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fix: data race in AnalyzeTypeAddr for v0.10.4 #531

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merged 1 commit into from
Jan 25, 2025
Merged

fix: data race in AnalyzeTypeAddr for v0.10.4 #531

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108 changes: 53 additions & 55 deletions internal/runtime/type.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package runtime

import (
"reflect"
"sync"
"unsafe"
)

Expand All @@ -23,8 +24,8 @@ type TypeAddr struct {
}

var (
typeAddr *TypeAddr
alreadyAnalyzed bool
typeAddr *TypeAddr
once sync.Once
)

//go:linkname typelinks reflect.typelinks
Expand All @@ -34,67 +35,64 @@ func typelinks() ([]unsafe.Pointer, [][]int32)
func rtypeOff(unsafe.Pointer, int32) unsafe.Pointer

func AnalyzeTypeAddr() *TypeAddr {
defer func() {
alreadyAnalyzed = true
}()
if alreadyAnalyzed {
return typeAddr
}
sections, offsets := typelinks()
if len(sections) != 1 {
return nil
}
if len(offsets) != 1 {
return nil
}
section := sections[0]
offset := offsets[0]
var (
min uintptr = uintptr(^uint(0))
max uintptr = 0
isAligned64 = true
isAligned32 = true
)
for i := 0; i < len(offset); i++ {
typ := (*Type)(rtypeOff(section, offset[i]))
addr := uintptr(unsafe.Pointer(typ))
if min > addr {
min = addr
once.Do(func() {
sections, offsets := typelinks()
if len(sections) != 1 {
return
}
if max < addr {
max = addr
if len(offsets) != 1 {
return
}
if typ.Kind() == reflect.Ptr {
addr = uintptr(unsafe.Pointer(typ.Elem()))
section := sections[0]
offset := offsets[0]
var (
min uintptr = uintptr(^uint(0))
max uintptr = 0
isAligned64 = true
isAligned32 = true
)
for i := 0; i < len(offset); i++ {
typ := (*Type)(rtypeOff(section, offset[i]))
addr := uintptr(unsafe.Pointer(typ))
if min > addr {
min = addr
}
if max < addr {
max = addr
}
if typ.Kind() == reflect.Ptr {
addr = uintptr(unsafe.Pointer(typ.Elem()))
if min > addr {
min = addr
}
if max < addr {
max = addr
}
}
isAligned64 = isAligned64 && (addr-min)&63 == 0
isAligned32 = isAligned32 && (addr-min)&31 == 0
}
addrRange := max - min
if addrRange == 0 {
return
}
var addrShift uintptr
if isAligned64 {
addrShift = 6
} else if isAligned32 {
addrShift = 5
}
isAligned64 = isAligned64 && (addr-min)&63 == 0
isAligned32 = isAligned32 && (addr-min)&31 == 0
}
addrRange := max - min
if addrRange == 0 {
return nil
}
var addrShift uintptr
if isAligned64 {
addrShift = 6
} else if isAligned32 {
addrShift = 5
}
cacheSize := addrRange >> addrShift
if cacheSize > maxAcceptableTypeAddrRange {
return nil
}
typeAddr = &TypeAddr{
BaseTypeAddr: min,
MaxTypeAddr: max,
AddrRange: addrRange,
AddrShift: addrShift,
}
cacheSize := addrRange >> addrShift
if cacheSize > maxAcceptableTypeAddrRange {
return
}
typeAddr = &TypeAddr{
BaseTypeAddr: min,
MaxTypeAddr: max,
AddrRange: addrRange,
AddrShift: addrShift,
}
})

return typeAddr
}
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