// ptrTest is the tests without the boilerplate.
type ptrTest struct {
- c string // the cgo comment
- imports []string // a list of imports
- support string // supporting functions
- body string // the body of the main function
- fail bool // whether the test should fail
+ name string // for reporting
+ c string // the cgo comment
+ imports []string // a list of imports
+ support string // supporting functions
+ body string // the body of the main function
+ fail bool // whether the test should fail
+ expensive bool // whether the test requires the expensive check
}
var ptrTests = []ptrTest{
{
// Passing a pointer to a struct that contains a Go pointer.
+ name: "ptr1",
c: `typedef struct s { int *p; } s; void f(s *ps) {}`,
body: `C.f(&C.s{new(C.int)})`,
fail: true,
},
{
// Passing a pointer to a struct that contains a Go pointer.
+ name: "ptr2",
c: `typedef struct s { int *p; } s; void f(s *ps) {}`,
body: `p := &C.s{new(C.int)}; C.f(p)`,
fail: true,
{
// Passing a pointer to an int field of a Go struct
// that (irrelevantly) contains a Go pointer.
+ name: "ok1",
c: `struct s { int i; int *p; }; void f(int *p) {}`,
body: `p := &C.struct_s{i: 0, p: new(C.int)}; C.f(&p.i)`,
fail: false,
},
{
// Passing a pointer to a pointer field of a Go struct.
+ name: "ptr-field",
c: `struct s { int i; int *p; }; void f(int **p) {}`,
body: `p := &C.struct_s{i: 0, p: new(C.int)}; C.f(&p.p)`,
fail: true,
// Passing a pointer to a pointer field of a Go
// struct, where the field does not contain a Go
// pointer, but another field (irrelevantly) does.
+ name: "ptr-field-ok",
c: `struct s { int *p1; int *p2; }; void f(int **p) {}`,
body: `p := &C.struct_s{p1: nil, p2: new(C.int)}; C.f(&p.p1)`,
fail: false,
},
{
// Passing the address of a slice with no Go pointers.
+ name: "slice-ok-1",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `s := []unsafe.Pointer{nil}; C.f(&s[0])`,
},
{
// Passing the address of a slice with a Go pointer.
+ name: "slice-ptr-1",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{unsafe.Pointer(&i)}; C.f(&s[0])`,
// Passing the address of a slice with a Go pointer,
// where we are passing the address of an element that
// is not a Go pointer.
+ name: "slice-ptr-2",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{nil, unsafe.Pointer(&i)}; C.f(&s[0])`,
{
// Passing the address of a slice that is an element
// in a struct only looks at the slice.
+ name: "slice-ok-2",
c: `void f(void **p) {}`,
imports: []string{"unsafe"},
support: `type S struct { p *int; s []unsafe.Pointer }`,
{
// Passing the address of a static variable with no
// pointers doesn't matter.
+ name: "varok",
c: `void f(char** parg) {}`,
support: `var hello = [...]C.char{'h', 'e', 'l', 'l', 'o'}`,
body: `parg := [1]*C.char{&hello[0]}; C.f(&parg[0])`,
{
// Passing the address of a static variable with
// pointers does matter.
+ name: "var",
c: `void f(char*** parg) {}`,
support: `var hello = [...]*C.char{new(C.char)}`,
body: `parg := [1]**C.char{&hello[0]}; C.f(&parg[0])`,
fail: true,
},
+ {
+ // Storing a Go pointer into C memory should fail.
+ name: "barrier",
+ c: `#include <stdlib.h>
+ char **f1() { return malloc(sizeof(char*)); }
+ void f2(char **p) {}`,
+ body: `p := C.f1(); *p = new(C.char); C.f2(p)`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // Storing a Go pointer into C memory by assigning a
+ // large value should fail.
+ name: "barrier-struct",
+ c: `#include <stdlib.h>
+ struct s { char *a[10]; };
+ struct s *f1() { return malloc(sizeof(struct s)); }
+ void f2(struct s *p) {}`,
+ body: `p := C.f1(); p.a = [10]*C.char{new(C.char)}; C.f2(p)`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // Storing a Go pointer into C memory using a slice
+ // copy should fail.
+ name: "barrier-slice",
+ c: `#include <stdlib.h>
+ struct s { char *a[10]; };
+ struct s *f1() { return malloc(sizeof(struct s)); }
+ void f2(struct s *p) {}`,
+ body: `p := C.f1(); copy(p.a[:], []*C.char{new(C.char)}); C.f2(p)`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // A very large value uses a GC program, which is a
+ // different code path.
+ name: "barrier-gcprog-array",
+ c: `#include <stdlib.h>
+ struct s { char *a[32769]; };
+ struct s *f1() { return malloc(sizeof(struct s)); }
+ void f2(struct s *p) {}`,
+ body: `p := C.f1(); p.a = [32769]*C.char{new(C.char)}; C.f2(p)`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // Similar case, with a source on the heap.
+ name: "barrier-gcprog-array-heap",
+ c: `#include <stdlib.h>
+ struct s { char *a[32769]; };
+ struct s *f1() { return malloc(sizeof(struct s)); }
+ void f2(struct s *p) {}
+ void f3(void *p) {}`,
+ imports: []string{"unsafe"},
+ body: `p := C.f1(); n := &[32769]*C.char{new(C.char)}; p.a = *n; C.f2(p); n[0] = nil; C.f3(unsafe.Pointer(n))`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // A GC program with a struct.
+ name: "barrier-gcprog-struct",
+ c: `#include <stdlib.h>
+ struct s { char *a[32769]; };
+ struct s2 { struct s f; };
+ struct s2 *f1() { return malloc(sizeof(struct s2)); }
+ void f2(struct s2 *p) {}`,
+ body: `p := C.f1(); p.f = C.struct_s{[32769]*C.char{new(C.char)}}; C.f2(p)`,
+ fail: true,
+ expensive: true,
+ },
+ {
+ // Similar case, with a source on the heap.
+ name: "barrier-gcprog-struct-heap",
+ c: `#include <stdlib.h>
+ struct s { char *a[32769]; };
+ struct s2 { struct s f; };
+ struct s2 *f1() { return malloc(sizeof(struct s2)); }
+ void f2(struct s2 *p) {}
+ void f3(void *p) {}`,
+ imports: []string{"unsafe"},
+ body: `p := C.f1(); n := &C.struct_s{[32769]*C.char{new(C.char)}}; p.f = *n; C.f2(p); n.a[0] = nil; C.f3(unsafe.Pointer(n))`,
+ fail: true,
+ expensive: true,
+ },
}
func main() {
return false
}
+ ok := true
+
cmd := exec.Command("go", "run", name)
cmd.Dir = dir
+
+ if t.expensive {
+ cmd.Env = cgocheckEnv("1")
+ buf, err := cmd.CombinedOutput()
+ if err != nil {
+ var errbuf bytes.Buffer
+ if t.fail {
+ fmt.Fprintf(&errbuf, "test %s marked expensive but failed when not expensive: %v\n", t.name, err)
+ } else {
+ fmt.Fprintf(&errbuf, "test %s failed unexpectedly with GODEBUG=cgocheck=1: %v\n", t.name, err)
+ }
+ reportTestOutput(&errbuf, t.name, buf)
+ os.Stderr.Write(errbuf.Bytes())
+ ok = false
+ }
+
+ cmd = exec.Command("go", "run", name)
+ cmd.Dir = dir
+ }
+
+ if t.expensive {
+ cmd.Env = cgocheckEnv("2")
+ }
+
buf, err := cmd.CombinedOutput()
- ok := true
if t.fail {
if err == nil {
var errbuf bytes.Buffer
- fmt.Fprintf(&errbuf, "test %d did not fail as expected\n", i)
- reportTestOutput(&errbuf, i, buf)
+ fmt.Fprintf(&errbuf, "test %s did not fail as expected\n", t.name)
+ reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
} else if !bytes.Contains(buf, []byte("Go pointer")) {
var errbuf bytes.Buffer
- fmt.Fprintf(&errbuf, "test %d output does not contain expected error\n", i)
- reportTestOutput(&errbuf, i, buf)
+ fmt.Fprintf(&errbuf, "test %s output does not contain expected error (failed with %v)\n", t.name, err)
+ reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
} else {
if err != nil {
var errbuf bytes.Buffer
- fmt.Fprintf(&errbuf, "test %d failed unexpectedly: %v\n", i, err)
- reportTestOutput(&errbuf, i, buf)
+ fmt.Fprintf(&errbuf, "test %s failed unexpectedly: %v\n", t.name, err)
+ reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
+
+ if !t.expensive && ok {
+ // Make sure it passes with the expensive checks.
+ cmd := exec.Command("go", "run", name)
+ cmd.Dir = dir
+ cmd.Env = cgocheckEnv("2")
+ buf, err := cmd.CombinedOutput()
+ if err != nil {
+ var errbuf bytes.Buffer
+ fmt.Fprintf(&errbuf, "test %s failed unexpectedly with expensive checks: %v\n", t.name, err)
+ reportTestOutput(&errbuf, t.name, buf)
+ os.Stderr.Write(errbuf.Bytes())
+ ok = false
+ }
+ }
}
if t.fail && ok {
cmd = exec.Command("go", "run", name)
cmd.Dir = dir
- env := []string{"GODEBUG=cgocheck=0"}
- for _, e := range os.Environ() {
- if !strings.HasPrefix(e, "GODEBUG=") {
- env = append(env, e)
- }
- }
- cmd.Env = env
+ cmd.Env = cgocheckEnv("0")
buf, err := cmd.CombinedOutput()
if err != nil {
var errbuf bytes.Buffer
- fmt.Fprintf(&errbuf, "test %d failed unexpectedly with GODEBUG=cgocheck=0: %v\n", i, err)
- reportTestOutput(&errbuf, i, buf)
+ fmt.Fprintf(&errbuf, "test %s failed unexpectedly with GODEBUG=cgocheck=0: %v\n", t.name, err)
+ reportTestOutput(&errbuf, t.name, buf)
os.Stderr.Write(errbuf.Bytes())
ok = false
}
return ok
}
-func reportTestOutput(w io.Writer, i int, buf []byte) {
- fmt.Fprintf(w, "=== test %d output ===\n", i)
+func reportTestOutput(w io.Writer, name string, buf []byte) {
+ fmt.Fprintf(w, "=== test %s output ===\n", name)
fmt.Fprintf(w, "%s", buf)
- fmt.Fprintf(w, "=== end of test %d output ===\n", i)
+ fmt.Fprintf(w, "=== end of test %s output ===\n", name)
+}
+
+func cgocheckEnv(val string) []string {
+ env := []string{"GODEBUG=cgocheck=" + val}
+ for _, e := range os.Environ() {
+ if !strings.HasPrefix(e, "GODEBUG=") {
+ env = append(env, e)
+ }
+ }
+ return env
}
"func @\"\".chanrecv2 (@\"\".chanType·2 *byte, @\"\".hchan·3 <-chan any, @\"\".elem·4 *any) (? bool)\n" +
"func @\"\".chansend1 (@\"\".chanType·1 *byte, @\"\".hchan·2 chan<- any, @\"\".elem·3 *any)\n" +
"func @\"\".closechan (@\"\".hchan·1 any)\n" +
- "var @\"\".writeBarrierEnabled bool\n" +
+ "var @\"\".writeBarrier struct { @\"\".enabled bool; @\"\".needed bool; @\"\".cgo bool }\n" +
"func @\"\".writebarrierptr (@\"\".dst·1 *any, @\"\".src·2 any)\n" +
"func @\"\".writebarrierstring (@\"\".dst·1 *any, @\"\".src·2 any)\n" +
"func @\"\".writebarrierslice (@\"\".dst·1 *any, @\"\".src·2 any)\n" +
func chansend1(chanType *byte, hchan chan<- any, elem *any)
func closechan(hchan any)
-var writeBarrierEnabled bool
+var writeBarrier struct {
+ enabled bool
+ needed bool
+ cgo bool
+}
func writebarrierptr(dst *any, src any)
func writebarrierstring(dst *any, src any)
Cgenr(n, &src, nil)
}
- wbEnabled := syslook("writeBarrierEnabled", 0)
+ wbVar := syslook("writeBarrier", 0)
+ wbEnabled := Nod(ODOT, wbVar, newname(wbVar.Type.Type.Sym))
+ wbEnabled = typecheck(&wbEnabled, Erv)
pbr := Thearch.Ginscmp(ONE, Types[TUINT8], wbEnabled, Nodintconst(0), -1)
Thearch.Gins(Thearch.Optoas(OAS, Types[Tptr]), &src, &dst)
pjmp := Gbranch(obj.AJMP, nil, 0)
const cgoCheckPointerFail = "cgo argument has Go pointer to Go pointer"
-// cgoCheckArg is the real work of cgoCheckPointer. The argument p,
+// cgoCheckArg is the real work of cgoCheckPointer. The argument p
// is either a pointer to the value (of type t), or the value itself,
// depending on indir. The top parameter is whether we are at the top
// level, where Go pointers are allowed.
}
for i := uintptr(0); i < at.len; i++ {
cgoCheckArg(at.elem, p, true, top)
- p = unsafe.Pointer(uintptr(p) + at.elem.size)
+ p = add(p, at.elem.size)
}
case kindChan, kindMap:
// These types contain internal pointers that will
if inheap(uintptr(unsafe.Pointer(it))) {
panic(errorString(cgoCheckPointerFail))
}
- p = *(*unsafe.Pointer)(unsafe.Pointer(uintptr(p) + sys.PtrSize))
+ p = *(*unsafe.Pointer)(add(p, sys.PtrSize))
if !cgoIsGoPointer(p) {
return
}
}
for i := 0; i < s.cap; i++ {
cgoCheckArg(st.elem, p, true, false)
- p = unsafe.Pointer(uintptr(p) + st.elem.size)
+ p = add(p, st.elem.size)
}
case kindStruct:
st := (*structtype)(unsafe.Pointer(t))
return
}
for _, f := range st.fields {
- cgoCheckArg(f.typ, unsafe.Pointer(uintptr(p)+f.offset), true, top)
+ cgoCheckArg(f.typ, add(p, f.offset), true, top)
}
case kindPtr, kindUnsafePointer:
if indir {
// cgoIsGoPointer returns whether the pointer is a Go pointer--a
// pointer to Go memory. We only care about Go memory that might
// contain pointers.
+//go:nosplit
+//go:nowritebarrierrec
func cgoIsGoPointer(p unsafe.Pointer) bool {
if p == nil {
return false
}
// cgoInRange returns whether p is between start and end.
+//go:nosplit
+//go:nowritebarrierrec
func cgoInRange(p unsafe.Pointer, start, end uintptr) bool {
return start <= uintptr(p) && uintptr(p) < end
}
--- /dev/null
+// Copyright 2015 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.
+
+// Code to check that pointer writes follow the cgo rules.
+// These functions are invoked via the write barrier when debug.cgocheck > 1.
+
+package runtime
+
+import (
+ "runtime/internal/sys"
+ "unsafe"
+)
+
+const cgoWriteBarrierFail = "Go pointer stored into non-Go memory"
+
+// cgoCheckWriteBarrier is called whenever a pointer is stored into memory.
+// It throws if the program is storing a Go pointer into non-Go memory.
+//go:nosplit
+//go:nowritebarrier
+func cgoCheckWriteBarrier(dst *uintptr, src uintptr) {
+ if !cgoIsGoPointer(unsafe.Pointer(src)) {
+ return
+ }
+ if cgoIsGoPointer(unsafe.Pointer(dst)) {
+ return
+ }
+
+ // If we are running on the system stack then dst might be an
+ // address on the stack, which is OK.
+ g := getg()
+ if g == g.m.g0 || g == g.m.gsignal {
+ return
+ }
+
+ // Allocating memory can write to various mfixalloc structs
+ // that look like they are non-Go memory.
+ if g.m.mallocing != 0 {
+ return
+ }
+
+ systemstack(func() {
+ println("write of Go pointer", hex(src), "to non-Go memory", hex(uintptr(unsafe.Pointer(dst))))
+ throw(cgoWriteBarrierFail)
+ })
+}
+
+// cgoCheckMemmove is called when moving a block of memory.
+// dst and src point off bytes into the value to copy.
+// size is the number of bytes to copy.
+// It throws if the program is copying a block that contains a Go pointer
+// into non-Go memory.
+//go:nosplit
+//go:nowritebarrier
+func cgoCheckMemmove(typ *_type, dst, src unsafe.Pointer, off, size uintptr) {
+ if typ.kind&kindNoPointers != 0 {
+ return
+ }
+ if !cgoIsGoPointer(src) {
+ return
+ }
+ if cgoIsGoPointer(dst) {
+ return
+ }
+ cgoCheckTypedBlock(typ, src, off, size)
+}
+
+// cgoCheckSliceCopy is called when copying n elements of a slice from
+// src to dst. typ is the element type of the slice.
+// It throws if the program is copying slice elements that contain Go pointers
+// into non-Go memory.
+//go:nosplit
+//go:nowritebarrier
+func cgoCheckSliceCopy(typ *_type, dst, src slice, n int) {
+ if typ.kind&kindNoPointers != 0 {
+ return
+ }
+ if !cgoIsGoPointer(src.array) {
+ return
+ }
+ if cgoIsGoPointer(dst.array) {
+ return
+ }
+ p := src.array
+ for i := 0; i < n; i++ {
+ cgoCheckTypedBlock(typ, p, 0, typ.size)
+ p = add(p, typ.size)
+ }
+}
+
+// cgoCheckTypedBlock checks the block of memory at src, for up to size bytes,
+// and throws if it finds a Go pointer. The type of the memory is typ,
+// and src is off bytes into that type.
+//go:nosplit
+//go:nowritebarrier
+func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
+ if typ.kind&kindGCProg == 0 {
+ cgoCheckBits(src, typ.gcdata, off, size)
+ return
+ }
+
+ // The type has a GC program. Try to find GC bits somewhere else.
+ for datap := &firstmoduledata; datap != nil; datap = datap.next {
+ if cgoInRange(src, datap.data, datap.edata) {
+ doff := uintptr(src) - datap.data
+ cgoCheckBits(add(src, -doff), datap.gcdatamask.bytedata, off+doff, size)
+ return
+ }
+ if cgoInRange(src, datap.bss, datap.ebss) {
+ boff := uintptr(src) - datap.bss
+ cgoCheckBits(add(src, -boff), datap.gcbssmask.bytedata, off+boff, size)
+ return
+ }
+ }
+
+ aoff := uintptr(src) - mheap_.arena_start
+ idx := aoff >> _PageShift
+ s := h_spans[idx]
+ if s.state == _MSpanStack {
+ // There are no heap bits for value stored on the stack.
+ // For a channel receive src might be on the stack of some
+ // other goroutine, so we can't unwind the stack even if
+ // we wanted to.
+ // We can't expand the GC program without extra storage
+ // space we can't easily get.
+ // Fortunately we have the type information.
+ systemstack(func() {
+ cgoCheckUsingType(typ, src, off, size)
+ })
+ return
+ }
+
+ // src must be in the regular heap.
+
+ hbits := heapBitsForAddr(uintptr(src))
+ for i := uintptr(0); i < off+size; i += sys.PtrSize {
+ bits := hbits.bits()
+ if bits != 0 {
+ println(i, bits)
+ }
+ if i >= off && bits&bitPointer != 0 {
+ v := *(*unsafe.Pointer)(add(src, i))
+ if cgoIsGoPointer(v) {
+ systemstack(func() {
+ throw(cgoWriteBarrierFail)
+ })
+ }
+ }
+ hbits = hbits.next()
+ }
+}
+
+// cgoCheckBits checks the block of memory at src, for up to size
+// bytes, and throws if it finds a Go pointer. The gcbits mark each
+// pointer value. The src pointer is off bytes into the gcbits.
+//go:nosplit
+//go:nowritebarrier
+func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
+ skipMask := off / sys.PtrSize / 8
+ skipBytes := skipMask * sys.PtrSize * 8
+ ptrmask := addb(gcbits, skipMask)
+ src = add(src, skipBytes)
+ off -= skipBytes
+ size += off
+ var bits uint32
+ for i := uintptr(0); i < size; i += sys.PtrSize {
+ if i&(sys.PtrSize*8-1) == 0 {
+ bits = uint32(*ptrmask)
+ ptrmask = addb(ptrmask, 1)
+ } else {
+ bits >>= 1
+ }
+ if off > 0 {
+ off -= sys.PtrSize
+ } else {
+ if bits&1 != 0 {
+ v := *(*unsafe.Pointer)(add(src, i))
+ if cgoIsGoPointer(v) {
+ systemstack(func() {
+ throw(cgoWriteBarrierFail)
+ })
+ }
+ }
+ }
+ }
+}
+
+// cgoCheckUsingType is like cgoCheckTypedBlock, but is a last ditch
+// fall back to look for pointers in src using the type information.
+// We only this when looking at a value on the stack when the type
+// uses a GC program, because otherwise it's more efficient to use the
+// GC bits. This is called on the system stack.
+//go:nowritebarrier
+//go:systemstack
+func cgoCheckUsingType(typ *_type, src unsafe.Pointer, off, size uintptr) {
+ if typ.kind&kindNoPointers != 0 {
+ return
+ }
+ if typ.kind&kindGCProg == 0 {
+ cgoCheckBits(src, typ.gcdata, off, size)
+ return
+ }
+ switch typ.kind & kindMask {
+ default:
+ throw("can't happen")
+ case kindArray:
+ at := (*arraytype)(unsafe.Pointer(typ))
+ for i := uintptr(0); i < at.len; i++ {
+ if off < at.elem.size {
+ cgoCheckUsingType(at.elem, src, off, size)
+ }
+ src = add(src, at.elem.size)
+ skipped := off
+ if skipped > at.elem.size {
+ skipped = at.elem.size
+ }
+ checked := at.elem.size - skipped
+ off -= skipped
+ if size <= checked {
+ return
+ }
+ size -= checked
+ }
+ case kindStruct:
+ st := (*structtype)(unsafe.Pointer(typ))
+ for _, f := range st.fields {
+ if off < f.typ.size {
+ cgoCheckUsingType(f.typ, src, off, size)
+ }
+ src = add(src, f.typ.size)
+ skipped := off
+ if skipped > f.typ.size {
+ skipped = f.typ.size
+ }
+ checked := f.typ.size - skipped
+ off -= skipped
+ if size <= checked {
+ return
+ }
+ size -= checked
+ }
+ }
+}
allocfreetrace: setting allocfreetrace=1 causes every allocation to be
profiled and a stack trace printed on each object's allocation and free.
+ cgocheck: setting cgocheck=0 disables all checks for packages
+ using cgo to incorrectly pass Go pointers to non-Go code.
+ Setting cgocheck=1 (the default) enables relatively cheap
+ checks that may miss some errors. Setting cgocheck=2 enables
+ expensive checks that should not miss any errors, but will
+ cause your program to run slower.
+
efence: setting efence=1 causes the allocator to run in a mode
where each object is allocated on a unique page and addresses are
never recycled.
// white object dies before it is reached by the
// GC then the object can be collected during this GC cycle
// instead of waiting for the next cycle. Unfortunately the cost of
-// ensure that the object holding the slot doesn't concurrently
+// ensuring that the object holding the slot doesn't concurrently
// change to black without the mutator noticing seems prohibitive.
//
// Consider the following example where the mutator writes into
// stack frames that have not been active.
//go:nowritebarrierrec
func gcmarkwb_m(slot *uintptr, ptr uintptr) {
- if writeBarrierEnabled {
+ if writeBarrier.needed {
if ptr != 0 && inheap(ptr) {
shade(ptr)
}
//go:nosplit
func writebarrierptr(dst *uintptr, src uintptr) {
*dst = src
- if !writeBarrierEnabled {
+ if writeBarrier.cgo {
+ cgoCheckWriteBarrier(dst, src)
+ }
+ if !writeBarrier.needed {
return
}
if src != 0 && (src < sys.PhysPageSize || src == poisonStack) {
// Do not reapply.
//go:nosplit
func writebarrierptr_nostore(dst *uintptr, src uintptr) {
- if !writeBarrierEnabled {
+ if writeBarrier.cgo {
+ cgoCheckWriteBarrier(dst, src)
+ }
+ if !writeBarrier.needed {
return
}
if src != 0 && (src < sys.PhysPageSize || src == poisonStack) {
//go:nosplit
func typedmemmove(typ *_type, dst, src unsafe.Pointer) {
memmove(dst, src, typ.size)
+ if writeBarrier.cgo {
+ cgoCheckMemmove(typ, dst, src, 0, typ.size)
+ }
if typ.kind&kindNoPointers != 0 {
return
}
//go:linkname reflect_typedmemmovepartial reflect.typedmemmovepartial
func reflect_typedmemmovepartial(typ *_type, dst, src unsafe.Pointer, off, size uintptr) {
memmove(dst, src, size)
- if !writeBarrierEnabled || typ.kind&kindNoPointers != 0 || size < sys.PtrSize || !inheap(uintptr(dst)) {
+ if writeBarrier.cgo {
+ cgoCheckMemmove(typ, dst, src, off, size)
+ }
+ if !writeBarrier.needed || typ.kind&kindNoPointers != 0 || size < sys.PtrSize || !inheap(uintptr(dst)) {
return
}
// not to be preempted before the write barriers have been run.
//go:nosplit
func callwritebarrier(typ *_type, frame unsafe.Pointer, framesize, retoffset uintptr) {
- if !writeBarrierEnabled || typ == nil || typ.kind&kindNoPointers != 0 || framesize-retoffset < sys.PtrSize || !inheap(uintptr(frame)) {
+ if !writeBarrier.needed || typ == nil || typ.kind&kindNoPointers != 0 || framesize-retoffset < sys.PtrSize || !inheap(uintptr(frame)) {
return
}
heapBitsBulkBarrier(uintptr(add(frame, retoffset)), framesize-retoffset)
msanread(srcp, uintptr(n)*typ.size)
}
+ if writeBarrier.cgo {
+ cgoCheckSliceCopy(typ, dst, src, n)
+ }
+
// Note: No point in checking typ.kind&kindNoPointers here:
// compiler only emits calls to typedslicecopy for types with pointers,
// and growslice and reflect_typedslicecopy check for pointers
// before calling typedslicecopy.
- if !writeBarrierEnabled {
+ if !writeBarrier.needed {
memmove(dstp, srcp, uintptr(n)*typ.size)
return n
}
if (p|size)&(sys.PtrSize-1) != 0 {
throw("heapBitsBulkBarrier: unaligned arguments")
}
- if !writeBarrierEnabled {
+ if !writeBarrier.needed {
return
}
if !inheap(p) {
println("runtime: typeBitsBulkBarrier with type ", *typ._string, " with GC prog")
throw("runtime: invalid typeBitsBulkBarrier")
}
- if !writeBarrierEnabled {
+ if !writeBarrier.needed {
return
}
ptrmask := typ.gcdata
// Garbage collector phase.
// Indicates to write barrier and sychronization task to preform.
var gcphase uint32
-var writeBarrierEnabled bool // compiler emits references to this in write barriers
+
+// The compiler knows about this variable.
+// If you change it, you must change the compiler too.
+var writeBarrier struct {
+ enabled bool // compiler emits a check of this before calling write barrier
+ needed bool // whether we need a write barrier for current GC phase
+ cgo bool // whether we need a write barrier for a cgo check
+}
// gcBlackenEnabled is 1 if mutator assists and background mark
// workers are allowed to blacken objects. This must only be set when
//go:nosplit
func setGCPhase(x uint32) {
atomic.Store(&gcphase, x)
- writeBarrierEnabled = gcphase == _GCmark || gcphase == _GCmarktermination
+ writeBarrier.needed = gcphase == _GCmark || gcphase == _GCmarktermination
+ writeBarrier.enabled = writeBarrier.needed || writeBarrier.cgo
}
// gcMarkWorkerMode represents the mode that a concurrent mark worker
//
//go:nowritebarrier
func gcDrain(gcw *gcWork, flags gcDrainFlags) {
- if !writeBarrierEnabled {
+ if !writeBarrier.needed {
throw("gcDrain phase incorrect")
}
// increments. It returns the amount of scan work performed.
//go:nowritebarrier
func gcDrainN(gcw *gcWork, scanWork int64) int64 {
- if !writeBarrierEnabled {
+ if !writeBarrier.needed {
throw("gcDrainN phase incorrect")
}
if debug.gcstackbarrierall > 0 {
firstStackBarrierOffset = 0
}
+
+ // For cgocheck > 1, we turn on the write barrier at all times
+ // and check all pointer writes.
+ if debug.cgocheck > 1 {
+ writeBarrier.cgo = true
+ writeBarrier.enabled = true
+ }
}
// Poor mans 64-bit division.
} else {
// Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan uninitialized memory.
p = newarray(et, uintptr(newcap))
- if !writeBarrierEnabled {
+ if !writeBarrier.enabled {
memmove(p, old.array, lenmem)
} else {
for i := uintptr(0); i < lenmem; i += et.size {