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Message-ID: <CAAhSdy2kcFKC2-QTE28dujcBKybo_dxKrc+_+m3s97cr2mvxzg@mail.gmail.com>
Date: Tue, 15 Mar 2022 08:39:05 +0530
From: Anup Patel <anup@...infault.org>
To: Atish Patra <atishp@...osinc.com>
Cc: "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
Heiko Stuebner <heiko@...ech.de>,
Albert Ou <aou@...s.berkeley.edu>,
Atish Patra <atishp@...shpatra.org>,
Damien Le Moal <damien.lemoal@....com>,
DTML <devicetree@...r.kernel.org>,
Jisheng Zhang <jszhang@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
linux-riscv <linux-riscv@...ts.infradead.org>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v6 4/6] RISC-V: Implement multi-letter ISA extension
probing framework
On Tue, Mar 15, 2022 at 2:09 AM Atish Patra <atishp@...osinc.com> wrote:
>
> Multi-letter extensions can be probed using exising
> riscv_isa_extension_available API now. It doesn't support versioning
> right now as there is no use case for it.
> Individual extension specific implementation will be added during
> each extension support.
>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Signed-off-by: Atish Patra <atishp@...osinc.com>
Reviewed-by: Anup Patel <anup@...infault.org>
Regards,
Anup
> ---
> arch/riscv/include/asm/hwcap.h | 18 ++++++++++++++++++
> arch/riscv/kernel/cpufeature.c | 22 ++++++++++++++++------
> 2 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 5ce50468aff1..170bd80da520 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -34,7 +34,25 @@ extern unsigned long elf_hwcap;
> #define RISCV_ISA_EXT_s ('s' - 'a')
> #define RISCV_ISA_EXT_u ('u' - 'a')
>
> +/*
> + * Increse this to higher value as kernel support more ISA extensions.
> + */
> #define RISCV_ISA_EXT_MAX 64
> +#define RISCV_ISA_EXT_NAME_LEN_MAX 32
> +
> +/* The base ID for multi-letter ISA extensions */
> +#define RISCV_ISA_EXT_BASE 26
> +
> +/*
> + * This enum represent the logical ID for each multi-letter RISC-V ISA extension.
> + * The logical ID should start from RISCV_ISA_EXT_BASE and must not exceed
> + * RISCV_ISA_EXT_MAX. 0-25 range is reserved for single letter
> + * extensions while all the multi-letter extensions should define the next
> + * available logical extension id.
> + */
> +enum riscv_isa_ext_id {
> + RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
> +};
>
> unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index b0df7eff47f7..3455fdfd680e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -83,7 +83,7 @@ void __init riscv_fill_hwcap(void)
>
> for_each_of_cpu_node(node) {
> unsigned long this_hwcap = 0;
> - unsigned long this_isa = 0;
> + DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
>
> if (riscv_of_processor_hartid(node) < 0)
> continue;
> @@ -100,6 +100,7 @@ void __init riscv_fill_hwcap(void)
> if (!strncmp(isa, "rv64", 4))
> isa += 4;
> #endif
> + bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
> for (; *isa; ++isa) {
> const char *ext = isa++;
> const char *ext_end = isa;
> @@ -172,12 +173,20 @@ void __init riscv_fill_hwcap(void)
> if (*isa != '_')
> --isa;
>
> +#define SET_ISA_EXT_MAP(name, bit) \
> + do { \
> + if ((ext_end - ext == sizeof(name) - 1) && \
> + !memcmp(ext, name, sizeof(name) - 1)) \
> + set_bit(bit, this_isa); \
> + } while (false) \
> +
> if (unlikely(ext_err))
> continue;
> if (!ext_long) {
> this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
> - this_isa |= (1UL << (*ext - 'a'));
> + set_bit(*ext - 'a', this_isa);
> }
> +#undef SET_ISA_EXT_MAP
> }
>
> /*
> @@ -190,10 +199,11 @@ void __init riscv_fill_hwcap(void)
> else
> elf_hwcap = this_hwcap;
>
> - if (riscv_isa[0])
> - riscv_isa[0] &= this_isa;
> + if (bitmap_weight(riscv_isa, RISCV_ISA_EXT_MAX))
> + bitmap_and(riscv_isa, riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
> else
> - riscv_isa[0] = this_isa;
> + bitmap_copy(riscv_isa, this_isa, RISCV_ISA_EXT_MAX);
> +
> }
>
> /* We don't support systems with F but without D, so mask those out
> @@ -207,7 +217,7 @@ void __init riscv_fill_hwcap(void)
> for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
> if (riscv_isa[0] & BIT_MASK(i))
> print_str[j++] = (char)('a' + i);
> - pr_info("riscv: ISA extensions %s\n", print_str);
> + pr_info("riscv: base ISA extensions %s\n", print_str);
>
> memset(print_str, 0, sizeof(print_str));
> for (i = 0, j = 0; i < NUM_ALPHA_EXTS; i++)
> --
> 2.30.2
>
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