m68k version of Eric's 'improved switch stack handling' patch for alpha. The first two patches address m68k missing saving switch_stack on those syscalls that can may call ptrace_stop(), and adding a full stack frame in kernel threads. The last patch adds a 'status' field to m68k thread_info struct, and stores information about whether a syscall trace is in progress, and a full stack frame has been saved, in that field. This information can be used in arch/m68k/kernel/ptrace.c by get/put_reg() to guard against accessing incorrect information on the stack (haven't got around to that bit yet). I'm quite certain I haven't picked the most efficient implementation here - suggestions to optimize most welcome! Cheers, Michael
