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SubjectRe: [Patch V6 12/16] mm: provide early_memremap_ro to establish read-only mapping
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Hi MM maintainers,

this patch is the last requiring an ack for the series to go in.
Could you please comment?


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@suse.com>
> Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: linux-mm@kvack.org
> Cc: linux-arch@vger.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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