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: Juergen Gross <jgross@suse.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/include/asm-generic/early_ioremap.h b/include/asm-generic/early_ioremap.h
index a5de55c..316bd04 100644 (file)
--- 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 --cc include/asm-generic/fixmap.h
Simple merge

diff --cc mm/early_ioremap.c
Simple merge