63 lines
2.0 KiB
Diff
63 lines
2.0 KiB
Diff
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# Commit b0e55bd49725c7c0183eb18670997b9e5930adac
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# Date 2013-08-05 18:40:23 +0200
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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fix off-by-one mistakes in vm_alloc()
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Also add another pair of assertions to catch eventual further cases of
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incorrect accounting.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by Andrew Cooper <andrew.cooper3@citrix.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/xen/common/vmap.c
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+++ b/xen/common/vmap.c
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@@ -57,8 +57,8 @@ void *vm_alloc(unsigned int nr, unsigned
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{
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struct page_info *pg;
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- ASSERT(!test_bit(vm_low, vm_bitmap));
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- for ( start = vm_low; ; )
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+ ASSERT(vm_low == vm_top || !test_bit(vm_low, vm_bitmap));
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+ for ( start = vm_low; start < vm_top; )
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{
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bit = find_next_bit(vm_bitmap, vm_top, start + 1);
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if ( bit > vm_top )
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@@ -68,12 +68,18 @@ void *vm_alloc(unsigned int nr, unsigned
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* corresponding page a guard one.
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*/
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start = (start + align) & ~(align - 1);
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- if ( start + nr <= bit )
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- break;
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- start = bit < vm_top ?
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- find_next_zero_bit(vm_bitmap, vm_top, bit + 1) : bit;
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- if ( start >= vm_top )
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- break;
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+ if ( bit < vm_top )
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+ {
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+ if ( start + nr < bit )
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+ break;
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+ start = find_next_zero_bit(vm_bitmap, vm_top, bit + 1);
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+ }
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+ else
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+ {
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+ if ( start + nr <= bit )
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+ break;
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+ start = bit;
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+ }
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}
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if ( start < vm_top )
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@@ -115,6 +121,10 @@ void *vm_alloc(unsigned int nr, unsigned
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for ( bit = start; bit < start + nr; ++bit )
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__set_bit(bit, vm_bitmap);
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+ if ( bit < vm_top )
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+ ASSERT(!test_bit(bit, vm_bitmap));
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+ else
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+ ASSERT(bit == vm_top);
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if ( start <= vm_low + 2 )
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vm_low = bit;
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spin_unlock(&vm_lock);
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