1. 17 10月, 2007 5 次提交
  2. 20 9月, 2007 1 次提交
    • J
      uml: fix irqstack crash · 508a9274
      Jeff Dike 提交于
      This patch fixes a crash caused by an interrupt coming in when an IRQ stack
      is being torn down.  When this happens, handle_signal will loop, setting up
      the IRQ stack again because the tearing down had finished, and handling
      whatever signals had come in.
      
      However, to_irq_stack returns a mask of pending signals to be handled, plus
      bit zero is set if the IRQ stack was already active, and thus shouldn't be
      torn down.  This causes a problem because when handle_signal goes around
      the loop, sig will be zero, and to_irq_stack will duly set bit zero in the
      returned mask, faking handle_signal into believing that it shouldn't tear
      down the IRQ stack and return thread_info pointers back to their original
      values.
      
      This will eventually cause a crash, as the IRQ stack thread_info will
      continue pointing to the original task_struct and an interrupt will look
      into it after it has been freed.
      
      The fix is to stop passing a signal number into to_irq_stack.  Rather, the
      pending signals mask is initialized beforehand with the bit for sig already
      set.  References to sig in to_irq_stack can be replaced with references to
      the mask.
      
      [akpm@linux-foundation.org: use UL]
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      508a9274
  3. 17 7月, 2007 5 次提交
  4. 17 6月, 2007 1 次提交
  5. 16 5月, 2007 1 次提交
  6. 11 5月, 2007 2 次提交
    • J
      uml: iRQ stacks · c14b8494
      Jeff Dike 提交于
      Add a separate IRQ stack.  This differs from i386 in having the entire
      interrupt run on a separate stack rather than starting on the normal kernel
      stack and switching over once some preparation has been done.  The underlying
      mechanism, is of course, sigaltstack.
      
      Another difference is that interrupts that happen in userspace are handled on
      the normal kernel stack.  These cause a wait wakeup instead of a signal
      delivery so there is no point in trying to switch stacks for these.  There's
      no other stuff on the stack, so there is no extra stack consumption.
      
      This quirk makes it possible to have the entire interrupt run on a separate
      stack - process preemption (and calls to schedule()) happens on a normal
      kernel stack.  If we enable CONFIG_PREEMPT, this will need to be rethought.
      
      The IRQ stack for CPU 0 is declared in the same way as the initial kernel
      stack.  IRQ stacks for other CPUs will be allocated dynamically.
      
      An extra field was added to the thread_info structure.  When the active
      thread_info is copied to the IRQ stack, the real_thread field points back to
      the original stack.  This makes it easy to tell where to copy the thread_info
      struct back to when the interrupt is finished.  It also serves as a marker of
      a nested interrupt.  It is NULL for the first interrupt on the stack, and
      non-NULL for any nested interrupts.
      
      Care is taken to behave correctly if a second interrupt comes in when the
      thread_info structure is being set up or taken down.  I could just disable
      interrupts here, but I don't feel like giving up any of the performance gained
      by not flipping signals on and off.
      
      If an interrupt comes in during these critical periods, the handler can't run
      because it has no idea what shape the stack is in.  So, it sets a bit for its
      signal in a global mask and returns.  The outer handler will deal with this
      signal itself.
      
      Atomicity is had with xchg.  A nested interrupt that needs to bail out will
      xchg its signal mask into pending_mask and repeat in case yet another
      interrupt hit at the same time, until the mask stabilizes.
      
      The outermost interrupt will set up the thread_info and xchg a zero into
      pending_mask when it is done.  At this point, nested interrupts will look at
      ->real_thread and see that no setup needs to be done.  They can just continue
      normally.
      
      Similar care needs to be taken when exiting the outer handler.  If another
      interrupt comes in while it is copying the thread_info, it will drop a bit
      into pending_mask.  The outer handler will check this and if it is non-zero,
      will loop, set up the stack again, and handle the interrupt.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c14b8494
    • J
      uml: remove task_protections · 57598fd7
      Jeff Dike 提交于
      Replaced task_protections with stack_protections since they do the same
      thing, and task_protections was misnamed anyway.
      
      This needs THREAD_SIZE, so that's imported via common-offsets.h
      
      Also tidied up the code in the vicinity.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      57598fd7
  7. 09 5月, 2007 1 次提交
  8. 08 5月, 2007 20 次提交
  9. 29 3月, 2007 1 次提交
  10. 28 3月, 2007 1 次提交
    • J
      [PATCH] uml: use correct register file size everywhere · b92c4f92
      Jeff Dike 提交于
      This patch uses MAX_REG_NR consistently to refer to the register file size.
       FRAME_SIZE isn't sufficient because on x86_64, it is smaller than the
      ptrace register file size.  MAX_REG_NR was introduced as a consistent way
      to get the number of registers, but wasn't used everywhere it should be.
      
      When this causes a problem, it makes PTRACE_SETREGS fail on x86_64 because
      of a corrupted segment register value in the known-good register file.  The
      patch also adds a register dump at that point in case there are any future
      problems here.
      Signed-off-by: NJeff Dike <jdike@linux.intel.com>
      Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
      Cc: <stable@kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b92c4f92
  11. 08 3月, 2007 1 次提交
  12. 13 2月, 2007 1 次提交