Commit 2592dbbb authored by Juergen Gross's avatar Juergen Gross Committed by David Vrabel
Browse files

mm: provide early_memremap_ro to establish read-only mapping 



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: default avatarJuergen Gross <jgross@suse.com>
Acked-by: default avatarKonrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 4b9c1537

include/asm-generic/early_ioremap.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

include/asm-generic/fixmap.h

+3 −0
Original line number Diff line number Diff line
@@ -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

mm/early_ioremap.c

+12 −0
Original line number Diff line number Diff line
@@ -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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