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Date:   Wed, 04 Mar 2020 16:57:45 -0800 (PST)
Subject:     Re: [PATCH 3/8] riscv: add ARCH_SUPPORTS_DEBUG_PAGEALLOC support
In-Reply-To: <20200217083223.2011-4-zong.li@sifive.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>, aou@eecs.berkeley.edu,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        zong.li@sifive.com
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     zong.li@sifive.com
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On Mon, 17 Feb 2020 00:32:18 PST (-0800), zong.li@sifive.com wrote:
> ARCH_SUPPORTS_DEBUG_PAGEALLOC provides a hook to map and unmap
> pages for debugging purposes. Implement the __kernel_map_pages
> functions to fill the poison pattern.
>
> Signed-off-by: Zong Li <zong.li@sifive.com>
> ---
>  arch/riscv/Kconfig       |  3 +++
>  arch/riscv/mm/pageattr.c | 13 +++++++++++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 07bf1a7c0dd2..f524d7e60648 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -132,6 +132,9 @@ config ARCH_SELECT_MEMORY_MODEL
>  config ARCH_WANT_GENERAL_HUGETLB
>  	def_bool y
>
> +config ARCH_SUPPORTS_DEBUG_PAGEALLOC
> +	def_bool y
> +
>  config SYS_SUPPORTS_HUGETLBFS
>  	def_bool y
>
> diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> index 7be6cd67e2ef..728759eb530a 100644
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -172,3 +172,16 @@ int set_direct_map_default_noflush(struct page *page)
>
>  	return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
>  }
> +
> +void __kernel_map_pages(struct page *page, int numpages, int enable)
> +{
> +	if (!debug_pagealloc_enabled())
> +		return;
> +
> +	if (enable)
> +		__set_memory((unsigned long)page_address(page), numpages,
> +			     __pgprot(_PAGE_PRESENT), __pgprot(0));
> +	else
> +		__set_memory((unsigned long)page_address(page), numpages,
> +			     __pgprot(0), __pgprot(_PAGE_PRESENT));
> +}

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>