Re: [PATCH v2] MIPS/bpf: Enable bpf_probe_read{, str}() on MIPS again

From: Maciej W. Rozycki
Date: Sun Mar 28 2021 - 17:07:27 EST


On Thu, 25 Mar 2021, Tiezhu Yang wrote:

> > > I wonder whether MIPS EVA will generate overlapping address ranges?
> > they can overlap in EVA mode.
> >
> > > If yes, it is better to make ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE depend
> > > on !EVA on MIPS.
> > Could please add the change ?
>
> OK, thank you, I will do it soon.

For the record this is clearly described and accompanied with a drawing
[1][2] in the architecture specification. I do encourage you and anyone
serious about contributing to the MIPS/Linux project to make yourselves
familiar with the architecture beyond the area of your immediate interest
so as to offload the maintainers who are often overloaded and sometimes do
their work in their precious free time. There are so many contributors
and so few maintainers, so please help everyone and spread the work.

Also please pay attention to quality change descriptions. It's your task
to convince the maintainer your work is worth including, and in your best
interest to make the decision easy to make for the maintainer. Think in
terms of an exam at the university and what you would do to persuade your
professor to give you a good score. This is what the change description
is for, beyond the quality of the change itself of course.

This general rule of course applies to any community-maintained projects
and not only MIPS/Linux.

References:

[1] "MIPS Architecture For Programmers, Vol. III: MIPS32/microMIPS32
Privileged Resource Architecture", Document Number: MD00090, Revision
5.05, November 14, 2014, Figure 4.5 "EVA addressability", p. 51,
<https://wavecomp.ai/mips-technology/>

[2] "MIPS Architecture For Programmers, Volume III: The MIPS64 and
microMIPS64 Privileged Resource Architecture", Document Number:
MD00091, Revision 5.04, January 15, 2014, Figure 4.5 "EVA
addressability", p. 58, <https://wavecomp.ai/mips-technology/>

Maciej