fix(debug): cross-compile for arm64, riscv64 and loong64

Assisted-by: GLM 5.3 Flash

debug/ptrace_linux_riscv64.go

@@ -44,25 +44,34 @@ func (s *Session) SetRegs(regs *Regs) error {
 	return nil
 }
 
-// FPRegs holds the RISC-V FP register state (F0-F31).
+// ntPrFPREG is the NT_PRFPREG note type (ELF NT ver): the FP register set.
+const ntPrFPREG = 0x2
+
+// FPRegs holds the RISC-V FP register state, matching the kernel's
+// user_fp_struct layout (32 64-bit FP registers plus fcsr).
 type FPRegs struct {
-	F    [32][16]byte // F0-F31 (128-bit, lower 64 bits used for double)
+	F    [32]uint64 // F0-F31 (64-bit FP registers)
 	FCSR uint32
 }
 
-// GetFPRegs retrieves the FP register state.
+// GetFPRegs retrieves the FP register state via PTRACE_GETREGSET with
+// NT_PRFPREG (this architecture has no PTRACE_GETFPREGS request).
 func (s *Session) GetFPRegs() (FPRegs, error) {
 	var fp FPRegs
+	iovec := syscall.Iovec{
+		Base: (*byte)(unsafe.Pointer(&fp)),
+		Len:  uint64(unsafe.Sizeof(fp)),
+	}
 	_, _, errno := syscall.Syscall6(
 		syscall.SYS_PTRACE,
-		uintptr(syscall.PTRACE_GETFPREGS),
+		uintptr(syscall.PTRACE_GETREGSET),
 		uintptr(s.pid),
-		0,
-		uintptr(unsafe.Pointer(&fp)),
+		uintptr(ntPrFPREG),
+		uintptr(unsafe.Pointer(&iovec)),
 		0, 0,
 	)
 	if errno != 0 {
-		return fp, fmt.Errorf("debug: PTRACE_GETFPREGS: %w", errno)
+		return fp, fmt.Errorf("debug: PTRACE_GETREGSET (NT_PRFPREG): %w", errno)
 	}
 	return fp, nil
 }