linux-kernel - Re: [PATCH 02/12] riscv: allow different stages with alternatives

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Message-ID: <CAJF2gTQKsJ00MAyXGnBXR-tK1pAnHeuEr6Se79OYN4_kvPjjFQ@mail.gmail.com>
Date:   Mon, 16 May 2022 14:51:24 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Wei Fu <wefu@...hat.com>, liush <liush@...winnertech.com>,
        Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>,
        Drew Fustini <drew@...gleboard.org>,
        Christoph Hellwig <hch@....de>, Arnd Bergmann <arnd@...db.de>,
        Chen-Yu Tsai <wens@...e.org>,
        Maxime Ripard <maxime@...no.tech>,
        Greg Favor <gfavor@...tanamicro.com>,
        Andrea Mondelli <andrea.mondelli@...wei.com>,
        Jonathan Behrens <behrensj@....edu>,
        "Xinhaoqu (Freddie)" <xinhaoqu@...wei.com>,
        Nick Kossifidis <mick@....forth.gr>,
        Allen Baum <allen.baum@...erantotech.com>,
        Josh Scheid <jscheid@...tanamicro.com>,
        Richard Trauben <rtrauben@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Christoph Muellner <cmuellner@...ux.com>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>
Subject: Re: [PATCH 02/12] riscv: allow different stages with alternatives

Reviewed-by: Guo Ren <guoren@...nel.org>

On Thu, May 12, 2022 at 3:29 AM Heiko Stuebner <heiko@...ech.de> wrote:
>
> Future features may need to be applied at a different
> time during boot, so allow defining stages for alternatives
> and handling them differently depending on the stage.
>
> Also make the alternatives-location more flexible so that
> future stages may provide their own location.
>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> Reviewed-by: Philipp Tomsich <philipp.tomsich@...ll.eu>
> ---
>  arch/riscv/errata/sifive/errata.c    |  3 ++-
>  arch/riscv/include/asm/alternative.h |  5 ++++-
>  arch/riscv/kernel/alternative.c      | 26 +++++++++++++++++---------
>  3 files changed, 23 insertions(+), 11 deletions(-)
>
> diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> index f5e5ae70e829..4fe03ac41fd7 100644
> --- a/arch/riscv/errata/sifive/errata.c
> +++ b/arch/riscv/errata/sifive/errata.c
> @@ -80,7 +80,8 @@ static void __init warn_miss_errata(u32 miss_errata)
>  }
>
>  void __init sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
> -                                    unsigned long archid, unsigned long impid)
> +                                    unsigned long archid, unsigned long impid,
> +                                    unsigned int stage)
>  {
>         struct alt_entry *alt;
>         u32 cpu_req_errata = sifive_errata_probe(archid, impid);
> diff --git a/arch/riscv/include/asm/alternative.h b/arch/riscv/include/asm/alternative.h
> index 7b42bcef0ecf..0ff550667e94 100644
> --- a/arch/riscv/include/asm/alternative.h
> +++ b/arch/riscv/include/asm/alternative.h
> @@ -19,6 +19,8 @@
>  #include <linux/stddef.h>
>  #include <asm/hwcap.h>
>
> +#define RISCV_ALTERNATIVES_BOOT                0 /* alternatives applied during regular boot */
> +
>  void __init apply_boot_alternatives(void);
>
>  struct alt_entry {
> @@ -35,7 +37,8 @@ struct errata_checkfunc_id {
>  };
>
>  void sifive_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
> -                             unsigned long archid, unsigned long impid);
> +                             unsigned long archid, unsigned long impid,
> +                             unsigned int stage);
>
>  #else /* CONFIG_RISCV_ALTERNATIVE */
>
> diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c
> index e8b4a0fe488c..02db62f55bac 100644
> --- a/arch/riscv/kernel/alternative.c
> +++ b/arch/riscv/kernel/alternative.c
> @@ -22,8 +22,8 @@ static struct cpu_manufacturer_info_t {
>  } cpu_mfr_info;
>
>  static void (*vendor_patch_func)(struct alt_entry *begin, struct alt_entry *end,
> -                                unsigned long archid,
> -                                unsigned long impid) __initdata;
> +                                unsigned long archid, unsigned long impid,
> +                                unsigned int stage) __initdata;
>
>  static inline void __init riscv_fill_cpu_mfr_info(void)
>  {
> @@ -58,6 +58,18 @@ static void __init init_alternative(void)
>   * a feature detect on the boot CPU). No need to worry about other CPUs
>   * here.
>   */
> +static void __init _apply_alternatives(struct alt_entry *begin,
> +                                      struct alt_entry *end,
> +                                      unsigned int stage)
> +{
> +       if (!vendor_patch_func)
> +               return;
> +
> +       vendor_patch_func(begin, end,
> +                         cpu_mfr_info.arch_id, cpu_mfr_info.imp_id,
> +                         stage);
> +}
> +
>  void __init apply_boot_alternatives(void)
>  {
>         /* If called on non-boot cpu things could go wrong */
> @@ -65,11 +77,7 @@ void __init apply_boot_alternatives(void)
>
>         init_alternative();
>
> -       if (!vendor_patch_func)
> -               return;
> -
> -       vendor_patch_func((struct alt_entry *)__alt_start,
> -                         (struct alt_entry *)__alt_end,
> -                         cpu_mfr_info.arch_id, cpu_mfr_info.imp_id);
> +       _apply_alternatives((struct alt_entry *)__alt_start,
> +                           (struct alt_entry *)__alt_end,
> +                           RISCV_ALTERNATIVES_BOOT);
>  }
> -
> --
> 2.35.1
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/