cvs commit: src/sys/kern kern_kse.c

[David Xu]

davidxu     2004-07-13 07:33:40 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             kern_kse.c 
  Log:
  Add code to support debugging threaded process.
  
    1. Add tm_lwpid into kse_thr_mailbox to indicate which kernel
       thread current user thread is running on. Add tm_dflags into
       kse_thr_mailbox, the flags is written by debugger, it tells
       UTS and kernel what should be done when the process is being
       debugged, current, there two flags TMDF_SSTEP and TMDF_DONOTRUNUSER.
  
       TMDF_SSTEP is used to tell kernel to turn on single stepping,
       or turn off if it is not set.
  
       TMDF_DONOTRUNUSER is used to tell kernel to schedule upcall
       whenever possible, to UTS, it means do not run the user thread
       until debugger clears it, this behaviour is necessary because
       gdb wants to resume only one thread when the thread's pc is
       at a breakpoint, and thread needs to go forward, in order to
       avoid other threads sneak pass the breakpoints, it needs to remove
       breakpoint, only wants one thread to go. Also, add km_lwp to
       kse_mailbox, the lwp id is copied to kse_thr_mailbox at context
       switch time when process is not being debugged, so when process
       is attached, debugger can map kernel thread to user thread.
  
    2. Add p_xthread to proc strcuture and td_xsig to thread structure.
       p_xthread is used by a thread when it wants to report event
       to debugger, every thread can set the pointer, especially, when
       it is used in ptracestop, it is the last thread reporting event
       will win the race. Every thread has a td_xsig to exchange signal
       with debugger, thread uses TDF_XSIG flag to indicate it is reporting
       signal to debugger, if the flag is not cleared, thread will keep
       retrying until it is cleared by debugger, p_xthread may be
       used by debugger to indicate CURRENT thread. The p_xstat is still
       in proc structure to keep wait() to work, in future, we may
       just use td_xsig.
  
    3. Add TDF_DBSUSPEND flag, the flag is used by debugger to suspend
       a thread. When process stops, debugger can set the flag for
       thread, thread will check the flag in thread_suspend_check,
       enters a loop, unless it is cleared by debugger, process is
       detached or process is existing. The flag is also checked in
       ptracestop, so debugger can temporarily suspend a thread even
       if the thread wants to exchange signal.
  
    4. Current, in ptrace, we always resume all threads, but if a thread
       has already a TDF_DBSUSPEND flag set by debugger, it won't run.
  
  Encouraged by: marcel, julian, deischen
  
  Revision  Changes    Path
  1.184     +153 -75   src/sys/kern/kern_kse.c