linux-kernel - Re: [Patch V6 12/16] mm: provide early_memremap

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Date:	Wed, 29 Jul 2015 11:20:13 +0200
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	linux-mm@...ck.org, linux-arch@...r.kernel.org
Cc:	xen-devel@...ts.xensource.com, konrad.wilk@...cle.com,
	david.vrabel@...rix.com, boris.ostrovsky@...cle.com
Subject: Re: [Patch V6 12/16] mm: provide early_memremap_ro to establish
 read-only mapping

On 07/21/2015 06:49 AM, Juergen Gross wrote:
> Hi MM maintainers,
>
> this patch is the last requiring an ack for the series to go in.
> Could you please comment?

PING?

>
>
> Juergen
>
> On 07/17/2015 06:51 AM, Juergen Gross wrote:
>> During early boot as Xen pv domain the kernel needs to map some page
>> tables supplied by the hypervisor read only. This is needed to be
>> able to relocate some data structures conflicting with the physical
>> memory map especially on systems with huge RAM (above 512GB).
>>
>> Provide the function early_memremap_ro() to provide this read only
>> mapping.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@...cle.com>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: linux-mm@...ck.org
>> Cc: linux-arch@...r.kernel.org
>> ---
>>   include/asm-generic/early_ioremap.h |  2 ++
>>   include/asm-generic/fixmap.h        |  3 +++
>>   mm/early_ioremap.c                  | 12 ++++++++++++
>>   3 files changed, 17 insertions(+)
>>
>> diff --git a/include/asm-generic/early_ioremap.h
>> b/include/asm-generic/early_ioremap.h
>> index a5de55c..316bd04 100644
>> --- a/include/asm-generic/early_ioremap.h
>> +++ b/include/asm-generic/early_ioremap.h
>> @@ -11,6 +11,8 @@ extern void __iomem *early_ioremap(resource_size_t
>> phys_addr,
>>                      unsigned long size);
>>   extern void *early_memremap(resource_size_t phys_addr,
>>                   unsigned long size);
>> +extern void *early_memremap_ro(resource_size_t phys_addr,
>> +                   unsigned long size);
>>   extern void early_iounmap(void __iomem *addr, unsigned long size);
>>   extern void early_memunmap(void *addr, unsigned long size);
>>
>> diff --git a/include/asm-generic/fixmap.h b/include/asm-generic/fixmap.h
>> index f23174f..1cbb833 100644
>> --- a/include/asm-generic/fixmap.h
>> +++ b/include/asm-generic/fixmap.h
>> @@ -46,6 +46,9 @@ static inline unsigned long virt_to_fix(const
>> unsigned long vaddr)
>>   #ifndef FIXMAP_PAGE_NORMAL
>>   #define FIXMAP_PAGE_NORMAL PAGE_KERNEL
>>   #endif
>> +#if !defined(FIXMAP_PAGE_RO) && defined(PAGE_KERNEL_RO)
>> +#define FIXMAP_PAGE_RO PAGE_KERNEL_RO
>> +#endif
>>   #ifndef FIXMAP_PAGE_NOCACHE
>>   #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
>>   #endif
>> diff --git a/mm/early_ioremap.c b/mm/early_ioremap.c
>> index e10ccd2..0cfadaf 100644
>> --- a/mm/early_ioremap.c
>> +++ b/mm/early_ioremap.c
>> @@ -217,6 +217,13 @@ early_memremap(resource_size_t phys_addr,
>> unsigned long size)
>>       return (__force void *)__early_ioremap(phys_addr, size,
>>                              FIXMAP_PAGE_NORMAL);
>>   }
>> +#ifdef FIXMAP_PAGE_RO
>> +void __init *
>> +early_memremap_ro(resource_size_t phys_addr, unsigned long size)
>> +{
>> +    return (__force void *)__early_ioremap(phys_addr, size,
>> FIXMAP_PAGE_RO);
>> +}
>> +#endif
>>   #else /* CONFIG_MMU */
>>
>>   void __init __iomem *
>> @@ -231,6 +238,11 @@ early_memremap(resource_size_t phys_addr,
>> unsigned long size)
>>   {
>>       return (void *)phys_addr;
>>   }
>> +void __init *
>> +early_memremap_ro(resource_size_t phys_addr, unsigned long size)
>> +{
>> +    return (void *)phys_addr;
>> +}
>>
>>   void __init early_iounmap(void __iomem *addr, unsigned long size)
>>   {
>>
>
> --
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