linux-kernel - Re: [PATCH V2] perf scripts python arm-cs-trace-disasm.py: Skip disasm of discontiguous packets

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Message-ID: <607b4abd-108c-4d3c-97e4-906a0a21aab5@arm.com>
Date: Fri, 9 Aug 2024 15:06:08 +0100
From: Leo Yan <leo.yan@....com>
To: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
 james.clark@....com, mike.leach@...aro.org, suzuki.poulose@....com
Cc: acme@...hat.com, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, darren@...amperecomputing.com,
 scclevenger@...amperecomputing.com
Subject: Re: [PATCH V2] perf scripts python arm-cs-trace-disasm.py: Skip
 disasm of discontiguous packets

On 8/9/24 10:40, Ganapatrao Kulkarni wrote:> Script uses contiguous address range of adjacent packets to generate
> the tracing. When there is a continuity brake due to discontiguous
> branch address, it is resulting in to a perf tool crash(segfault).
> This is expected bhehaviour since the decoder is not expecting the
> discontiguous packets.
> 
> Adding an option "force" to allow the decoder to continue and complete
> the tracing without application crash by dropping the discontiguous
> packets from decoding.
> 
> Signed-off-by: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
> ---
> 
> Changes since V1:
>          Updated patch as per discussions[1].
> 
> [1] https://lore.kernel.org/linux-arm-kernel/ce4af204-874f-404c-a7aa-42dc6693d072@linaro.org/T/
> 
>   tools/perf/scripts/python/arm-cs-trace-disasm.py | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/scripts/python/arm-cs-trace-disasm.py b/tools/perf/scripts/python/arm-cs-trace-disasm.py
> index d973c2baed1c..65d59db3bcec 100755
> --- a/tools/perf/scripts/python/arm-cs-trace-disasm.py
> +++ b/tools/perf/scripts/python/arm-cs-trace-disasm.py
> @@ -36,7 +36,10 @@ option_list = [
>                      help="Set path to objdump executable file"),
>          make_option("-v", "--verbose", dest="verbose",
>                      action="store_true", default=False,
> -                   help="Enable debugging log")
> +                   help="Enable debugging log"),
> +       make_option("-f", "--force", dest="force",
> +                   action="store_true", default=False,
> +                   help="Force decoder to continue")
>   ]
> 
>   parser = OptionParser(option_list=option_list)
> @@ -257,6 +260,13 @@ def process_event(param_dict):
>                  print("Stop address 0x%x is out of range [ 0x%x .. 0x%x ] for dso %s" % (stop_addr, int(dso_start), int(dso_end), dso))
>                  return
> 
> +       if (stop_addr < start_addr):
> +               if (options.verbose or not options.force):
> +                       print("Packet Discontinuity detected [stop_add:0x%x start_addr:0x%x ] for dso %s" % (stop_addr, start_addr, dso))
> +                       print("Use option '-f' following the script for force mode")
> +               if (options.force):
> +                               return

A redundant indentation? After fix it:

Reviewed-by: Leo Yan <leo.yan@....com>
  
> +
>          if (options.objdump_name != None):
>                  # It doesn't need to decrease virtual memory offset for disassembly
>                  # for kernel dso and executable file dso, so in this case we set
> --
> 2.44.0
>