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    SubjectRe: [PATCH v3 39/51] x86/dumpstack: convert show_trace_log_lvl() to use the new unwinder
    On Sun, Aug 14, 2016 at 01:13:54AM -0700, Andy Lutomirski wrote:
    > On Fri, Aug 12, 2016 at 7:28 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
    > > Convert show_trace_log_lvl() to use the new unwinder. dump_trace() has
    > > been deprecated.
    >
    > >
    > > Another change here is that callers of show_trace_log_lvl() don't need
    > > to provide the 'bp' argument. The unwinder already finds the relevant
    > > frame pointer by unwinding until it reaches the first frame after the
    > > provided stack pointer.
    >
    > I still think that the best long-term solution is to change the sp and
    > bp arguments to an optional state argument and to add a helper to
    > capture the current state for future unwinding, but this is okay too.
    > (If nothing else, this may improve DWARF's ability to recover function
    > arguments and such that are available when the trace is requested but
    > that are gone by the time the unwinder runs. But mainly because it
    > seems simpler and more direct to me and therefore seems like it will
    > be less likely to get confused and skip too many frames.)
    >
    > But I'm okay with this for now.

    Long term, maybe something like an unwind_capture_state() helper might
    be best (though I'm not yet convinced either way). However it wouldn't
    quite work with today's code because show_stack(), which is implemented
    for all architectures, takes 'sp' as an argument.

    --
    Josh

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