linux-kernel - Re: [RFC PATCH 3/8] mm/ioremap: Define generic_ioremap_prot() and generic

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Date:   Sun, 16 Oct 2022 10:14:49 +0200
From:   Alexander Gordeev <agordeev@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Baoquan He <bhe@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        akpm@...ux-foundation.org, hch@...radead.org,
        wangkefeng.wang@...wei.com, schnelle@...ux.ibm.com,
        David.Laight@...lab.com, shorne@...il.com
Subject: Re: [RFC PATCH 3/8] mm/ioremap: Define generic_ioremap_prot() and
 generic_iounmap()

On Wed, Oct 12, 2022 at 12:09:39PM +0200, Christophe Leroy wrote:
> Define a generic version of ioremap_prot() and iounmap() that
> architectures can call after they have performed the necessary
> alteration to parameters and/or necessary verifications.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>

[...]

> diff --git a/mm/ioremap.c b/mm/ioremap.c
> index 8652426282cc..9f34a8f90b58 100644
> --- a/mm/ioremap.c
> +++ b/mm/ioremap.c
> @@ -11,8 +11,8 @@
>  #include <linux/io.h>
>  #include <linux/export.h>
>  
> -void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
> -			   unsigned long prot)
> +void __iomem *generic_ioremap_prot(phys_addr_t phys_addr, size_t size,
> +				   pgprot_t prot)
>  {
>  	unsigned long offset, vaddr;
>  	phys_addr_t last_addr;
> @@ -28,7 +28,7 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
>  	phys_addr -= offset;
>  	size = PAGE_ALIGN(size + offset);
>  
> -	if (!ioremap_allowed(phys_addr, size, prot))
> +	if (!ioremap_allowed(phys_addr, size, pgprot_val(prot)))
>  		return NULL;

It seems to me ioremap_allowed() is not needed anymore.
Whatever is checked here would move to architecture-
specific implementation.

>  	area = get_vm_area_caller(size, VM_IOREMAP,
> @@ -38,17 +38,24 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
>  	vaddr = (unsigned long)area->addr;
>  	area->phys_addr = phys_addr;
>  
> -	if (ioremap_page_range(vaddr, vaddr + size, phys_addr,
> -			       __pgprot(prot))) {
> +	if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot)) {
>  		free_vm_area(area);
>  		return NULL;
>  	}
>  
>  	return (void __iomem *)(vaddr + offset);
>  }
> +
> +#ifndef ioremap_prot

I guess, this is also needed:

#define ioremap_prot ioremap_prot

> +void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
> +			   unsigned long prot)
> +{
> +	return generic_ioremap_prot(phys_addr, size, __pgprot(prot));
> +}
>  EXPORT_SYMBOL(ioremap_prot);
> +#endif
>  
> -void iounmap(volatile void __iomem *addr)
> +void generic_iounmap(volatile void __iomem *addr)
>  {
>  	void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
>  
> @@ -58,4 +65,11 @@ void iounmap(volatile void __iomem *addr)
>  	if (is_vmalloc_addr(vaddr))
>  		vunmap(vaddr);
>  }
> +
> +#ifndef iounmap

Same here.

> +void iounmap(volatile void __iomem *addr)
> +{
> +	generic_iounmap(addr);
> +}
>  EXPORT_SYMBOL(iounmap);
> +#endif