Re: [PATCH 1/3] RISC-V: add Bitmanip/Scalar Crypto parsing from DT

[Evan Green]

On Wed, Jun 28, 2023 at 4:10 AM Conor Dooley <conor.dooley@xxxxxxxxxxxxx> wrote:
>
> On Wed, Jun 28, 2023 at 12:01:11PM +0200, Samuel Ortiz wrote:
> > On Tue, Jun 27, 2023 at 07:48:15PM +0100, Conor Dooley wrote:
> > > On Tue, Jun 27, 2023 at 11:14:30AM -0700, Evan Green wrote:
> > > > On Tue, Jun 27, 2023 at 7:38 AM Samuel Ortiz <sameo@xxxxxxxxxxxx> wrote:
>
> > > > It would be nice to consolidate the ones together that search for a
> > > > single string and set multiple bits, though I don't have any super
> > > > elegant ideas for how off the top of my head.
> > >
> > > I've got a refactor of this code in progress, dropping all of these
> > > copy-paste in place of a loop. It certainly looks more elegant than
> > > this, but it will fall over a bit for these "one string matches many
> > > extensions" cases. See here:
> > > https://patchwork.kernel.org/project/linux-riscv/patch/20230626-thieving-jockstrap-d35d20b535c5@wendy/
> > > My immediate thought is to add another element to riscv_isa_ext_data,
> > > that contains "parent" extensions to check for. Should be fairly doable,
> > > I'll whip something up on top of that...
> >
> > Nice, and thanks for the review.
>
> > Should I wait for your refactor to be merged before pushing this one?
>
> I don't know. I think that you should continue on with your series here,
> and whichever goes in second gets rebased on top of the other.
> I don't think it makes material difference to review of this patchset as
> to whether you rebase on top of what I'm working on, so I wouldn't
> bother until it gets merged.
>
> Rather hacky, had less time than expected this morning:
> https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/commit/?h=riscv-extensions-strings-supersets
> Clearly there's issues with looping to RISCV_ISA_MAX_SUPERSETS & I just
> repurposed Zicsr for the sake of testing something in the time I had.
>
> Evan, at a high level, does that look more elegant to you, or have I made
> things worse?
>

I see what you're going for at least. It's unfortunate that when
someone bumps up RISCV_ISA_MAX_SUPERSETS it squares the whole array.
Another way to go might be to define the elements in a separate array,
like:

unsigned int riscv_zks_exts[] = {
       RISCV_ISA_EXT_ZBKB,
       RISCV_ISA_EXT_ZBKC,
       ....
};

then the macro entry looks like:

SET_ISA_EXT_MAP_MULTI("zks", riscv_zks_exts),

where the SET_ISA_EXT_MAP_MULTI() could use ARRAY_SIZE() to stash both
the pointer to the array and the number of elements.

-Evan