linux-kernel - Re: [PATCH] riscv: Consistify protect_kernel_linear_mapping_text

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Message-ID: <mhng-b16d1d5a-0ddf-4717-bde7-114e49d508e1@palmerdabbelt-glaptop>
Date:   Thu, 06 May 2021 00:16:22 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     geert+renesas@...der.be
CC:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        vitaly.wool@...sulko.com, alex@...ti.fr,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        geert+renesas@...der.be
Subject:     Re: [PATCH] riscv: Consistify protect_kernel_linear_mapping_text_rodata() use

On Thu, 29 Apr 2021 08:10:04 PDT (-0700), geert+renesas@...der.be wrote:
> The various uses of protect_kernel_linear_mapping_text_rodata() are
> not consistent:
>   - Its definition depends on "64BIT && !XIP_KERNEL",
>   - Its forward declaration depends on MMU,
>   - Its single caller depends on "STRICT_KERNEL_RWX && 64BIT && MMU &&
>     !XIP_KERNEL".
>
> Fix this by settling on the dependencies of the caller, which can be
> simplified as STRICT_KERNEL_RWX depends on "MMU && !XIP_KERNEL".
> Provide a dummy definition, as the caller is protected by
> "IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)" instead of "#ifdef
> CONFIG_STRICT_KERNEL_RWX".
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> Only tested on K210 (SiPeed MAIX BiT).
> ---
>  arch/riscv/include/asm/set_memory.h | 7 ++++++-
>  arch/riscv/kernel/setup.c           | 2 --
>  arch/riscv/mm/init.c                | 2 +-
>  3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
> index a9c56776fa0e74d6..086f757e8ba3cc69 100644
> --- a/arch/riscv/include/asm/set_memory.h
> +++ b/arch/riscv/include/asm/set_memory.h
> @@ -17,7 +17,6 @@ int set_memory_x(unsigned long addr, int numpages);
>  int set_memory_nx(unsigned long addr, int numpages);
>  int set_memory_rw_nx(unsigned long addr, int numpages);
>  void protect_kernel_text_data(void);
> -void protect_kernel_linear_mapping_text_rodata(void);
>  #else
>  static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
>  static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
> @@ -27,6 +26,12 @@ static inline void protect_kernel_text_data(void) {}
>  static inline int set_memory_rw_nx(unsigned long addr, int numpages) { return 0; }
>  #endif
>
> +#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
> +void protect_kernel_linear_mapping_text_rodata(void);
> +#else
> +static inline void protect_kernel_linear_mapping_text_rodata(void) {}
> +#endif
> +
>  int set_direct_map_invalid_noflush(struct page *page);
>  int set_direct_map_default_noflush(struct page *page);
>  bool kernel_page_present(struct page *page);
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 7b31779101f662e4..03901d3a8b027343 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -293,9 +293,7 @@ void __init setup_arch(char **cmdline_p)
>
>  	if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
>  		protect_kernel_text_data();
> -#if defined(CONFIG_64BIT) && defined(CONFIG_MMU) && !defined(CONFIG_XIP_KERNEL)
>  		protect_kernel_linear_mapping_text_rodata();
> -#endif
>  	}
>
>  #ifdef CONFIG_SWIOTLB
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 3ebc0f5d2b73b42b..6cc0421a5d0ef4a3 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -646,7 +646,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>  #endif
>  }
>
> -#if defined(CONFIG_64BIT) && !defined(CONFIG_XIP_KERNEL)
> +#if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)
>  void protect_kernel_linear_mapping_text_rodata(void)
>  {
>  	unsigned long text_start = (unsigned long)lm_alias(_start);

Thanks, this is on for-next.