Re: [PATCH v2] perf probe: Fix add event failed when 32-bit perf running in 64-bit kernel

[Yang Jihong]

Hello Hiramatsu,

On 2021/7/15 17:05, Masami Hiramatsu wrote:
> On Thu, 15 Jul 2021 14:37:23 +0800
> Yang Jihong <yangjihong1@xxxxxxxxxx> wrote:
>
> > The "address" member  of "struct probe_trace_point" uses long data type.
> > If kernel is 64-bit and perf program is 32-bit, size of "address" variable is
> > 32 bits. As a result, upper 32 bits of address read from kernel are truncated,
> > An error occurs during address comparison in kprobe_warn_out_range function.
> >
> > Before:
> >
> >    # perf probe -a schedule
> >    schedule is out of .text, skip it.
> >      Error: Failed to add events.
> >
> > Solution:
> >    Change data type of "address" variable to u64 and change corresponding
> > address printing and value assignment.
> >
> > After:
> >
> >    # perf.new.new probe -a schedule
> >    Added new event:
> >      probe:schedule       (on schedule)
> >
> >    You can now use it in all perf tools, such as:
> >
> >            perf record -e probe:schedule -aR sleep 1
> >
> >    # perf probe -l
> >      probe:schedule       (on schedule@kernel/sched/core.c)
> >    # perf record -e probe:schedule -aR sleep 1
> >    [ perf record: Woken up 1 times to write data ]
> >    [ perf record: Captured and wrote 0.156 MB perf.data (1366 samples) ]
> >    # perf report --stdio
> >    # To display the perf.data header info, please use --header/--header-only options.
> >    #
> >    #
> >    # Total Lost Samples: 0
> >    #
> >    # Samples: 1K of event 'probe:schedule'
> >    # Event count (approx.): 1366
> >    #
> >    # Overhead  Command          Shared Object      Symbol
> >    # ........  ...............  .................  ............
> >    #
> >         6.22%  migration/0      [kernel.kallsyms]  [k] schedule
> >         6.22%  migration/1      [kernel.kallsyms]  [k] schedule
> >         6.22%  migration/2      [kernel.kallsyms]  [k] schedule
> >         6.22%  migration/3      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/10     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/11     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/12     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/13     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/14     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/15     [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/4      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/5      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/6      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/7      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/8      [kernel.kallsyms]  [k] schedule
> >         6.15%  migration/9      [kernel.kallsyms]  [k] schedule
> >         0.22%  rcu_sched        [kernel.kallsyms]  [k] schedule
> >    ...
> >    #
> >    # (Cannot load tips.txt file, please install perf!)
> >    #
>
> OK, this looks good to me :)
>
> Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thanks for the Acked :)

Jihong