reflect: add write barriers
Use typedmemmove, typedslicecopy, and adjust reflect.call
to execute the necessary write barriers.
Found with GODEBUG=wbshadow=2 mode.
Eventually that will run automatically, but right now
it still detects other missing write barriers.
Change-Id: Iec5b5b0c1be5589295e28e5228e37f1a92e07742
Reviewed-on: https://go-review.googlesource.com/2312
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/src/reflect/value.go b/src/reflect/value.go
index c34679d..652dee2 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -107,7 +107,7 @@
// TODO: pass safe boolean from valueInterface so
// we don't need to copy if safe==true?
c := unsafe_New(t)
- memmove(c, ptr, t.size)
+ typedmemmove(t, c, ptr)
ptr = c
}
e.word = ptr
@@ -412,7 +412,7 @@
addr := unsafe.Pointer(uintptr(args) + off)
v = v.assignTo("reflect.Value.Call", targ, addr)
if v.flag&flagIndir != 0 {
- memmove(addr, v.ptr, n)
+ typedmemmove(targ, addr, v.ptr)
} else {
*(*unsafe.Pointer)(addr) = v.ptr
}
@@ -420,7 +420,7 @@
}
// Call.
- call(fn, args, uint32(frametype.size), uint32(retOffset))
+ call(frametype, fn, args, uint32(frametype.size), uint32(retOffset))
// For testing; see TestCallMethodJump.
if callGC {
@@ -473,7 +473,7 @@
// and we cannot let f keep a reference to the stack frame
// after this function returns, not even a read-only reference.
v.ptr = unsafe_New(typ)
- memmove(v.ptr, addr, typ.size)
+ typedmemmove(typ, v.ptr, addr)
v.flag |= flagIndir
} else {
v.ptr = *(*unsafe.Pointer)(addr)
@@ -509,7 +509,7 @@
off += -off & uintptr(typ.align-1)
addr := unsafe.Pointer(uintptr(ptr) + off)
if v.flag&flagIndir != 0 {
- memmove(addr, v.ptr, typ.size)
+ typedmemmove(typ, addr, v.ptr)
} else {
*(*unsafe.Pointer)(addr) = v.ptr
}
@@ -603,10 +603,10 @@
// Copy in receiver and rest of args.
storeRcvr(rcvr, args)
- memmove(unsafe.Pointer(uintptr(args)+ptrSize), frame, argSize-ptrSize)
+ typedmemmovepartial(frametype, unsafe.Pointer(uintptr(args)+ptrSize), frame, ptrSize, argSize-ptrSize)
// Call.
- call(fn, args, uint32(frametype.size), uint32(retOffset))
+ call(frametype, fn, args, uint32(frametype.size), uint32(retOffset))
// Copy return values. On amd64p32, the beginning of return values
// is 64-bit aligned, so the caller's frame layout (which doesn't have
@@ -617,8 +617,11 @@
if runtime.GOARCH == "amd64p32" {
callerRetOffset = align(argSize-ptrSize, 8)
}
- memmove(unsafe.Pointer(uintptr(frame)+callerRetOffset),
- unsafe.Pointer(uintptr(args)+retOffset), frametype.size-retOffset)
+ typedmemmovepartial(frametype,
+ unsafe.Pointer(uintptr(frame)+callerRetOffset),
+ unsafe.Pointer(uintptr(args)+retOffset),
+ retOffset,
+ frametype.size-retOffset)
}
// funcName returns the name of f, for use in error messages.
@@ -1017,7 +1020,7 @@
// Copy result so future changes to the map
// won't change the underlying value.
c := unsafe_New(typ)
- memmove(c, e, typ.size)
+ typedmemmove(typ, c, e)
return Value{typ, c, fl | flagIndir}
} else {
return Value{typ, *(*unsafe.Pointer)(e), fl}
@@ -1055,7 +1058,7 @@
// Copy result so future changes to the map
// won't change the underlying value.
c := unsafe_New(keyType)
- memmove(c, key, keyType.size)
+ typedmemmove(keyType, c, key)
a[i] = Value{keyType, c, fl | flagIndir}
} else {
a[i] = Value{keyType, *(*unsafe.Pointer)(key), fl}
@@ -1301,7 +1304,7 @@
}
x = x.assignTo("reflect.Set", v.typ, target)
if x.flag&flagIndir != 0 {
- memmove(v.ptr, x.ptr, v.typ.size)
+ typedmemmove(v.typ, v.ptr, x.ptr)
} else {
*(*unsafe.Pointer)(v.ptr) = x.ptr
}
@@ -1815,27 +1818,23 @@
se := src.typ.Elem()
typesMustMatch("reflect.Copy", de, se)
- n := dst.Len()
- if sn := src.Len(); n > sn {
- n = sn
+ var ds, ss sliceHeader
+ if dk == Array {
+ ds.Data = dst.ptr
+ ds.Len = dst.Len()
+ ds.Cap = ds.Len
+ } else {
+ ds = *(*sliceHeader)(dst.ptr)
+ }
+ if sk == Array {
+ ss.Data = src.ptr
+ ss.Len = src.Len()
+ ss.Cap = ss.Len
+ } else {
+ ss = *(*sliceHeader)(src.ptr)
}
- // Copy via memmove.
- var da, sa unsafe.Pointer
- if dk == Array {
- da = dst.ptr
- } else {
- da = (*sliceHeader)(dst.ptr).Data
- }
- if src.flag&flagIndir == 0 {
- sa = unsafe.Pointer(&src.ptr)
- } else if sk == Array {
- sa = src.ptr
- } else {
- sa = (*sliceHeader)(src.ptr).Data
- }
- memmove(da, sa, uintptr(n)*de.Size())
- return n
+ return typedslicecopy(de.common(), ds, ss)
}
// A runtimeSelect is a single case passed to rselect.
@@ -2376,7 +2375,7 @@
if f&flagAddr != 0 {
// indirect, mutable word - make a copy
c := unsafe_New(t)
- memmove(c, ptr, t.size)
+ typedmemmove(t, c, ptr)
ptr = c
f &^= flagAddr
}
@@ -2425,12 +2424,29 @@
func mapiterkey(it unsafe.Pointer) (key unsafe.Pointer)
func mapiternext(it unsafe.Pointer)
func maplen(m unsafe.Pointer) int
-func call(fn, arg unsafe.Pointer, n uint32, retoffset uint32)
+
+// call calls fn with a copy of the n argument bytes pointed at by arg.
+// After fn returns, reflectcall copies n-retoffset result bytes
+// back into arg+retoffset before returning. If copying result bytes back,
+// the caller must pass the argument frame type as argtype, so that
+// call can execute appropriate write barriers during the copy.
+func call(argtype *rtype, fn, arg unsafe.Pointer, n uint32, retoffset uint32)
func ifaceE2I(t *rtype, src interface{}, dst unsafe.Pointer)
+// typedmemmove copies a value of type t to dst from src.
//go:noescape
-func memmove(adst, asrc unsafe.Pointer, n uintptr)
+func typedmemmove(t *rtype, dst, src unsafe.Pointer)
+
+// typedmemmovepartial is like typedmemmove but assumes that
+// dst and src point off bytes into the value and only copies size bytes.
+//go:noescape
+func typedmemmovepartial(t *rtype, dst, src unsafe.Pointer, off, size uintptr)
+
+// typedslicecopy copies a slice of elemType values from src to dst,
+// returning the number of elements copied.
+//go:noescape
+func typedslicecopy(elemType *rtype, dst, src sliceHeader) int
// Dummy annotation marking that the value x escapes,
// for use in cases where the reflect code is so clever that
