Re: [PATCH 1/2] scripts: ftrace - move the sort-processing in ftrace_init to compile time

[Yinan Liu]

On 2021/10/9 上午7:48, Steven Rostedt wrote:
> On Sun, 3 Oct 2021 21:42:10 +0800
> Yinan Liu <yinan@xxxxxxxxxxxxxxxxx> wrote:
>
> > Sorry for my slow progress . I have encountered some problems with the
> > sorting
> > of the module's mcount in compile time. The .ko file will be relocated
> > after insmod
> > or modprobe, most of the mcount relocation is based on .text section,
> > but there are
> > also a small part of mcount relocation based on .init.text section such
> > as module_init().
> > The loading position of .init.text and .text does not seem to be in a
> > definite order.
>
> Right, there's no guarantee that the .text portion of a module is
> placed before or after the .init.text portion.
yes.
> > For example, when I insmod ip_tables.ko twice, the front and back
> > positions of init.text
> > and .text are different, so we cannot sort the mcounts in the two
> > sections, which makes
> > the mcount sorting in the module meaningless.
> >
> > What is your opinion on this?
>
> Probably just keep the sorting algorithm in the kernel and take place
> on module load.
>
> If you still want to sort at compile time, then do the sort for .init
> functions separate from the .text ones, and have a way to extract this
> information (shouldn't be too hard) in the kernel at module load, and
> then just swap the init and text functions if they were added in the
> reverse order that was expect.
>
> The functions in .init will either be before all the functions in .text
> or after. They wont be intermingled. Thus, if they are both sorted,
> then they are placed correctly or the two groups of functions need to
> be switched. No other sorting should be necessary.
Thanks so much! I see. And I will have a try.
> -- Steve
Best regards!
-- Yinan liu