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Date:   Wed, 12 Jul 2023 11:46:52 +0100
From:   Conor Dooley <conor.dooley@microchip.com>
To:     Samuel Ortiz <sameo@rivosinc.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        <linux-riscv@lists.infradead.org>,
        "Hongren (Zenithal) Zheng" <i@zenithal.me>, <linux@rivosinc.com>,
        Andrew Jones <ajones@ventanamicro.com>,
        Heiko Stuebner <heiko.stuebner@vrull.eu>,
        Anup Patel <apatel@ventanamicro.com>,
        <linux-kernel@vger.kernel.org>, Guo Ren <guoren@kernel.org>,
        Atish Patra <atishp@rivosinc.com>,
        =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@rivosinc.com>,
        Evan Green <evan@rivosinc.com>, <devicetree@vger.kernel.org>,
        <sorear@fastmail.com>, Jiatai He <jiatai2021@iscas.ac.cn>
Subject: Re: [PATCH v4 1/4] RISC-V: Add Bitmanip/Scalar Crypto parsing from DT
Message-ID: <20230712-antibody-cried-1a6a68332c78@wendy>
References: <20230712084134.1648008-1-sameo@rivosinc.com>
 <20230712084134.1648008-2-sameo@rivosinc.com>
 <20230712-bulldozer-affected-199042dc3afd@wendy>
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On Wed, Jul 12, 2023 at 11:39:16AM +0100, Conor Dooley wrote:
> Hey Samuel, Evan,
>=20
> On Wed, Jul 12, 2023 at 10:41:17AM +0200, Samuel Ortiz wrote:
> > From: "Hongren (Zenithal) Zheng" <i@zenithal.me>
> >=20
> > Parse Zb/Zk related string from DT and output them to cpuinfo.
>=20
> One thing that has sprung to mind is that this is not limited to DT
> anymore, since the information could in theory come from ACPI too.
> Ditto the title I guess.
>=20
> > It is worth noting that the Scalar Crypto extension defines "zk" as a
> > shorthand for the Zkn, Zkr and Zkt extensions. Since the Zkn one also
> > implies the Zbkb, Zbkc and Zbkx extensions, simply passing the valid
> > "zk" extension name through a DT will enable all of the  Zbkb, Zbkc,
> > Zbkx, Zkn, Zkr and Zkt extensions.
> >=20
> > Also, since there currently is no mechanism to merge all enabled
> > extensions, the generated cpuinfo output could be relatively large.
> > For example, setting the "riscv,isa" DT property to "rv64imafdc_zk_zks"
> > will generate the following cpuinfo output:
> > "rv64imafdc_zbkb_zbkc_zbkx_zknd_zkne_zknh_zkr_zksed_zksh_zkt".
>=20
> On that note, I've created another version of what checking for
> supersets could look like, since it'll be needed either by my series or
> this one, depending on what gets merged first. I've yet to test the
> dedicated extensions part of it, but I wanted to get this out before I
> went looking at other fixes in the area.
>=20
> Evan, since it was you that commented on this stuff last time around,
> could you take another look? I'm still not keen on the "subset_of"
> arrays, but they're an improvement on what I had last time around for
> sure.

I would rather use the "property" member, renaming it to "properties",
but I didn't get the macro right in the bit of time I had this morning.
I'll try to think of a cleaner way...

Thanks,
Conor.

> (I took authorship since only the #defines & part of the commit
> message came from the original commit)
>=20
> -- >8 --
> From 2351c46fd1c9f6de312463875a4887f03d365b76 Mon Sep 17 00:00:00 2001
> From: Conor Dooley <conor.dooley@microchip.com>
> Date: Wed, 12 Jul 2023 11:25:36 +0100
> Subject: [PATCH] RISC-V: add detection of scalar crypto extensions
>=20
> It is worth noting that the Scalar Crypto extension defines "zk" as a
> shorthand for the Zkn, Zkr and Zkt extensions. Since the Zkn one also
> implies the Zbkb, Zbkc and Zbkx extensions, simply passing the valid
> "zk" extension name through a DT shold enable all of the Zbkb, Zbkc,
> Zbkx, Zkn, Zkr and Zkt extensions.
> For example, setting the "riscv,isa" DT property to "rv64imafdc_zk"
> should generate the following cpuinfo output:
> "rv64imafdc_zicntr_zicsr_zifencei_zihpm_zbkb_zbkc_zbkx_zknd_zkne_zknh_zkr=
_zkt"
>=20
> riscv_isa_ext_data grows a pair of new members, to permit searching for
> supersets of the extension in question, both while parsing the ISA
> string and the new dedicated extension properties.
>=20
> Co-developed-by: Hongren (Zenithal) Zheng <i@zenithal.me>
> Signed-off-by: Hongren (Zenithal) Zheng <i@zenithal.me>
> Co-developed-by: Samuel Ortiz <sameo@rivosinc.com>
> Signed-off-by: Samuel Ortiz <sameo@rivosinc.com>
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>  arch/riscv/include/asm/hwcap.h | 13 +++++
>  arch/riscv/kernel/cpufeature.c | 95 +++++++++++++++++++++++++++++-----
>  2 files changed, 94 insertions(+), 14 deletions(-)
>=20
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwca=
p.h
> index b7b58258f6c7..46d54f31e162 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -58,6 +58,17 @@
>  #define RISCV_ISA_EXT_ZICSR		40
>  #define RISCV_ISA_EXT_ZIFENCEI		41
>  #define RISCV_ISA_EXT_ZIHPM		42
> +#define RISCV_ISA_EXT_ZBC		43
> +#define RISCV_ISA_EXT_ZBKB		44
> +#define RISCV_ISA_EXT_ZBKC		45
> +#define RISCV_ISA_EXT_ZBKX		46
> +#define RISCV_ISA_EXT_ZKND		47
> +#define RISCV_ISA_EXT_ZKNE		48
> +#define RISCV_ISA_EXT_ZKNH		49
> +#define RISCV_ISA_EXT_ZKR		50
> +#define RISCV_ISA_EXT_ZKSED		51
> +#define RISCV_ISA_EXT_ZKSH		52
> +#define RISCV_ISA_EXT_ZKT		53
> =20
>  #define RISCV_ISA_EXT_MAX		64
> =20
> @@ -77,6 +88,8 @@ struct riscv_isa_ext_data {
>  	const unsigned int id;
>  	const char *name;
>  	const char *property;
> +	const unsigned int superset_count;
> +	const char **subset_of;
>  };
> =20
>  extern const struct riscv_isa_ext_data riscv_isa_ext[];
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeatur=
e.c
> index 5945dfc5f806..e862958d5495 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -103,8 +103,22 @@ static bool riscv_isa_extension_check(int id)
>  	.name =3D #_name,				\
>  	.property =3D #_name,			\
>  	.id =3D _id,				\
> +	.superset_count =3D 0,			\
> +	.subset_of =3D NULL,			\
>  }
> =20
> +#define __RISCV_ISA_EXT_DATA_SUBSET(_name, _id, _subset_of) {	\
> +	.name =3D #_name,						\
> +	.property =3D #_name,					\
> +	.id =3D _id,						\
> +	.superset_count =3D ARRAY_SIZE(_subset_of),		\
> +	.subset_of =3D _subset_of,				\
> +}
> +
> +static const char * const riscv_subset_of_zbk[] =3D { "zk", "zkn", "zks"=
 };
> +static const char * const riscv_subset_of_zkn[] =3D { "zk", "zkn" };
> +static const char * const riscv_subset_of_zk[]  =3D { "zk" };
> +static const char * const riscv_subset_of_zks[] =3D { "zks" };
>  /*
>   * The canonical order of ISA extension names in the ISA string is defin=
ed in
>   * chapter 27 of the unprivileged specification.
> @@ -167,7 +181,18 @@ const struct riscv_isa_ext_data riscv_isa_ext[] =3D {
>  	__RISCV_ISA_EXT_DATA(zihpm, RISCV_ISA_EXT_ZIHPM),
>  	__RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
>  	__RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
> +	__RISCV_ISA_EXT_DATA(zbc, RISCV_ISA_EXT_ZBC),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zbkb, RISCV_ISA_EXT_ZBKB, riscv_subset_of_z=
bk),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zbkc, RISCV_ISA_EXT_ZBKC, riscv_subset_of_z=
bk),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zbkx, RISCV_ISA_EXT_ZBKX, riscv_subset_of_z=
bk),
>  	__RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zknd, RISCV_ISA_EXT_ZKND, riscv_subset_of_z=
kn),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zkne, RISCV_ISA_EXT_ZKNE, riscv_subset_of_z=
kn),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zknh, RISCV_ISA_EXT_ZKNH, riscv_subset_of_z=
kn),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zkr, RISCV_ISA_EXT_ZKR, riscv_subset_of_zk),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zksed, RISCV_ISA_EXT_ZKSED, riscv_subset_of=
_zks),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zksh, RISCV_ISA_EXT_ZKSH, riscv_subset_of_z=
ks),
> +	__RISCV_ISA_EXT_DATA_SUBSET(zkt, RISCV_ISA_EXT_ZKT, riscv_subset_of_zk),
>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
>  	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
>  	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
> @@ -179,6 +204,31 @@ const struct riscv_isa_ext_data riscv_isa_ext[] =3D {
> =20
>  const size_t riscv_isa_ext_count =3D ARRAY_SIZE(riscv_isa_ext);
> =20
> +static inline int __init riscv_try_match_extension(const char *name, con=
st unsigned int bit,
> +						   const char *ext, const char *ext_end,
> +						   struct riscv_isainfo *isainfo)
> +{
> +	if ((ext_end - ext =3D=3D strlen(name)) && !strncasecmp(ext, name, strl=
en(name)) &&
> +	    riscv_isa_extension_check(bit)) {
> +		set_bit(bit, isainfo->isa);
> +		return 0;
> +	}
> +
> +	return -ENOENT;
> +}
> +
> +static inline void __init riscv_try_match_supersets(struct riscv_isa_ext=
_data ext_data,
> +						    const char *ext, const char *ext_end,
> +						    struct riscv_isainfo *isainfo)
> +{
> +	for (int i =3D 0; i < ext_data.superset_count; i++) {
> +		const char *superset =3D ext_data.subset_of[i];
> +		const int bit =3D ext_data.id;
> +
> +		riscv_try_match_extension(superset, bit, ext, ext_end, isainfo);
> +	}
> +}
> +
>  static void __init riscv_parse_isa_string(unsigned long *this_hwcap, str=
uct riscv_isainfo *isainfo,
>  					  unsigned long *isa2hwcap, const char *isa)
>  {
> @@ -310,16 +360,9 @@ static void __init riscv_parse_isa_string(unsigned l=
ong *this_hwcap, struct risc
>  		if (*isa =3D=3D '_')
>  			++isa;
> =20
> -#define SET_ISA_EXT_MAP(name, bit)						\
> -		do {								\
> -			if ((ext_end - ext =3D=3D sizeof(name) - 1) &&		\
> -			     !strncasecmp(ext, name, sizeof(name) - 1) &&	\
> -			     riscv_isa_extension_check(bit))			\
> -				set_bit(bit, isainfo->isa);			\
> -		} while (false)							\
> -
>  		if (unlikely(ext_err))
>  			continue;
> +
>  		if (!ext_long) {
>  			int nr =3D tolower(*ext) - 'a';
> =20
> @@ -327,12 +370,21 @@ static void __init riscv_parse_isa_string(unsigned =
long *this_hwcap, struct risc
>  				*this_hwcap |=3D isa2hwcap[nr];
>  				set_bit(nr, isainfo->isa);
>  			}
> -		} else {
> +
>  			for (int i =3D 0; i < riscv_isa_ext_count; i++)
> -				SET_ISA_EXT_MAP(riscv_isa_ext[i].name,
> -						riscv_isa_ext[i].id);
> +				riscv_try_match_supersets(riscv_isa_ext[i], ext, ext_end, isainfo);
> +		} else {
> +			for (int i =3D 0; i < riscv_isa_ext_count; i++) {
> +				const char *name =3D riscv_isa_ext[i].name;
> +				const int bit =3D riscv_isa_ext[i].id;
> +				int ret;
> +
> +				ret =3D riscv_try_match_extension(name, bit, ext, ext_end, isainfo);
> +				if (ret && riscv_isa_ext[i].superset_count)
> +					riscv_try_match_supersets(riscv_isa_ext[i], ext,
> +								  ext_end, isainfo);
> +			}
>  		}
> -#undef SET_ISA_EXT_MAP
>  	}
>  }
> =20
> @@ -434,8 +486,23 @@ static int __init riscv_fill_hwcap_from_ext_list(uns=
igned long *isa2hwcap)
>  			continue;
> =20
>  		for (int i =3D 0; i < riscv_isa_ext_count; i++) {
> -			if (of_property_match_string(cpu_node, "riscv,isa-extensions",
> -						     riscv_isa_ext[i].property) < 0)
> +			struct riscv_isa_ext_data ext =3D riscv_isa_ext[i];
> +			int ret;
> +
> +			ret =3D of_property_match_string(cpu_node, "riscv,isa-extensions",
> +						       ext.property);
> +
> +			if (ret < 0 && ext.superset_count) {
> +				for (int j =3D 0; j < ext.superset_count; j++) {
> +					ret =3D of_property_match_string(cpu_node,
> +								       "riscv,isa-extensions",
> +								       ext.subset_of[j]);
> +					if (ret >=3D 0)
> +						break;
> +				}
> +			}
> +
> +			if (ret < 0)
>  				continue;
> =20
>  			if (!riscv_isa_extension_check(riscv_isa_ext[i].id))
> --=20
> 2.40.1
>=20
>=20


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