[Crash-utility] Re: [RFC] Crash patch for DWARF CFI based unwind support

[Dave Anderson]

Rachita Kothiyal wrote:

> Hi Dave
>
> The following patch adds support for DWARF CFI based stack unwinding
> for crash. Since this method uses the call frame instructions for
> unwinding, it generates better backtraces than the existing backtrace
> mechanism. So when we have the unwind info available, this new method
> will be called, else we fall back to the existing mechanism.
>
> There still are a couple of things which need to be done, viz
> 1. Extend to obtaining unwind info from modules as well(currently
>    doing only for the kernel)
> 2. Currently reading the unwind info from eh_frame section only(ie
>    __start_unwind to __end_unwind). Need to add facility to read from
>    the .debug_frame(if .debug_frame is present in cases where .eh_frame
>    is absent. Will have to read from the vmlinux if we want to read the
>    .debug_frame info)
> 3. Add FRAME_POINTER support.
>
> Please provide your suggestions and comments.
>
> Thanks
> Rachita

Hi Rachita,

Thanks very much -- I've been looking forward to this.

I'll apply and work with the patch today, and respond as
soon as I can.  Upon a quick investigation, this looks to
be an excellent incremental starting point that we can
build upon as we go.

Thanks again,
  Dave