linux-kernel - Re: [PATCH v2 1/2] riscv: Support R_RISCV_ADD64 and R_RISCV

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Message-ID: <CAJ+HfNj+dFE70O49-wZC1ckGSVo8Fb4_UcaeZocQABfKkyHmSg@mail.gmail.com>
Date:   Thu, 9 Jul 2020 08:22:03 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Emil Renner Berthing <kernel@...il.dk>
Cc:     linux-riscv <linux-riscv@...ts.infradead.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] riscv: Support R_RISCV_ADD64 and R_RISCV_SUB64 relocs

On Wed, 8 Jul 2020 at 23:10, Emil Renner Berthing <kernel@...il.dk> wrote:
>
> These are needed for the __jump_table in modules using
> static keys/jump-labels with the layout from
> HAVE_ARCH_JUMP_LABEL_RELATIVE on 64bit kernels.
>
> Signed-off-by: Emil Renner Berthing <kernel@...il.dk>

Reviewed-by: Björn Töpel <bjorn.topel@...il.com>
Tested-by: Björn Töpel <bjorn.topel@...il.com>

> ---
>
> Tested on the HiFive Unleashed board.
>
> This patch is new in v2. It fixes an error loading modules
> containing static keys found by Björn Töpel.
>
>  arch/riscv/kernel/module.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 7191342c54da..104fba889cf7 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -263,6 +263,13 @@ static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
>         return 0;
>  }
>
> +static int apply_r_riscv_add64_rela(struct module *me, u32 *location,
> +                                   Elf_Addr v)
> +{
> +       *(u64 *)location += (u64)v;
> +       return 0;
> +}
> +
>  static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
>                                     Elf_Addr v)
>  {
> @@ -270,6 +277,13 @@ static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
>         return 0;
>  }
>
> +static int apply_r_riscv_sub64_rela(struct module *me, u32 *location,
> +                                   Elf_Addr v)
> +{
> +       *(u64 *)location -= (u64)v;
> +       return 0;
> +}
> +
>  static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
>                                 Elf_Addr v) = {
>         [R_RISCV_32]                    = apply_r_riscv_32_rela,
> @@ -290,7 +304,9 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
>         [R_RISCV_RELAX]                 = apply_r_riscv_relax_rela,
>         [R_RISCV_ALIGN]                 = apply_r_riscv_align_rela,
>         [R_RISCV_ADD32]                 = apply_r_riscv_add32_rela,
> +       [R_RISCV_ADD64]                 = apply_r_riscv_add64_rela,
>         [R_RISCV_SUB32]                 = apply_r_riscv_sub32_rela,
> +       [R_RISCV_SUB64]                 = apply_r_riscv_sub64_rela,
>  };
>
>  int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> --
> 2.27.0
>