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60901df3ae
Commit 1084b1988d (xen: Add Xen specific
page definition) caused a regression in 4.4.
The xen functions to convert between pages and pfns fail due to an
overflow on systems where a physical address may not fit in an
unsigned long (e.g. x86 32 bit PAE systems). Rework the conversion to
avoid overflow. This should also result in simpler object code.
This bug manifested itself as disk corruption with Linux 4.4 when
using blkfront in a Xen HVM x86 32 bit guest with more than 4 GiB of
memory.
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: <stable@vger.kernel.org> # 4.4+
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
49 lines
1.3 KiB
C
49 lines
1.3 KiB
C
#ifndef _XEN_PAGE_H
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#define _XEN_PAGE_H
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#include <asm/page.h>
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/* The hypercall interface supports only 4KB page */
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#define XEN_PAGE_SHIFT 12
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#define XEN_PAGE_SIZE (_AC(1, UL) << XEN_PAGE_SHIFT)
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#define XEN_PAGE_MASK (~(XEN_PAGE_SIZE-1))
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#define xen_offset_in_page(p) ((unsigned long)(p) & ~XEN_PAGE_MASK)
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/*
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* We assume that PAGE_SIZE is a multiple of XEN_PAGE_SIZE
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* XXX: Add a BUILD_BUG_ON?
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*/
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#define xen_pfn_to_page(xen_pfn) \
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(pfn_to_page((unsigned long)(xen_pfn) >> (PAGE_SHIFT - XEN_PAGE_SHIFT)))
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#define page_to_xen_pfn(page) \
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((page_to_pfn(page)) << (PAGE_SHIFT - XEN_PAGE_SHIFT))
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#define XEN_PFN_PER_PAGE (PAGE_SIZE / XEN_PAGE_SIZE)
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#define XEN_PFN_DOWN(x) ((x) >> XEN_PAGE_SHIFT)
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#define XEN_PFN_UP(x) (((x) + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT)
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#define XEN_PFN_PHYS(x) ((phys_addr_t)(x) << XEN_PAGE_SHIFT)
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#include <asm/xen/page.h>
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/* Return the GFN associated to the first 4KB of the page */
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static inline unsigned long xen_page_to_gfn(struct page *page)
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{
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return pfn_to_gfn(page_to_xen_pfn(page));
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}
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struct xen_memory_region {
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unsigned long start_pfn;
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unsigned long n_pfns;
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};
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#define XEN_EXTRA_MEM_MAX_REGIONS 128 /* == E820MAX */
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extern __initdata
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struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS];
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extern unsigned long xen_released_pages;
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#endif /* _XEN_PAGE_H */
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