Commit 60ac9821 authored Mar 17, 2009 by H. Peter Anvin

x86-32: tighten the bound on additional memory to map



Impact: Tighten bound to avoid masking errors

The definition of MAPPING_BEYOND_END was excessive; this has a nasty
tendency to mask bugs.  We have learned over time that this kind of
bug hiding can cause some very strange errors.  Therefore, tighten the
bound to only need to map the actual kernel area.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Yinghai Lu <yinghai@kernel.org>

parent b8a22a62

arch/x86/kernel/head_32.S

+2 −1

Original line number	Diff line number	Diff line
		@@ -60,7 +60,8 @@
		#endif

		/* Enough space to fit pagetables for the low memory linear map */
		MAPPING_BEYOND_END = (PAGE_TABLE_SIZE(1 << (32 - PAGE_SHIFT)) * PAGE_SIZE)
		MAPPING_BEYOND_END = \
		PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT

		/*
		* Worst-case size of the kernel mapping we need to make: