Re: [PATCH] riscv: Add HAVE_IOREMAP_PROT support

From: Alexandre Ghiti <alex@ghiti.fr>
To: guoren@kernel.org, palmer@rivosinc.com, paul.walmsley@sifive.com,
	falcon@tinylab.org, bjorn@kernel.org, conor.dooley@microchip.com
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH] riscv: Add HAVE_IOREMAP_PROT support
Date: Mon, 17 Jul 2023 11:07:13 +0200	[thread overview]
Message-ID: <bb296a8e-4f84-f45d-8f46-5acfa73022d9@ghiti.fr> (raw)
In-Reply-To: <20230716152033.3713581-1-guoren@kernel.org>

Hi Guo,

On 16/07/2023 17:20, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> Add pte_pgprot macro, then riscv could have HAVE_IOREMAP_PROT,
> which will enable generic_access_phys() code, it is useful for
> debug, eg, gdb.

I don't understand, we already have the generic ioremap_prot() 
implementation since we select GENERIC_IOREMAP: shouldn't 
HAVE_IOREMAP_PROT imply that we have our own implementation?

Thanks,

Alex

> Because generic_access_phys() would call ioremap_prot()->
> pgprot_nx() to disable excutable attribute, add definition
> of pgprot_nx() for riscv.
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> ---
>   .../features/vm/ioremap_prot/arch-support.txt     |  2 +-
>   arch/riscv/Kconfig                                |  1 +
>   arch/riscv/include/asm/pgtable.h                  | 15 +++++++++++++++
>   3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/features/vm/ioremap_prot/arch-support.txt b/Documentation/features/vm/ioremap_prot/arch-support.txt
> index a24149e59d73..ea8c8a361455 100644
> --- a/Documentation/features/vm/ioremap_prot/arch-support.txt
> +++ b/Documentation/features/vm/ioremap_prot/arch-support.txt
> @@ -21,7 +21,7 @@
>       |    openrisc: | TODO |
>       |      parisc: | TODO |
>       |     powerpc: |  ok  |
> -    |       riscv: | TODO |
> +    |       riscv: |  ok  |
>       |        s390: |  ok  |
>       |          sh: |  ok  |
>       |       sparc: | TODO |
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 4c07b9189c86..15900fa20797 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -117,6 +117,7 @@ config RISCV
>   	select HAVE_FUNCTION_ERROR_INJECTION
>   	select HAVE_GCC_PLUGINS
>   	select HAVE_GENERIC_VDSO if MMU && 64BIT
> +	select HAVE_IOREMAP_PROT
>   	select HAVE_IRQ_TIME_ACCOUNTING
>   	select HAVE_KPROBES if !XIP_KERNEL
>   	select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 75970ee2bda2..c9552a161f90 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -415,6 +415,11 @@ static inline pte_t pte_mkhuge(pte_t pte)
>   	return pte;
>   }
>   
> +static inline pgprot_t pte_pgprot(pte_t pte)
> +{
> +	return __pgprot(pte_val(pte) & ~_PAGE_PFN_MASK);
> +}
> +
>   #ifdef CONFIG_NUMA_BALANCING
>   /*
>    * See the comment in include/asm-generic/pgtable.h
> @@ -573,6 +578,16 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
>   	return ptep_test_and_clear_young(vma, address, ptep);
>   }
>   
> +#define pgprot_nx pgprot_nx
> +static inline pgprot_t pgprot_nx(pgprot_t _prot)
> +{
> +	unsigned long prot = pgprot_val(_prot);
> +
> +	prot &= ~_PAGE_EXEC;
> +
> +	return __pgprot(prot);
> +}
> +
>   #define pgprot_noncached pgprot_noncached
>   static inline pgprot_t pgprot_noncached(pgprot_t _prot)
>   {

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