linux-kernel - Re: [PATCH v8 1/2] riscv: Introduce set_kernel

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Date:   Fri, 25 Jun 2021 21:29:02 +0800
From:   Jisheng Zhang <jszhang3@...l.ustc.edu.cn>
To:     Alexandre Ghiti <alex@...ti.fr>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Jisheng Zhang <jszhang@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 1/2] riscv: Introduce set_kernel_memory helper

On Thu, 24 Jun 2021 14:00:40 +0200
Alexandre Ghiti <alex@...ti.fr> wrote:

> This helper should be used for setting permissions to the kernel
> mapping as it takes pointers as arguments and then avoids explicit cast
> to unsigned long needed for the set_memory_* API.
> 
> Suggested-by: Christoph Hellwig <hch@...radead.org>
> Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
> Reviewed-by: Anup Patel <anup@...infault.org>

Reviewed-by: Jisheng Zhang <jszhang@...nel.org>

> ---
>  arch/riscv/include/asm/set_memory.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
> index 9d4d455726d4..96e317dcab13 100644
> --- a/arch/riscv/include/asm/set_memory.h
> +++ b/arch/riscv/include/asm/set_memory.h
> @@ -17,6 +17,16 @@ 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);
> +static __always_inline int set_kernel_memory(char *startp, char *endp,
> +					     int (*set_memory)(unsigned long start,
> +							       int num_pages))
> +{
> +	unsigned long start = (unsigned long)startp;
> +	unsigned long end = (unsigned long)endp;
> +	int num_pages = PAGE_ALIGN(end - start) >> PAGE_SHIFT;
> +
> +	return set_memory(start, num_pages);
> +}
>  #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; }
> @@ -24,6 +34,12 @@ static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
>  static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
>  static inline void protect_kernel_text_data(void) {}
>  static inline int set_memory_rw_nx(unsigned long addr, int numpages) { return 0; }
> +static inline int set_kernel_memory(char *startp, char *endp,
> +				    int (*set_memory)(unsigned long start,
> +						      int num_pages))
> +{
> +	return 0;
> +}
>  #endif
>  
>  #if defined(CONFIG_64BIT) && defined(CONFIG_STRICT_KERNEL_RWX)