linux-kernel - Re: [PATCH] riscv: hwprobe: export Zicntr and Zihpm extensions

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Message-ID: <20240819-unclamped-cheek-9b4851bed13f@spud>
Date: Mon, 19 Aug 2024 18:34:09 +0100
From: Conor Dooley <conor@...nel.org>
To: Jesse Taube <jesse@...osinc.com>
Cc: Miquel Sabaté Solà <mikisabate@...il.com>,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: hwprobe: export Zicntr and Zihpm extensions

On Mon, Aug 19, 2024 at 01:29:16PM -0400, Jesse Taube wrote:
> On Sat, Aug 17, 2024 at 3:58 AM Miquel Sabaté Solà <mikisabate@...il.com> wrote:
> >
> > Export Zicntr and Zihpm ISA extensions through the hwprobe syscall.
> >
> > Signed-off-by: Miquel Sabaté Solà <mikisabate@...il.com>
> > ---
> >  Documentation/arch/riscv/hwprobe.rst  | 6 ++++++
> >  arch/riscv/include/uapi/asm/hwprobe.h | 2 ++
> >  arch/riscv/kernel/sys_hwprobe.c       | 2 ++
> >  3 files changed, 10 insertions(+)
> >
> > diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
> > index 3db60a0911df..5bb69c985cce 100644
> > --- a/Documentation/arch/riscv/hwprobe.rst
> > +++ b/Documentation/arch/riscv/hwprobe.rst
> > @@ -188,10 +188,16 @@ The following keys are defined:
> >         manual starting from commit 95cf1f9 ("Add changes requested by Ved
> >         during signoff")
> >
> > +  * :c:macro:`RISCV_HWPROBE_EXT_ZICNTR`: The Zicntr extension version 2.0
> > +       is supported as defined in the RISC-V ISA manual.
> > +
> >    * :c:macro:`RISCV_HWPROBE_EXT_ZIHINTPAUSE`: The Zihintpause extension is
> >         supported as defined in the RISC-V ISA manual starting from commit
> >         d8ab5c78c207 ("Zihintpause is ratified").
> >
> > +  * :c:macro:`RISCV_HWPROBE_EXT_ZIHPM`: The Zihpm extension version 2.0
> > +       is supported as defined in the RISC-V ISA manual.
> > +
> >    * :c:macro:`RISCV_HWPROBE_EXT_ZVE32X`: The Vector sub-extension Zve32x is
> >      supported, as defined by version 1.0 of the RISC-V Vector extension manual.
> >
> > diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> > index b706c8e47b02..098a815b3fd4 100644
> > --- a/arch/riscv/include/uapi/asm/hwprobe.h
> > +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> > @@ -72,6 +72,8 @@ struct riscv_hwprobe {
> >  #define                RISCV_HWPROBE_EXT_ZCF           (1ULL << 46)
> >  #define                RISCV_HWPROBE_EXT_ZCMOP         (1ULL << 47)
> >  #define                RISCV_HWPROBE_EXT_ZAWRS         (1ULL << 48)
> > +#define                RISCV_HWPROBE_EXT_ZICNTR        (1ULL << 49)
> > +#define                RISCV_HWPROBE_EXT_ZIHPM         (1ULL << 50)
> >  #define RISCV_HWPROBE_KEY_CPUPERF_0    5
> >  #define                RISCV_HWPROBE_MISALIGNED_UNKNOWN        (0 << 0)
> >  #define                RISCV_HWPROBE_MISALIGNED_EMULATED       (1 << 0)

The sort here, by number, is fine.

> > diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> > index 8d1b5c35d2a7..30aede1c90ff 100644
> > --- a/arch/riscv/kernel/sys_hwprobe.c
> > +++ b/arch/riscv/kernel/sys_hwprobe.c
> > @@ -118,6 +118,8 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
> >                 EXT_KEY(ZKSH);
> >                 EXT_KEY(ZKT);
> >                 EXT_KEY(ZTSO);
> > +               EXT_KEY(ZICNTR);
> > +               EXT_KEY(ZIHPM);
> 
> Conor, do we care about ordering?

I would rather that they were sorted alphabetically. Adding to the end
is nothing but a conflict generator and makes it harder to see what is
and what is not in the list. IIRC Palmer applied the patch I sent a few
weeks ago that sorted the entries in all of these EXT_KEY() lists.

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