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

Assisted-by: GLM 5.3

debug/stopinfo_linux.go

@@ -6,6 +6,7 @@
 package debug
 
 import (
+	"encoding/binary"
 	"syscall"
 	"unsafe"
 )
@@ -61,8 +62,15 @@ func (s *Session) StopInfo() (StopReason, uint64) {
 	case trapBRKPT:
 		return StopBreakpoint, 0
 	case trapHWBRKPT:
-		addr := *(*uint64)(unsafe.Add(unsafe.Pointer(&info), 16))
-		return StopWatchpoint, addr
+		// si_addr sits at struct offset 16 (12 bytes of signo/errno/code
+		// plus 4 bytes of union alignment).  The siginfo buffer is only
+		// 4-byte aligned, so the address is read byte-wise to keep the
+		// load aligned on riscv64 and loong64.  What si_addr names is
+		// architecture-specific (the data address on arm64, the
+		// instruction pointer on x86), so the per-architecture
+		// archWatchpointAddr resolves it to the watched address.
+		addr := binary.LittleEndian.Uint64(info._pad[4:12])
+		return StopWatchpoint, archWatchpointAddr(s, addr)
 	default:
 		return StopSingleStep, 0
 	}