• Soeren Sandmann Pedersen's avatar
    x86: Eliminate bp argument from the stack tracing routines · 9c0729dc
    Soeren Sandmann Pedersen authored
    The various stack tracing routines take a 'bp' argument in which the
    caller is supposed to provide the base pointer to use, or 0 if doesn't
    have one. Since bp is garbage whenever CONFIG_FRAME_POINTER is not
    defined, this means all callers in principle should either always pass
    0, or be conditional on CONFIG_FRAME_POINTER.
    
    However, there are only really three use cases for stack tracing:
    
    (a) Trace the current task, including IRQ stack if any
    (b) Trace the current task, but skip IRQ stack
    (c) Trace some other task
    
    In all cases, if CONFIG_FRAME_POINTER is not defined, bp should just
    be 0.  If it _is_ defined, then
    
    - in case (a) bp should be gotten directly from the CPU's register, so
      the caller should pass NULL for regs,
    
    - in case (b) the caller should should pass the IRQ registers to
      dump_trace(),
    
    - in case (c) bp should be gotten from the top of the task's stack, so
      the caller should pass NULL for regs.
    
    Hence, the bp argument is not necessary because the combination of
    task and regs is sufficient to determine an appropriate value for bp.
    
    This patch introduces a new inline function stack_frame(task, regs)
    that computes the desired bp. This function is then called from the
    two versions of dump_stack().
    Signed-off-by: default avatarSoren Sandmann <ssp@redhat.com>
    Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Arjan van de Ven <arjan@infradead.org>,
    Cc: Frederic Weisbecker <fweisbec@gmail.com>,
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>,
    LKML-Reference: <m3oc9rop28.fsf@dhcp-100-3-82.bos.redhat.com>>
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    9c0729dc
dumpstack_64.c 8.2 KB