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fix(debug): hardware watchpoints, signal stops and breakpoint restore

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Assisted-by: GLM 5.3
This commit is contained in:
petrbalvin
2026-09-19 23:49:19 +02:00
parent 375182ef1f
commit a8bfd54ed2
26 changed files with 1408 additions and 535 deletions
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debug/watchpoint_linux_arm64.go
+41 -28
View File
@@ -12,7 +12,7 @@ import (
)
// Hardware watchpoint support via arm64 debug registers (DBGWVR/DBGWCR).
// Accessed via PTRACE_SETREGSET with NT_ARM_HW_BREAK.
// Accessed via PTRACE_GETREGSET/SETREGSET with NT_ARM_HW_WATCH.
// WatchpointType selects what triggers the watchpoint.
type WatchpointType int
@@ -22,26 +22,35 @@ const (
WatchRead WatchpointType = 3
)
const maxWatchpoints = 16
// maxWatchpoints reports the number of hardware watchpoint slots the
// architecture provides: DBGWVR0-DBGWCR15.
func maxWatchpoints() int { return 16 }
// hwBreakState mirrors the kernel's struct user_hwdebug_state.
type hwBreakState struct {
// hwWatchState mirrors the kernel's struct user_hwdebug_state.
type hwWatchState struct {
DbgInfo uint32
_pad [4]byte
DbgRegs [16]hwBreakReg
DbgRegs [16]hwWatchReg
}
type hwBreakReg struct {
type hwWatchReg struct {
Addr uint64
Ctrl uint64
}
const (
ntArmHWBreak = 0x403 // NT_ARM_HW_BREAK
)
// ntArmHWWatch is NT_ARM_HW_WATCH (0x403), the watchpoint regset
// (include/uapi/linux/elf.h; 0x402 is NT_ARM_HW_BREAK). Watchpoints and
// breakpoints live in different regsets with the same struct shape, so the
// constant is named for what it arms to keep a future edit from arming
// breakpoints instead.
const ntArmHWWatch = 0x403
// archWatchpointAddr resolves the address of the watchpoint that fired:
// the arm64 kernel already reports the watched data address as si_addr.
func archWatchpointAddr(s *Session, siAddr uint64) uint64 { return siAddr }
func (s *Session) FindFreeWatchpointSlot() int {
for i := range maxWatchpoints {
for i := range maxWatchpoints() {
if !s.wpSlots[i] {
return i
}
@@ -50,7 +59,7 @@ func (s *Session) FindFreeWatchpointSlot() int {
}
func (s *Session) IsWatchpointSlotUsed(slot int) bool {
if slot < 0 || slot >= maxWatchpoints {
if slot < 0 || slot >= maxWatchpoints() {
return false
}
return s.wpSlots[slot]
@@ -58,27 +67,31 @@ func (s *Session) IsWatchpointSlotUsed(slot int) bool {
// SetWatchpoint installs a hardware watchpoint on the given address.
func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size int) error {
if slot < 0 || slot >= maxWatchpoints {
return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
if slot < 0 || slot >= maxWatchpoints() {
return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints()-1)
}
if s.wpSlots[slot] {
return fmt.Errorf("debug: watchpoint slot %d already in use", slot)
}
state, err := s.getHWBreakState()
state, err := s.getHWWatchState()
if err != nil {
return fmt.Errorf("debug: read watchpoint state: %w", err)
}
if uint32(slot) >= state.DbgInfo {
return fmt.Errorf("debug: slot %d exceeds available watchpoints (%d)", slot, state.DbgInfo)
// MDSCR_EL1 packs (debug_arch << 8) | num_slots into dbg_info, so only
// the low byte counts slots.
if uint32(slot) >= state.DbgInfo&0xff {
return fmt.Errorf("debug: slot %d exceeds available watchpoints (%d)", slot, state.DbgInfo&0xff)
}
state.DbgRegs[slot].Addr = addr
// DBGWCR bits 3-4 select the access type: 01 load, 10 store, 11 either
// (ARM DDI 0487, DBGWCR<n>_EL1 watchpoint type field).
ctrl := uint64(1) // enable
switch typ {
case WatchWrite:
ctrl |= 1 << 3 // store only
ctrl |= 2 << 3 // store only
case WatchRead:
ctrl |= 3 << 3 // load+store
}
@@ -98,7 +111,7 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
ctrl |= bas << 5
state.DbgRegs[slot].Ctrl = ctrl
if err := s.setHWBreakState(state); err != nil {
if err := s.setHWWatchState(state); err != nil {
return fmt.Errorf("debug: set watchpoint: %w", err)
}
@@ -107,20 +120,20 @@ func (s *Session) SetWatchpoint(slot int, addr uint64, typ WatchpointType, size
}
func (s *Session) ClearWatchpoint(slot int) error {
if slot < 0 || slot >= maxWatchpoints {
return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints-1)
if slot < 0 || slot >= maxWatchpoints() {
return fmt.Errorf("debug: watchpoint slot must be 0-%d", maxWatchpoints()-1)
}
if !s.wpSlots[slot] {
return fmt.Errorf("debug: watchpoint slot %d is not in use", slot)
}
state, err := s.getHWBreakState()
state, err := s.getHWWatchState()
if err != nil {
return err
}
state.DbgRegs[slot].Addr = 0
state.DbgRegs[slot].Ctrl = 0
if err := s.setHWBreakState(state); err != nil {
if err := s.setHWWatchState(state); err != nil {
return err
}
s.wpSlots[slot] = false
@@ -128,7 +141,7 @@ func (s *Session) ClearWatchpoint(slot int) error {
}
func (s *Session) ClearAllWatchpoints() error {
for slot := 0; slot < maxWatchpoints; slot++ {
for slot := range maxWatchpoints() {
if s.wpSlots[slot] {
if err := s.ClearWatchpoint(slot); err != nil {
return err
@@ -138,8 +151,8 @@ func (s *Session) ClearAllWatchpoints() error {
return nil
}
func (s *Session) getHWBreakState() (*hwBreakState, error) {
var state hwBreakState
func (s *Session) getHWWatchState() (*hwWatchState, error) {
var state hwWatchState
iovec := syscall.Iovec{
Base: (*byte)(unsafe.Pointer(&state)),
Len: uint64(unsafe.Sizeof(state)),
@@ -148,7 +161,7 @@ func (s *Session) getHWBreakState() (*hwBreakState, error) {
syscall.SYS_PTRACE,
uintptr(syscall.PTRACE_GETREGSET),
uintptr(s.pid),
uintptr(ntArmHWBreak),
uintptr(ntArmHWWatch),
uintptr(unsafe.Pointer(&iovec)),
0, 0,
)
@@ -158,7 +171,7 @@ func (s *Session) getHWBreakState() (*hwBreakState, error) {
return &state, nil
}
func (s *Session) setHWBreakState(state *hwBreakState) error {
func (s *Session) setHWWatchState(state *hwWatchState) error {
iovec := syscall.Iovec{
Base: (*byte)(unsafe.Pointer(state)),
Len: uint64(unsafe.Sizeof(*state)),
@@ -167,7 +180,7 @@ func (s *Session) setHWBreakState(state *hwBreakState) error {
syscall.SYS_PTRACE,
uintptr(syscall.PTRACE_SETREGSET),
uintptr(s.pid),
uintptr(ntArmHWBreak),
uintptr(ntArmHWWatch),
uintptr(unsafe.Pointer(&iovec)),
0, 0,
)