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

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Message-ID: <d00b3561-8f79-23a7-ac87-89766adf6513@csgroup.eu>
Date:   Sun, 16 Oct 2022 16:54:32 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Alexander Gordeev <agordeev@...ux.ibm.com>
CC:     Baoquan He <bhe@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "hch@...radead.org" <hch@...radead.org>,
        "wangkefeng.wang@...wei.com" <wangkefeng.wang@...wei.com>,
        "schnelle@...ux.ibm.com" <schnelle@...ux.ibm.com>,
        "David.Laight@...lab.com" <David.Laight@...lab.com>,
        "shorne@...il.com" <shorne@...il.com>
Subject: Re: [RFC PATCH 3/8] mm/ioremap: Define generic_ioremap_prot() and
 generic_iounmap()



Le 16/10/2022 à 10:14, Alexander Gordeev a écrit :
> 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.

Yes can probably be removed as a follow-up. I didn't want to change 
existing implementations at the first place, and see what it looks like 
once all architectures have been looked at.

> 
>>   	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

Why would it need that ? We are in ioremap.c, any define done here is 
exclusively seen here in this C file. It's not like a header file.

> 
>> +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.

Same, I don't see what it would add.

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