter.
if len(p.parts) == 0 || !p.parts[len(p.parts)-1].tryMerge(part) {
p.parts = append(p.parts, part)
}
// The Go ABI packs arguments.
p.dstStackSize += t.size
}
// cdecl, stdcall, fastcall, and arm pad arguments to word size.
// TODO(rsc): On arm and arm64 do we need to skip the caller's saved LR?
p.srcStackSize += sys.PtrSize
}
func (a *abiPart) tryMerge(b abiPart) bool {
if a.src+a.len == b.src && a.dst+a.len == b.dst {
a.len += b.len
// tryRegAssignArg tries to register-assign a value of type t.
// If this type is nested in an aggregate type, then offset is the
// offset of this type within its parent type.
// Assumes t.size <= sys.PtrSize and t.size != 0.
//
// Returns whether the assignment succeeded.
func (p *abiDesc) tryRegAssignArg(t *_type, offset uintptr) bool {
switch k := t.kind & kindMask; k {
case kindBool, kindInt, kindInt8, kindInt16, kindInt32, kindUint, kindUint8, kindUint16, kindUint32, kindUintptr, kindPtr, kindUnsafePointer:
// Assign a register for all these types.
return p.assignReg(t.size, offset)
case kindInt64, kindUint64:
// Only register-assign if the registers are big enough.
if sys.PtrSize == 8 {
return p.assignReg(t.size, offset)
}
case kindArray:
at := (*arraytype)(unsafe.Pointer(t))
if at.len == 1 {
return p.tryRegAssignArg(at.elem, offset)
}
case kindStruct:
st := (*structtype)(unsafe.Pointer(t))
for i := range st.fields {
f := &st.fields[i]
if !p.tryRegAssignArg(f.typ, offset+f.offset()) {
return false
}
}
return true
}
return false
// Pointer-sized types such as maps and channels are currently
// not supported.
panic("compileCallabck: type " + t.string() + " is currently not supported for use in system callbacks")
}
// assignReg attempts to assign a single register for an
// argument with the given size, at the given offset into the
// value in the C ABI space.
//
// Returns whether the assignment was successful.
func (p *abiDesc) assignReg(size, offset uintptr) bool {
if p.dstRegisters >= intArgRegs {
return false
}
p.parts = append(p.parts, abiPart{
kind: abiPartReg,
srcStackOffset: p.srcStackSize + offset,
dstRegister: p.dstRegisters,
len: size,
})
p.dstRegisters++
return true
}
type winCallbackKey struct {
@ -101,62 +249,14 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
ft := (*functype)(unsafe.Pointer(fn._type))
// Check arguments and construct ABI translation.
var abiMap []abiPart
var src, dst uintptr
var abiMap abiDesc
for _, t := range ft.in() {
if t.size > sys.PtrSize {
// We don't support this right now. In
// stdcall/cdecl, 64-bit ints and doubles are
// passed as two words (little endian); and
// structs are pushed on the stack. In
// fastcall, arguments larger than the word
// size are passed by reference. On arm,
// 8-byte aligned arguments round up to the
// next even register and can be split across
// registers and the stack.
panic("compileCallback: argument size is larger than uintptr")
}
if k := t.kind & kindMask; GOARCH != "386" && (k == kindFloat32 || k == kindFloat64) {
// In fastcall, floating-point arguments in
// the first four positions are passed in
// floating-point registers, which we don't
// currently spill. arm passes floating-point
// arguments in VFP registers, which we also
// don't support.
// So basically we only support 386.
panic("compileCallback: float arguments not supported")
}
// The Go ABI aligns arguments.
dst = alignUp(dst, uintptr(t.align))
// In the C ABI, we're already on a word boundary.
// Also, sub-word-sized fastcall register arguments
// are stored to the least-significant bytes of the
// argument word and all supported Windows
// architectures are little endian, so src is already
// pointing to the right place for smaller arguments.
// The same is true on arm.
// Copy just the size of the argument. Note that this
// could be a small by-value struct, but C and Go
// struct layouts are compatible, so we can copy these
// directly, too.
part := abiPart{src, dst, t.size}
// Add this step to the adapter.
if len(abiMap) == 0 || !abiMap[len(abiMap)-1].tryMerge(part) {
abiMap = append(abiMap, part)
}
// cdecl, stdcall, fastcall, and arm pad arguments to word size.
// TODO(rsc): On arm and arm64 do we need to skip the caller's saved LR?
src += sys.PtrSize
// The Go ABI packs arguments.
dst += t.size
abiMap.assignArg(t)
}
// The Go ABI aligns the result to the word size. src is
// already aligned.
dst = alignUp(dst, sys.PtrSize)
retOffset := dst
abiMap.dstStackSize = alignUp(abiMap.dstStackSize, sys.PtrSize)
abiMap.retOffset = abiMap.dstStackSize
if len(ft.out()) != 1 {
panic("compileCallback: expected function with one uintptr-sized result")
@ -170,10 +270,14 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
// Either way, it's not AX.
panic("compileCallback: float results not supported")
}
// Make room for the uintptr-sized result.
dst += sys.PtrSize
if intArgRegs == 0 {
// Make room for the uintptr-sized result.
// If there are argument registers, the return value will
// be passed in the first register.
abiMap.dstStackSize += sys.PtrSize
}
if dst > callbackMaxFrame {
if abiMap.dstStackSize > callbackMaxFrame {
panic("compileCallback: function argument frame too large")
}
@ -181,7 +285,7 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
// arguments from the C stack.
var retPop uintptr
if cdecl {
retPop = src
retPop = abiMap.srcStackSize
}
key := winCallbackKey{(*funcval)(fn.data), cdecl}
@ -203,7 +307,7 @@ func compileCallback(fn eface, cdecl bool) (code uintptr) {
unlock(&cbs.lock)
throw("too many callback functions")
}
c := winCallback{key.fn, retPop, abiMap, retOffset}
c := winCallback{key.fn, retPop, abiMap}
cbs.ctxt[n] = c
cbs.index[key] = n
cbs.n++
@ -237,22 +341,39 @@ func callbackWrap(a *callbackArgs) {
a.retPop = c.retPop
// Convert from C to Go ABI.
var regs abi.RegArgs
var frame [callbackMaxFrame]byte
goArgs := unsafe.Pointer(&frame)
for _, part := range c.abiMap {
memmove(add(goArgs, part.dst), add(a.args, part.src), part.len)
for _, part := range c.abiMap.parts {
switch part.kind {
case abiPartStack:
memmove(add(goArgs, part.dstStackOffset), add(a.args, part.srcStackOffset), part.len)
case abiPartReg:
goReg := unsafe.Pointer(&regs.Ints[part.dstRegister])
memmove(goReg, add(a.args, part.srcStackOffset), part.len)
default:
panic("bad ABI description")
}
}
// Even though this is copying back results, we can pass a nil
// type because those results must not require write barriers.
//
// Pass a dummy RegArgs for now.
// TODO(mknyszek): Pass arguments in registers.
var regs abi.RegArgs
reflectcall(nil, unsafe.Pointer(c.fn), noescape(goArgs), uint32(c.retOffset)+sys.PtrSize, uint32(c.retOffset), uint32(c.retOffset)+sys.PtrSize, &regs)
reflectcall(nil, unsafe.Pointer(c.fn), noescape(goArgs), uint32(c.abiMap.dstStackSize), uint32(c.abiMap.retOffset), uint32(c.abiMap.dstStackSize), &regs)
// Extract the result.
a.result = *(*uintptr)(unsafe.Pointer(&frame[c.retOffset]))
//
// There's always exactly one return value, one pointer in size.
// If it's on the stack, then we will have reserved space for it
// at the end of the frame, otherwise it was passed in a register.
if c.abiMap.dstStackSize != c.abiMap.retOffset {
a.result = *(*uintptr)(unsafe.Pointer(&frame[c.abiMap.retOffset]))
} else {
var zero int
// On architectures with no registers, Ints[0] would be a compile error,
// so we use a dynamic index. These architectures will never take this
// branch, so this won't cause a runtime panic.
a.result = regs.Ints[zero]
}
}
const _LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800

105
src/runtime/syscall_windows_test.go
View File

@ -7,6 +7,7 @@ package runtime_test
import (
"bytes"
"fmt"
"internal/abi"
"internal/syscall/windows/sysdll"
"internal/testenv"
"io"
@ -390,6 +391,103 @@ var cbFuncs = []cbFunc{
}},
}
//go:registerparams
func sum2(i1, i2 uintptr) uintptr {
return i1 + i2
}
//go:registerparams
func sum3(i1, i2, i3 uintptr) uintptr {
return i1 + i2 + i3
}
//go:registerparams
func sum4(i1, i2, i3, i4 uintptr) uintptr {
return i1 + i2 + i3 + i4
}
//go:registerparams
func sum5(i1, i2, i3, i4, i5 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5
}
//go:registerparams
func sum6(i1, i2, i3, i4, i5, i6 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5 + i6
}
//go:registerparams
func sum7(i1, i2, i3, i4, i5, i6, i7 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5 + i6 + i7
}
//go:registerparams
func sum8(i1, i2, i3, i4, i5, i6, i7, i8 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8
}
//go:registerparams
func sum9(i1, i2, i3, i4, i5, i6, i7, i8, i9 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9
}
//go:registerparams
func sum10(i1, i2, i3, i4, i5, i6, i7, i8, i9, i10 uintptr) uintptr {
return i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9 + i10
}
//go:registerparams
func sum9uint8(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint8) uintptr {
return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}
//go:registerparams
func sum9uint16(i1, i2, i3, i4, i5, i6, i7, i8, i9 uint16) uintptr {
return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}
//go:registerparams
func sum9int8(i1, i2, i3, i4, i5, i6, i7, i8, i9 int8) uintptr {
return uintptr(i1 + i2 + i3 + i4 + i5 + i6 + i7 + i8 + i9)
}
//go:registerparams
func sum5mix(i1 int8, i2 int16, i3 int32, i4, i5 uintptr) uintptr {
return uintptr(i1) + uintptr(i2) + uintptr(i3) + i4 + i5
}
//go:registerparams
func sum5andPair(i1, i2, i3, i4, i5 uint8Pair) uintptr {
return uintptr(i1.x + i1.y + i2.x + i2.y + i3.x + i3.y + i4.x + i4.y + i5.x + i5.y)
}
// TODO(register args): Remove this once we switch to using the register
// calling convention by default, since this is redundant with the existing
// tests.
var cbFuncsRegABI = []cbFunc{
{sum2},
{sum3},
{sum4},
{sum5},
{sum6},
{sum7},
{sum8},
{sum9},
{sum10},
{sum9uint8},
{sum9uint16},
{sum9int8},
{sum5mix},
{sum5andPair},
}
func getCallbackTestFuncs() []cbFunc {
if regs := runtime.SetIntArgRegs(-1); regs > 0 {
return cbFuncsRegABI
}
return cbFuncs
}
type cbDLL struct {
name string
buildArgs func(out, src string) []string
@ -406,7 +504,7 @@ func (d *cbDLL) makeSrc(t *testing.T, path string) {
#include <stdint.h>
typedef struct { uint8_t x, y; } uint8Pair_t;
`)
for _, cbf := range cbFuncs {
for _, cbf := range getCallbackTestFuncs() {
cbf.cSrc(f, false)
cbf.cSrc(f, true)
}
@ -451,12 +549,15 @@ func TestStdcallAndCDeclCallbacks(t *testing.T) {
}
defer os.RemoveAll(tmp)
oldRegs := runtime.SetIntArgRegs(abi.IntArgRegs)
defer runtime.SetIntArgRegs(oldRegs)
for _, dll := range cbDLLs {
t.Run(dll.name, func(t *testing.T) {
dllPath := dll.build(t, tmp)
dll := syscall.MustLoadDLL(dllPath)
defer dll.Release()
for _, cbf := range cbFuncs {
for _, cbf := range getCallbackTestFuncs() {
t.Run(cbf.cName(false), func(t *testing.T) {
stdcall := syscall.NewCallback(cbf.goFunc)
cbf.testOne(t, dll, false, stdcall)