before unload module, unregister itab from itabList, otherwise, there will be panic when the itabList grow

Author: pkujhd

Diff for: dymcode.go

@@ -535,6 +535,9 @@ func Load(code *CodeReloc, symPtr map[string]uintptr) (*CodeModule, error) {
 }
 
 func (cm *CodeModule) Unload() {
+	for i := 0; i < len(cm.itabs); i++ {
+		eraseiface(cm.itabs[i].inter, cm.itabs[i]._type)
+	}
 	runtime.GC()
 	modulesLock.Lock()
 	removeModule(cm.Module)

Diff for: iface.1.10.go

@@ -0,0 +1,62 @@
+// +build go1.10
+// +build !go1.15
+
+package goloader
+
+import (
+	"unsafe"
+)
+
+// layout of Itab known to compilers
+// allocated in non-garbage-collected memory
+// Needs to be in sync with
+// ../cmd/compile/internal/gc/reflect.go:/^func.dumptabs.
+type itab struct {
+	inter *interfacetype
+	_type *_type
+	hash  uint32 // copy of _type.hash. Used for type switches.
+	_     [4]byte
+	fun   [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
+}
+
+const itabInitSize = 512
+
+// Note: change the formula in the mallocgc call in itabAdd if you change these fields.
+type itabTableType struct {
+	size    uintptr             // length of entries array. Always a power of 2.
+	count   uintptr             // current number of filled entries.
+	entries [itabInitSize]*itab // really [size] large
+}
+
+//go:linkname itabTable runtime.itabTable
+var itabTable *itabTableType // pointer to current table
+
+//go:linkname itabLock runtime.itabLock
+var itabLock mutex
+
+//go:linkname itabHashFunc runtime.itabHashFunc
+func itabHashFunc(inter *interfacetype, typ *_type) uintptr
+
+func eraseiface(inter *interfacetype, typ *_type) bool {
+	lock(&itabLock)
+	defer unlock(&itabLock)
+	mask := itabTable.size - 1
+	h := itabHashFunc(inter, typ) & mask
+	for i := uintptr(1); ; i++ {
+		p := (**itab)(add(unsafe.Pointer(&itabTable.entries), h*PtrSize))
+		// Use atomic read here so if we see m != nil, we also see
+		// the initializations of the fields of m.
+		// m := *p
+		m := (*itab)(Loadp(unsafe.Pointer(p)))
+		if m == nil {
+			return false
+		}
+		if m.inter == inter && m._type == typ {
+			atomicstorep(unsafe.Pointer(p), unsafe.Pointer(nil))
+			itabTable.count = itabTable.count - 1
+			return true
+		}
+		h += i
+		h &= mask
+	}
+}

Diff for: iface.1.8.go

@@ -0,0 +1,52 @@
+// +build go1.8
+// +build !go1.10,!go1.11,!go1.12,!go1.13,!go1.14,!go1.15
+
+package goloader
+
+import (
+	"unsafe"
+)
+
+// layout of Itab known to compilers
+// allocated in non-garbage-collected memory
+// Needs to be in sync with
+// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
+type itab struct {
+	inter  *interfacetype
+	_type  *_type
+	link   *itab
+	bad    int32
+	inhash int32      // has this itab been added to hash?
+	fun    [1]uintptr // variable sized
+}
+
+// See: src/runtime/iface.go
+const hashSize = 1009
+
+//go:linkname hash runtime.hash
+var hash [hashSize]*itab
+
+//go:linkname ifaceLock runtime.ifaceLock
+var ifaceLock mutex
+
+//go:linkname itabhash runtime.itabhash
+func itabhash(inter *interfacetype, typ *_type) uint32
+
+func eraseiface(inter *interfacetype, typ *_type) bool {
+	lock(&ifaceLock)
+	defer unlock(&ifaceLock)
+	h := itabhash(inter, typ)
+	var m, last *itab = nil, nil
+	for m = (*itab)(Loadp(unsafe.Pointer(&hash[h]))); m != nil; m = m.link {
+		if m.inter == inter && m._type == typ {
+			if last == nil {
+				atomicstorep(unsafe.Pointer(&hash[h]), unsafe.Pointer(nil))
+			} else {
+				last.link = m.link
+			}
+			return true
+		}
+		last = m
+	}
+	return false
+}

Diff for: iface.go

@@ -0,0 +1,23 @@
+package goloader
+
+import "unsafe"
+
+// Mutual exclusion locks.  In the uncontended case,
+// as fast as spin locks (just a few user-level instructions),
+// but on the contention path they sleep in the kernel.
+// A zeroed Mutex is unlocked (no need to initialize each lock).
+type mutex struct {
+	// Futex-based impl treats it as uint32 key,
+	// while sema-based impl as M* waitm.
+	// Used to be a union, but unions break precise GC.
+	key uintptr
+}
+
+//go:linkname lock runtime.lock
+func lock(l *mutex)
+
+//go:linkname unlock runtime.unlock
+func unlock(l *mutex)
+
+//go:linkname atomicstorep runtime.atomicstorep
+func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer)

Diff for: module.1.10.go

@@ -5,18 +5,6 @@ package goloader
 
 import "cmd/objfile/goobj"
 
-// layout of Itab known to compilers
-// allocated in non-garbage-collected memory
-// Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
-type itab struct {
-	inter *interfacetype
-	_type *_type
-	hash  uint32 // copy of _type.hash. Used for type switches.
-	_     [4]byte
-	fun   [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
-}
-
 // PCDATA and FUNCDATA table indexes.
 //
 // See funcdata.h and ../cmd/internal/obj/funcdata.go.

Diff for: module.1.12.go

@@ -9,18 +9,6 @@ import (
 	"strings"
 )
 
-// layout of Itab known to compilers
-// allocated in non-garbage-collected memory
-// Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
-type itab struct {
-	inter *interfacetype
-	_type *_type
-	hash  uint32 // copy of _type.hash. Used for type switches.
-	_     [4]byte
-	fun   [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
-}
-
 // PCDATA and FUNCDATA table indexes.
 //
 // See funcdata.h and ../cmd/internal/objabi/funcdata.go.

Diff for: module.1.13.go

@@ -9,18 +9,6 @@ import (
 	"strings"
 )
 
-// layout of Itab known to compilers
-// allocated in non-garbage-collected memory
-// Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
-type itab struct {
-	inter *interfacetype
-	_type *_type
-	hash  uint32 // copy of _type.hash. Used for type switches.
-	_     [4]byte
-	fun   [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
-}
-
 // PCDATA and FUNCDATA table indexes.
 //
 // See funcdata.h and ../cmd/internal/objabi/funcdata.go.

Diff for: module.1.14.go

@@ -9,18 +9,6 @@ import (
 	"strings"
 )
 
-// layout of Itab known to compilers
-// allocated in non-garbage-collected memory
-// Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.dumptabs.
-type itab struct {
-	inter *interfacetype
-	_type *_type
-	hash  uint32 // copy of _type.hash. Used for type switches.
-	_     [4]byte
-	fun   [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter.
-}
-
 // PCDATA and FUNCDATA table indexes.
 //
 // See funcdata.h and ../cmd/internal/objabi/funcdata.go.

Diff for: module.1.8.go

@@ -7,19 +7,6 @@ import (
 	"cmd/objfile/goobj"
 )
 
-// layout of Itab known to compilers
-// allocated in non-garbage-collected memory
-// Needs to be in sync with
-// ../cmd/compile/internal/gc/reflect.go:/^func.dumptypestructs.
-type itab struct {
-	inter  *interfacetype
-	_type  *_type
-	link   *itab
-	bad    int32
-	inhash int32      // has this itab been added to hash?
-	fun    [1]uintptr // variable sized
-}
-
 // PCDATA and FUNCDATA table indexes.
 //
 // See funcdata.h and ../cmd/internal/obj/funcdata.go.

Diff for: utils.go

@@ -40,3 +40,9 @@ func copy2Slice(dst []byte, src unsafe.Pointer, size int) {
 	}
 	copy(dst, *(*[]byte)(unsafe.Pointer(&s)))
 }
+
+//go:nosplit
+//go:noinline
+func Loadp(ptr unsafe.Pointer) unsafe.Pointer {
+	return *(*unsafe.Pointer)(ptr)
+}