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-rw-r--r--src/pkg/runtime/extern.go3
-rw-r--r--src/pkg/runtime/malloc.h10
-rw-r--r--src/pkg/runtime/mfinal_test.go81
-rw-r--r--src/pkg/runtime/mgc0.c50
-rw-r--r--src/pkg/runtime/runtime.c1
-rw-r--r--src/pkg/runtime/runtime.h1
-rw-r--r--src/pkg/runtime/stack.c58
7 files changed, 181 insertions, 23 deletions
diff --git a/src/pkg/runtime/extern.go b/src/pkg/runtime/extern.go
index 30fc34c0ba..0c5041d38b 100644
--- a/src/pkg/runtime/extern.go
+++ b/src/pkg/runtime/extern.go
@@ -36,6 +36,9 @@ a comma-separated list of name=val pairs. Supported names are:
length of the pause. Setting gctrace=2 emits the same summary but also
repeats each collection.
+ gcdead: setting gcdead=1 causes the garbage collector to clobber all stack slots
+ that it thinks are dead.
+
scheddetail: setting schedtrace=X and scheddetail=1 causes the scheduler to emit
detailed multiline info every X milliseconds, describing state of the scheduler,
processors, threads and goroutines.
diff --git a/src/pkg/runtime/malloc.h b/src/pkg/runtime/malloc.h
index ca6289174e..97b5a924fe 100644
--- a/src/pkg/runtime/malloc.h
+++ b/src/pkg/runtime/malloc.h
@@ -606,8 +606,14 @@ struct StackMap
enum {
// Pointer map
BitsPerPointer = 2,
- BitsNoPointer = 0,
- BitsPointer = 1,
+ BitsDead = 0,
+ BitsScalar = 1,
+ BitsPointer = 2,
+ BitsMultiWord = 3,
+ // BitsMultiWord will be set for the first word of a multi-word item.
+ // When it is set, one of the following will be set for the second word.
+ BitsString = 0,
+ BitsSlice = 1,
BitsIface = 2,
BitsEface = 3,
};
diff --git a/src/pkg/runtime/mfinal_test.go b/src/pkg/runtime/mfinal_test.go
index 32f26a6b29..41213138d2 100644
--- a/src/pkg/runtime/mfinal_test.go
+++ b/src/pkg/runtime/mfinal_test.go
@@ -8,6 +8,7 @@ import (
"runtime"
"testing"
"time"
+ "unsafe"
)
type Tintptr *int // assignable to *int
@@ -135,3 +136,83 @@ func BenchmarkFinalizerRun(b *testing.B) {
}
})
}
+
+// One chunk must be exactly one sizeclass in size.
+// It should be a sizeclass not used much by others, so we
+// have a greater chance of finding adjacent ones.
+// size class 19: 320 byte objects, 25 per page, 1 page alloc at a time
+const objsize = 320
+
+type objtype [objsize]byte
+
+func adjChunks() (*objtype, *objtype) {
+ var s []*objtype
+
+ for {
+ c := new(objtype)
+ for _, d := range s {
+ if uintptr(unsafe.Pointer(c))+unsafe.Sizeof(*c) == uintptr(unsafe.Pointer(d)) {
+ return c, d
+ }
+ if uintptr(unsafe.Pointer(d))+unsafe.Sizeof(*c) == uintptr(unsafe.Pointer(c)) {
+ return d, c
+ }
+ }
+ s = append(s, c)
+ }
+}
+
+// Make sure an empty slice on the stack doesn't pin the next object in memory.
+func TestEmptySlice(t *testing.T) {
+ if true { // disable until bug 7564 is fixed.
+ return
+ }
+ x, y := adjChunks()
+
+ // the pointer inside xs points to y.
+ xs := x[objsize:] // change objsize to objsize-1 and the test passes
+
+ fin := make(chan bool, 1)
+ runtime.SetFinalizer(y, func(z *objtype) { fin <- true })
+ runtime.GC()
+ select {
+ case <-fin:
+ case <-time.After(4 * time.Second):
+ t.Errorf("finalizer of next object in memory didn't run")
+ }
+ xsglobal = xs // keep empty slice alive until here
+}
+
+var xsglobal []byte
+
+func adjStringChunk() (string, *objtype) {
+ b := make([]byte, objsize)
+ for {
+ s := string(b)
+ t := new(objtype)
+ p := *(*uintptr)(unsafe.Pointer(&s))
+ q := uintptr(unsafe.Pointer(t))
+ if p+objsize == q {
+ return s, t
+ }
+ }
+}
+
+// Make sure an empty string on the stack doesn't pin the next object in memory.
+func TestEmptyString(t *testing.T) {
+ x, y := adjStringChunk()
+
+ ss := x[objsize:] // change objsize to objsize-1 and the test passes
+ fin := make(chan bool, 1)
+ // set finalizer on string contents of y
+ runtime.SetFinalizer(y, func(z *objtype) { fin <- true })
+ runtime.GC()
+ select {
+ case <-fin:
+ case <-time.After(4 * time.Second):
+ t.Errorf("finalizer of next string in memory didn't run")
+ }
+ ssglobal = ss // keep 0-length string live until here
+}
+
+var ssglobal string
diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 166c52b2ad..04dd93608a 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -1489,6 +1489,7 @@ scanbitvector(byte *scanp, BitVector *bv, bool afterprologue, void *wbufp)
uintptr word, bits;
uint32 *wordp;
int32 i, remptrs;
+ byte *p;
wordp = bv->data;
for(remptrs = bv->n; remptrs > 0; remptrs -= 32) {
@@ -1500,11 +1501,52 @@ scanbitvector(byte *scanp, BitVector *bv, bool afterprologue, void *wbufp)
i /= BitsPerPointer;
for(; i > 0; i--) {
bits = word & 3;
- if(bits != BitsNoPointer && *(void**)scanp != nil)
- if(bits == BitsPointer)
+ switch(bits) {
+ case BitsDead:
+ if(runtime·debug.gcdead)
+ *(uintptr*)scanp = (uintptr)0x6969696969696969LL;
+ break;
+ case BitsScalar:
+ break;
+ case BitsPointer:
+ p = *(byte**)scanp;
+ if(p != nil)
enqueue1(wbufp, (Obj){scanp, PtrSize, 0});
- else
- scaninterfacedata(bits, scanp, afterprologue, wbufp);
+ break;
+ case BitsMultiWord:
+ p = *(byte**)scanp;
+ if(p != nil) {
+ word >>= BitsPerPointer;
+ scanp += PtrSize;
+ i--;
+ if(i == 0) {
+ // Get next chunk of bits
+ remptrs -= 32;
+ word = *wordp++;
+ if(remptrs < 32)
+ i = remptrs;
+ else
+ i = 32;
+ i /= BitsPerPointer;
+ }
+ switch(word & 3) {
+ case BitsString:
+ if(((String*)(scanp - PtrSize))->len != 0)
+ markonly(p);
+ break;
+ case BitsSlice:
+ if(((Slice*)(scanp - PtrSize))->cap < ((Slice*)(scanp - PtrSize))->len)
+ runtime·throw("slice capacity smaller than length");
+ if(((Slice*)(scanp - PtrSize))->cap != 0)
+ enqueue1(wbufp, (Obj){scanp - PtrSize, PtrSize, 0});
+ break;
+ case BitsIface:
+ case BitsEface:
+ scaninterfacedata(word & 3, scanp - PtrSize, afterprologue, wbufp);
+ break;
+ }
+ }
+ }
word >>= BitsPerPointer;
scanp += PtrSize;
}
diff --git a/src/pkg/runtime/runtime.c b/src/pkg/runtime/runtime.c
index 2198bc6850..d77ff08af4 100644
--- a/src/pkg/runtime/runtime.c
+++ b/src/pkg/runtime/runtime.c
@@ -314,6 +314,7 @@ static struct {
{"allocfreetrace", &runtime·debug.allocfreetrace},
{"efence", &runtime·debug.efence},
{"gctrace", &runtime·debug.gctrace},
+ {"gcdead", &runtime·debug.gcdead},
{"scheddetail", &runtime·debug.scheddetail},
{"schedtrace", &runtime·debug.schedtrace},
};
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 9cb6960c62..7bd45d1a24 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -578,6 +578,7 @@ struct DebugVars
int32 allocfreetrace;
int32 efence;
int32 gctrace;
+ int32 gcdead;
int32 scheddetail;
int32 schedtrace;
};
diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c
index c73991470e..6e5d9f1f58 100644
--- a/src/pkg/runtime/stack.c
+++ b/src/pkg/runtime/stack.c
@@ -354,7 +354,11 @@ adjustpointers(byte **scanp, BitVector *bv, AdjustInfo *adjinfo, Func *f)
if(StackDebug >= 4)
runtime·printf(" %p:%s:%p\n", &scanp[i], mapnames[bv->data[i / (32 / BitsPerPointer)] >> (i * BitsPerPointer & 31) & 3], scanp[i]);
switch(bv->data[i / (32 / BitsPerPointer)] >> (i * BitsPerPointer & 31) & 3) {
- case BitsNoPointer:
+ case BitsDead:
+ if(runtime·debug.gcdead)
+ scanp[i] = (byte*)0x6868686868686868LL;
+ break;
+ case BitsScalar:
break;
case BitsPointer:
p = scanp[i];
@@ -370,33 +374,53 @@ adjustpointers(byte **scanp, BitVector *bv, AdjustInfo *adjinfo, Func *f)
scanp[i] = p + delta;
}
break;
- case BitsEface:
- t = (Type*)scanp[i];
- if(t != nil && (t->size > PtrSize || (t->kind & KindNoPointers) == 0)) {
- p = scanp[i+1];
+ case BitsMultiWord:
+ switch(bv->data[(i+1) / (32 / BitsPerPointer)] >> ((i+1) * BitsPerPointer & 31) & 3) {
+ case BitsString:
+ // string referents are never on the stack, never need to be adjusted
+ i++; // skip len
+ break;
+ case BitsSlice:
+ p = scanp[i];
if(minp <= p && p < maxp) {
if(StackDebug >= 3)
- runtime·printf("adjust eface %p\n", p);
- if(t->size > PtrSize) // currently we always allocate such objects on the heap
- runtime·throw("large interface value found on stack");
- scanp[i+1] = p + delta;
+ runtime·printf("adjust slice %p\n", p);
+ scanp[i] = p + delta;
}
- }
- break;
- case BitsIface:
- tab = (Itab*)scanp[i];
- if(tab != nil) {
- t = tab->type;
- if(t->size > PtrSize || (t->kind & KindNoPointers) == 0) {
+ i += 2; // skip len, cap
+ break;
+ case BitsEface:
+ t = (Type*)scanp[i];
+ if(t != nil && (t->size > PtrSize || (t->kind & KindNoPointers) == 0)) {
p = scanp[i+1];
if(minp <= p && p < maxp) {
if(StackDebug >= 3)
- runtime·printf("adjust iface %p\n", p);
+ runtime·printf("adjust eface %p\n", p);
if(t->size > PtrSize) // currently we always allocate such objects on the heap
runtime·throw("large interface value found on stack");
scanp[i+1] = p + delta;
}
}
+ i++;
+ break;
+ case BitsIface:
+ tab = (Itab*)scanp[i];
+ if(tab != nil) {
+ t = tab->type;
+ //runtime·printf(" type=%p\n", t);
+ if(t->size > PtrSize || (t->kind & KindNoPointers) == 0) {
+ p = scanp[i+1];
+ if(minp <= p && p < maxp) {
+ if(StackDebug >= 3)
+ runtime·printf("adjust iface %p\n", p);
+ if(t->size > PtrSize) // currently we always allocate such objects on the heap
+ runtime·throw("large interface value found on stack");
+ scanp[i+1] = p + delta;
+ }
+ }
+ }
+ i++;
+ break;
}
break;
}
generated by cgit v1.3 (git 2.53.0) at 2026-04-16 09:27:55 +0000