Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 147dd561 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

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: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Tested-by: default avatarYinghai Lu <yinghai@kernel.org>
LKML-Reference: <4D0AD3ED.8070607@kernel.org>
parent 7f99d946

arch/x86/boot/compressed/misc.c

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/head_32.S

+7 −5
Original line number Diff line number Diff line
@@ -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)