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Date:   Fri, 29 Jun 2018 16:46:16 +0800
From:   Guo Ren <ren_guo@c-sky.com>
To:     Greentime Hu <green.hu@gmail.com>
Cc:     greentime@andestech.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] nds32: To implement these icache invalidation APIs
 since nds32 cores don't snoop data cache. This issue is found by Guo Ren.
 Based on the Documentation/core-api/cachetlb.rst and it says:
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On Thu, Jun 28, 2018 at 06:49:27PM +0800, Greentime Hu wrote:
> +void flush_icache_page(struct vm_area_struct *vma, struct page *page)
> +{
> +	unsigned long flags;
> +	local_irq_save(flags);
> +	cpu_cache_wbinval_page((unsigned long)page_address(page),
> +			       vma->vm_flags & VM_EXEC);
> +	local_irq_restore(flags);
> +}
> +EXPORT_SYMBOL(flush_icache_page);
> +
I'm afraid that the page_address(page) will return NULL for non-mapped page.

So I use kmap_atomic/kunmap_atomic here.

ref: https://github.com/c-sky/csky-linux/blob/master/arch/csky/abiv2/cacheflush.c

> +void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
> +	                     unsigned long addr, int len)
> +{
> +	unsigned long _addr = (unsigned long) page_address(page) + (addr & ~PAGE_MASK);
> +	flush_icache_range(_addr, _addr + len);
> +}

The same as above.

 Guo Ren