1. 28 Mar, 2008 1 commit
    • Michael Ellerman's avatar
      [POWERPC] Fix missed hardware breakpoints across multiple threads · a2ceff5e
      Michael Ellerman authored
      There is a bug in the powerpc DABR (data access breakpoint) handling,
      which can result in us missing breakpoints if several threads are trying
      to break on the same address.
      
      The circumstances are that do_page_fault() calls do_dabr(), this clears
      the DABR (sets it to 0) and sets up the signal which will report to
      userspace that the DABR was hit. The do_signal() code will restore the DABR
      value on the way out to userspace.
      
      If we reschedule before calling do_signal(), __switch_to() will check the
      cached DABR value and compare it to the new thread's value, if they match
      we don't set the DABR in hardware.
      
      So if two threads have the same DABR value, and we schedule from one to
      the other after taking the interrupt for the first thread hitting the DABR,
      the second thread will run without the DABR set in hardware.
      
      The cleanest fix is to move the cache update into set_dabr(), that way we
      can't forget to do it.
      Reported-by: default avatarJan Kratochvil <jan.kratochvil@redhat.com>
      Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
      Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
      a2ceff5e
  2. 25 Mar, 2008 3 commits
  3. 24 Mar, 2008 17 commits
  4. 23 Mar, 2008 13 commits
  5. 22 Mar, 2008 6 commits