+ if (regnum >= num_regs)
+ return -1;
+
+ /* Kernels that predate Linux 2.6.25 don't provide access to
+ these segment registers in user_regs_struct. */
+#ifndef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE
+ if (regnum == AMD64_FSBASE_REGNUM || regnum == AMD64_GSBASE_REGNUM)
+ return -1;
+#endif