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internal/runtime/maps: cleanup seed usage

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Keep only a single seed; initialize it; and reset it when the map is
empty.

For #54766.

Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest-swissmap
Change-Id: Icc231f70957337a2d0dcd9c7daf9bd3cb4354d71
Reviewed-on: https://go-review.googlesource.com/c/go/+/616466
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Michael Pratt 2024-09-23 14:46:09 -04:00 committed by Gopher Robot
parent f782e16162
commit d95b7980aa
8 changed files with 46 additions and 54 deletions
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9
src/cmd/compile/internal/reflectdata/map_swiss.go
View File

@ -104,8 +104,6 @@ func swissTableType() *types.Type {
// localDepth uint8
// // N.B Padding
//
// seed uintptr
//
// index int
//
// // From groups.
@ -119,7 +117,6 @@ func swissTableType() *types.Type {
makefield("capacity", types.Types[types.TUINT16]),
makefield("growthLeft", types.Types[types.TUINT16]),
makefield("localDepth", types.Types[types.TUINT8]),
makefield("seed", types.Types[types.TUINTPTR]),
makefield("index", types.Types[types.TINT]),
makefield("groups_data", types.Types[types.TUNSAFEPTR]),
makefield("groups_lengthMask", types.Types[types.TUINT64]),
@ -134,9 +131,9 @@ func swissTableType() *types.Type {
table.SetUnderlying(types.NewStruct(fields))
types.CalcSize(table)
// The size of table should be 48 bytes on 64 bit
// and 36 bytes on 32 bit platforms.
if size := int64(3*2 + 2*1 /* one extra for padding */ + 2*8 + 3*types.PtrSize); table.Size() != size {
// The size of table should be 40 bytes on 64 bit
// and 32 bytes on 32 bit platforms.
if size := int64(3*2 + 2*1 /* one extra for padding */ + 2*8 + 2*types.PtrSize); table.Size() != size {
base.Fatalf("internal/runtime/maps.table size not correct: got %d, want %d", table.Size(), size)
}

17
src/internal/runtime/maps/map.go
View File

@ -197,7 +197,6 @@ type Map struct {
used uint64
// seed is the hash seed, computed as a unique random number per map.
// TODO(prattmic): Populate this on table initialization.
seed uintptr
// The directory of tables.
@ -293,10 +292,7 @@ func NewMap(mt *abi.SwissMapType, hint, maxAlloc uintptr) *Map {
}
m := &Map{
//TODO
//seed: uintptr(rand()),
//directory: make([]*table, dirSize),
seed: uintptr(rand()),
globalDepth: globalDepth,
globalShift: depthToShift(globalDepth),
@ -654,6 +650,13 @@ func (m *Map) Delete(typ *abi.SwissMapType, key unsafe.Pointer) {
m.directoryAt(idx).Delete(typ, m, key)
}
if m.used == 0 {
// Reset the hash seed to make it more difficult for attackers
// to repeatedly trigger hash collisions. See
// https://go.dev/issue/25237.
m.seed = uintptr(rand())
}
if m.writing == 0 {
fatal("concurrent map writes")
}
@ -735,6 +738,10 @@ func (m *Map) Clear(typ *abi.SwissMapType) {
// TODO: shrink directory?
}
// Reset the hash seed to make it more difficult for attackers to
// repeatedly trigger hash collisions. See https://go.dev/issue/25237.
m.seed = uintptr(rand())
if m.writing == 0 {
fatal("concurrent map writes")
}

8
src/internal/runtime/maps/runtime_fast32_swiss.go
View File

@ -259,7 +259,7 @@ outer:
if key == *(*uint32)(slotKey) {
slotElem = g.elem(typ, i)
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -297,7 +297,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
@ -400,7 +400,7 @@ outer:
if key == *(*unsafe.Pointer)(slotKey) {
slotElem = g.elem(typ, i)
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -438,7 +438,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}

8
src/internal/runtime/maps/runtime_fast64_swiss.go
View File

@ -259,7 +259,7 @@ outer:
if key == *(*uint64)(slotKey) {
slotElem = g.elem(typ, i)
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -297,7 +297,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
@ -438,7 +438,7 @@ outer:
if key == *(*unsafe.Pointer)(slotKey) {
slotElem = g.elem(typ, i)
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -476,7 +476,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}

4
src/internal/runtime/maps/runtime_faststr_swiss.go
View File

@ -266,7 +266,7 @@ outer:
*(*string)(slotKey) = key
slotElem = g.elem(typ, i)
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -304,7 +304,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}

4
src/internal/runtime/maps/runtime_swiss.go
View File

@ -269,7 +269,7 @@ outer:
slotElem = *((*unsafe.Pointer)(slotElem))
}
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}
match = match.removeFirst()
@ -317,7 +317,7 @@ outer:
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
break outer
}

30
src/internal/runtime/maps/table.go
View File

@ -51,10 +51,6 @@ type table struct {
// but this table has not yet been split.
localDepth uint8
// seed is the hash seed, computed as a unique random number per table.
// TODO(prattmic): Populate this on table initialization.
seed uintptr
// Index of this table in the Map directory. This is the index of the
// _first_ location in the directory. The table may occur in multiple
// sequential indicies.
@ -148,15 +144,15 @@ func (t *table) Used() uint64 {
// Get performs a lookup of the key that key points to. It returns a pointer to
// the element, or false if the key doesn't exist.
func (t *table) Get(typ *abi.SwissMapType, key unsafe.Pointer) (unsafe.Pointer, bool) {
func (t *table) Get(typ *abi.SwissMapType, m *Map, key unsafe.Pointer) (unsafe.Pointer, bool) {
// TODO(prattmic): We could avoid hashing in a variety of special
// cases.
//
// - One entry maps could just directly compare the single entry
// without hashing.
// - String keys could do quick checks of a few bytes before hashing.
hash := typ.Hasher(key, t.seed)
_, elem, ok := t.getWithKey(typ, hash, key)
hash := typ.Hasher(key, m.seed)
_, elem, ok := t.getWithKey(typ, hash, key)
return elem, ok
}
@ -299,7 +295,7 @@ func (t *table) PutSlot(typ *abi.SwissMapType, m *Map, hash uintptr, key unsafe.
slotElem = *((*unsafe.Pointer)(slotElem))
}
t.checkInvariants(typ)
t.checkInvariants(typ, m)
return slotElem, true
}
match = match.removeFirst()
@ -347,7 +343,7 @@ func (t *table) PutSlot(typ *abi.SwissMapType, m *Map, hash uintptr, key unsafe.
t.used++
m.used++
t.checkInvariants(typ)
t.checkInvariants(typ, m)
return slotElem, true
}
@ -425,7 +421,7 @@ func (t *table) uncheckedPutSlot(typ *abi.SwissMapType, hash uintptr, key unsafe
}
func (t *table) Delete(typ *abi.SwissMapType, m *Map, key unsafe.Pointer) {
hash := typ.Hasher(key, t.seed)
hash := typ.Hasher(key, m.seed)
seq := makeProbeSeq(h1(hash), t.groups.lengthMask)
for ; ; seq = seq.next() {
@ -482,7 +478,7 @@ func (t *table) Delete(typ *abi.SwissMapType, m *Map, key unsafe.Pointer) {
g.ctrls().set(i, ctrlDeleted)
}
t.checkInvariants(typ)
t.checkInvariants(typ, m)
return
}
match = match.removeFirst()
@ -514,12 +510,6 @@ func (t *table) Clear(typ *abi.SwissMapType) {
t.used = 0
t.resetGrowthLeft()
// Reset the hash seed to make it more difficult for attackers to
// repeatedly trigger hash collisions. See issue
// https://github.com/golang/go/issues/25237.
// TODO
//t.seed = uintptr(rand())
}
type Iter struct {
@ -948,7 +938,7 @@ func (t *table) split(typ *abi.SwissMapType, m *Map) {
elem = *((*unsafe.Pointer)(elem))
}
hash := typ.Hasher(key, t.seed)
hash := typ.Hasher(key, m.seed)
var newTable *table
if hash&mask == 0 {
newTable = left
@ -994,7 +984,7 @@ func (t *table) grow(typ *abi.SwissMapType, m *Map, newCapacity uint16) {
elem = *((*unsafe.Pointer)(elem))
}
hash := typ.Hasher(key, t.seed)
hash := typ.Hasher(key, m.seed)
// TODO(prattmic): For indirect key/elem, this is
// allocating new objects for key/elem. That is
@ -1007,7 +997,7 @@ func (t *table) grow(typ *abi.SwissMapType, m *Map, newCapacity uint16) {
}
}
newTable.checkInvariants(typ)
newTable.checkInvariants(typ, m)
m.replaceTable(newTable)
}

20
src/internal/runtime/maps/table_debug.go
View File

@ -12,7 +12,7 @@ import (
const debugLog = false
func (t *table) checkInvariants(typ *abi.SwissMapType) {
func (t *table) checkInvariants(typ *abi.SwissMapType, m *Map) {
if !debugLog {
return
}
@ -45,12 +45,12 @@ func (t *table) checkInvariants(typ *abi.SwissMapType) {
continue
}
if _, ok := t.Get(typ, key); !ok {
hash := typ.Hasher(key, t.seed)
if _, ok := t.Get(typ, m, key); !ok {
hash := typ.Hasher(key, m.seed)
print("invariant failed: slot(", i, "/", j, "): key ")
dump(key, typ.Key.Size_)
print(" not found [hash=", hash, ", h2=", h2(hash), " h1=", h1(hash), "]\n")
t.Print(typ)
t.Print(typ, m)
panic("invariant failed: slot: key not found")
}
}
@ -59,32 +59,30 @@ func (t *table) checkInvariants(typ *abi.SwissMapType) {
if used != t.used {
print("invariant failed: found ", used, " used slots, but used count is ", t.used, "\n")
t.Print(typ)
t.Print(typ, m)
panic("invariant failed: found mismatched used slot count")
}
growthLeft := (t.capacity*maxAvgGroupLoad)/abi.SwissMapGroupSlots - t.used - deleted
if growthLeft != t.growthLeft {
print("invariant failed: found ", t.growthLeft, " growthLeft, but expected ", growthLeft, "\n")
t.Print(typ)
t.Print(typ, m)
panic("invariant failed: found mismatched growthLeft")
}
if deleted != t.tombstones() {
print("invariant failed: found ", deleted, " tombstones, but expected ", t.tombstones(), "\n")
t.Print(typ)
t.Print(typ, m)
panic("invariant failed: found mismatched tombstones")
}
if empty == 0 {
print("invariant failed: found no empty slots (violates probe invariant)\n")
t.Print(typ)
t.Print(typ, m)
panic("invariant failed: found no empty slots (violates probe invariant)")
}
}
func (t *table) Print(typ *abi.SwissMapType) {
func (t *table) Print(typ *abi.SwissMapType, m *Map) {
print(`table{
seed: `, t.seed, `
index: `, t.index, `
localDepth: `, t.localDepth, `
capacity: `, t.capacity, `