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x86-32: Make sure we can map all of lowmem if we need to 

A relocatable kernel can be anywhere in lowmem -- and in the case of a
kdump kernel, is likely to be fairly high.  Since the early page
tables map everything from address zero up we need to make sure we
allocate enough brk that we can map all of lowmem if we need to.

Reported-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4D0AD3ED.8070607@kernel.org>
This commit is contained in:
H. Peter Anvin 2010-12-16 19:11:09 -08:00
parent 7f99d946e7
commit 147dd5610c
2 changed files with 8 additions and 6 deletions
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2
arch/x86/boot/compressed/misc.c
View File

@ -355,7 +355,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap,
if (heap > 0x3fffffffffffUL)
error("Destination address too large");
#else
if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
error("Destination address too large");
#endif
#ifndef CONFIG_RELOCATABLE

12
arch/x86/kernel/head_32.S
View File

@ -60,16 +60,18 @@
#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
#endif
/* Number of possible pages in the lowmem region */
LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT)
/* Enough space to fit pagetables for the low memory linear map */
MAPPING_BEYOND_END = \
PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT
MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
/*
* Worst-case size of the kernel mapping we need to make:
* the worst-case size of the kernel itself, plus the extra we need
* to map for the linear map.
* a relocatable kernel can live anywhere in lowmem, so we need to be able
* to map all of lowmem.
*/
KERNEL_PAGES = (KERNEL_IMAGE_SIZE + MAPPING_BEYOND_END)>>PAGE_SHIFT
KERNEL_PAGES = LOWMEM_PAGES
INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE_asm
RESERVE_BRK(pagetables, INIT_MAP_SIZE)