Re: [PATCH v3 03/20] riscv: add ISA extension parsing for scalar crypto

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On Tue, Nov 7, 2023 at 2:56 AM Clément Léger <cleger@xxxxxxxxxxxx> wrote:
>
> From: Evan Green <evan@xxxxxxxxxxxx>
>
> The Scalar Crypto specification defines Zk as a shorthand for the
> Zkn, Zkr and Zkt extensions. The same follows for both Zkn, Zks and Zbk,
> which are all shorthands for various other extensions. The detailed
> breakdown can be found in their dt-binding entries.
>
> Since Zkn also implies the Zbkb, Zbkc and Zbkx extensions, simply passing
> "zk" through a DT should enable all of Zbkb, Zbkc, Zbkx, Zkn, Zkr and Zkt.
> 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"
>
> riscv_isa_ext_data grows a pair of new members, to permit setting the
> relevant bits for "bundled" extensions, both while parsing the ISA string
> and the new dedicated extension properties.
>
> Co-developed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Signed-off-by: Evan Green <evan@xxxxxxxxxxxx>
> Signed-off-by: Clément Léger <cleger@xxxxxxxxxxxx>
> ---
>  arch/riscv/include/asm/hwcap.h |  16 ++++-
>  arch/riscv/kernel/cpufeature.c | 115 ++++++++++++++++++++++++++-------
>  2 files changed, 107 insertions(+), 24 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 6fc51c1b34cf..69cc659cf65e 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -60,8 +60,20 @@
>  #define RISCV_ISA_EXT_ZIHPM            42
>  #define RISCV_ISA_EXT_SMSTATEEN                43
>  #define RISCV_ISA_EXT_ZICOND           44
> +#define RISCV_ISA_EXT_ZBC              45
> +#define RISCV_ISA_EXT_ZBKB             46
> +#define RISCV_ISA_EXT_ZBKC             47
> +#define RISCV_ISA_EXT_ZBKX             48
> +#define RISCV_ISA_EXT_ZKND             49
> +#define RISCV_ISA_EXT_ZKNE             50
> +#define RISCV_ISA_EXT_ZKNH             51
> +#define RISCV_ISA_EXT_ZKR              52
> +#define RISCV_ISA_EXT_ZKSED            53
> +#define RISCV_ISA_EXT_ZKSH             54
> +#define RISCV_ISA_EXT_ZKT              55
>
>  #define RISCV_ISA_EXT_MAX              64
> +#define RISCV_ISA_EXT_INVALID          U32_MAX
>
>  #ifdef CONFIG_RISCV_M_MODE
>  #define RISCV_ISA_EXT_SxAIA            RISCV_ISA_EXT_SMAIA
> @@ -79,6 +91,8 @@ struct riscv_isa_ext_data {
>         const unsigned int id;
>         const char *name;
>         const char *property;
> +       const unsigned int *subset_ext_ids;
> +       const unsigned int subset_ext_size;
>  };
>
>  extern const struct riscv_isa_ext_data riscv_isa_ext[];
> @@ -89,7 +103,7 @@ unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
>
>  #define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
>
> -bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
> +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned int bit);
>  #define riscv_isa_extension_available(isa_bitmap, ext) \
>         __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index e3803822ab5a..0d78791288da 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -68,7 +68,7 @@ EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
>   *
>   * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
>   */
> -bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
> +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, unsigned int bit)
>  {
>         const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
>
> @@ -100,17 +100,53 @@ static bool riscv_isa_extension_check(int id)
>                         return false;
>                 }
>                 return true;
> +       case RISCV_ISA_EXT_INVALID:
> +               return false;
>         }
>
>         return true;
>  }
>
> -#define __RISCV_ISA_EXT_DATA(_name, _id) {     \
> -       .name = #_name,                         \
> -       .property = #_name,                     \
> -       .id = _id,                              \
> +#define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size) {     \
> +       .name = #_name,                                                         \
> +       .property = #_name,                                                     \
> +       .id = _id,                                                              \
> +       .subset_ext_ids = _subset_exts,                                         \
> +       .subset_ext_size = _subset_exts_size                                    \
>  }
>
> +#define __RISCV_ISA_EXT_DATA(_name, _id) _RISCV_ISA_EXT_DATA(_name, _id, NULL, 0)
> +
> +/* Used to declare pure "lasso" extension (Zk for instance) */
> +#define __RISCV_ISA_EXT_BUNDLE(_name, _bundled_exts) \
> +       _RISCV_ISA_EXT_DATA(_name, RISCV_ISA_EXT_INVALID, _bundled_exts, ARRAY_SIZE(_bundled_exts))
> +
> +static const unsigned int riscv_zk_bundled_exts[] = {
> +       RISCV_ISA_EXT_ZBKB,
> +       RISCV_ISA_EXT_ZBKC,
> +       RISCV_ISA_EXT_ZBKX,
> +       RISCV_ISA_EXT_ZKND,
> +       RISCV_ISA_EXT_ZKNE,
> +       RISCV_ISA_EXT_ZKR,
> +       RISCV_ISA_EXT_ZKT,
> +};
> +
> +static const unsigned int riscv_zkn_bundled_exts[] = {
> +       RISCV_ISA_EXT_ZBKB,
> +       RISCV_ISA_EXT_ZBKC,
> +       RISCV_ISA_EXT_ZBKX,
> +       RISCV_ISA_EXT_ZKND,
> +       RISCV_ISA_EXT_ZKNE,
> +       RISCV_ISA_EXT_ZKNH,
> +};
> +
> +static const unsigned int riscv_zks_bundled_exts[] = {
> +       RISCV_ISA_EXT_ZBKB,
> +       RISCV_ISA_EXT_ZBKC,
> +       RISCV_ISA_EXT_ZKSED,
> +       RISCV_ISA_EXT_ZKSH
> +};
> +
>  /*
>   * The canonical order of ISA extension names in the ISA string is defined in
>   * chapter 27 of the unprivileged specification.
> @@ -174,7 +210,21 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>         __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(zbkb, RISCV_ISA_EXT_ZBKB),
> +       __RISCV_ISA_EXT_DATA(zbkc, RISCV_ISA_EXT_ZBKC),
> +       __RISCV_ISA_EXT_DATA(zbkx, RISCV_ISA_EXT_ZBKX),
>         __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> +       __RISCV_ISA_EXT_BUNDLE(zk, riscv_zk_bundled_exts),
> +       __RISCV_ISA_EXT_BUNDLE(zkn, riscv_zkn_bundled_exts),
> +       __RISCV_ISA_EXT_DATA(zknd, RISCV_ISA_EXT_ZKND),
> +       __RISCV_ISA_EXT_DATA(zkne, RISCV_ISA_EXT_ZKNE),
> +       __RISCV_ISA_EXT_DATA(zknh, RISCV_ISA_EXT_ZKNH),
> +       __RISCV_ISA_EXT_DATA(zkr, RISCV_ISA_EXT_ZKR),
> +       __RISCV_ISA_EXT_BUNDLE(zks, riscv_zks_bundled_exts),
> +       __RISCV_ISA_EXT_DATA(zkt, RISCV_ISA_EXT_ZKT),
> +       __RISCV_ISA_EXT_DATA(zksed, RISCV_ISA_EXT_ZKSED),
> +       __RISCV_ISA_EXT_DATA(zksh, RISCV_ISA_EXT_ZKSH),
>         __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
>         __RISCV_ISA_EXT_DATA(smstateen, RISCV_ISA_EXT_SMSTATEEN),
>         __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> @@ -187,6 +237,27 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>
>  const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
>
> +static void __init match_isa_ext(const struct riscv_isa_ext_data *ext, const char *name,
> +                                const char *name_end, struct riscv_isainfo *isainfo)
> +{
> +       if ((name_end - name == strlen(ext->name)) &&
> +            !strncasecmp(name, ext->name, name_end - name)) {
> +               /*
> +                * If this is a bundle, enable all the ISA extensions that
> +                * comprise the bundle.
> +                */
> +               if (ext->subset_ext_size) {
> +                       for (int i = 0; i < ext->subset_ext_size; i++) {
> +                               if (riscv_isa_extension_check(ext->subset_ext_ids[i]))
> +                                       set_bit(ext->subset_ext_ids[i], isainfo->isa);
> +                       }
> +               }
> +
> +               if (riscv_isa_extension_check(ext->id))
> +                       set_bit(ext->id, isainfo->isa);
> +       }
> +}
> +
>  static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct riscv_isainfo *isainfo,
>                                           unsigned long *isa2hwcap, const char *isa)
>  {
> @@ -318,14 +389,6 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
>                 if (*isa == '_')
>                         ++isa;
>
> -#define SET_ISA_EXT_MAP(name, bit)                                             \
> -               do {                                                            \
> -                       if ((ext_end - ext == strlen(name)) &&                  \
> -                            !strncasecmp(ext, name, strlen(name)) &&           \
> -                            riscv_isa_extension_check(bit))                    \
> -                               set_bit(bit, isainfo->isa);                     \
> -               } while (false)                                                 \
> -
>                 if (unlikely(ext_err))
>                         continue;
>                 if (!ext_long) {
> @@ -337,10 +400,8 @@ static void __init riscv_parse_isa_string(unsigned long *this_hwcap, struct risc
>                         }
>                 } else {
>                         for (int i = 0; i < riscv_isa_ext_count; i++)
> -                               SET_ISA_EXT_MAP(riscv_isa_ext[i].name,
> -                                               riscv_isa_ext[i].id);
> +                               match_isa_ext(&riscv_isa_ext[i], ext, ext_end, isainfo);
>                 }
> -#undef SET_ISA_EXT_MAP
>         }
>  }
>
> @@ -439,18 +500,26 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
>                 }
>
>                 for (int i = 0; i < riscv_isa_ext_count; i++) {
> +                       const struct riscv_isa_ext_data ext = riscv_isa_ext[i];

Not a biggie, but a pointer would seem more appropriate to me than
copying the struct into a local.





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