From 147dd5610c8d1bacb88a6c1dfdaceaf257946ed0 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Thu, 16 Dec 2010 19:11:09 -0800 Subject: 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 Signed-off-by: H. Peter Anvin Tested-by: Yinghai Lu LKML-Reference: <4D0AD3ED.8070607@kernel.org> --- arch/x86/kernel/head_32.S | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel/head_32.S') diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index bcece91dd311..d7cdf5bc1e63 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -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) -- cgit v1.2.3