From 8d57470d8f859635deffe3919d7d4867b488b85a Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 16 Nov 2012 19:38:58 -0800 Subject: x86, mm: setup page table in top-down Get pgt_buf early from BRK, and use it to map PMD_SIZE from top at first. Then use mapped pages to map more ranges below, and keep looping until all pages get mapped. alloc_low_page will use page from BRK at first, after that buffer is used up, will use memblock to find and reserve pages for page table usage. Introduce min_pfn_mapped to make sure find new pages from mapped ranges, that will be updated when lower pages get mapped. Also add step_size to make sure that don't try to map too big range with limited mapped pages initially, and increase the step_size when we have more mapped pages on hand. We don't need to call pagetable_reserve anymore, reserve work is done in alloc_low_page() directly. At last we can get rid of calculation and find early pgt related code. -v2: update to after fix_xen change, also use MACRO for initial pgt_buf size and add comments with it. -v3: skip big reserved range in memblock.reserved near end. -v4: don't need fix_xen change now. -v5: add changelog about moving about reserving pagetable to alloc_low_page. Suggested-by: "H. Peter Anvin" Signed-off-by: Yinghai Lu Link: http://lkml.kernel.org/r/1353123563-3103-22-git-send-email-yinghai@kernel.org Signed-off-by: H. Peter Anvin --- arch/x86/mm/init_32.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'arch/x86/mm/init_32.c') diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 27f7fc69cf8a..7bb11064a9e1 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -61,11 +61,22 @@ bool __read_mostly __vmalloc_start_set = false; static __init void *alloc_low_page(void) { - unsigned long pfn = pgt_buf_end++; + unsigned long pfn; void *adr; - if (pfn >= pgt_buf_top) - panic("alloc_low_page: ran out of memory"); + if ((pgt_buf_end + 1) >= pgt_buf_top) { + unsigned long ret; + if (min_pfn_mapped >= max_pfn_mapped) + panic("alloc_low_page: ran out of memory"); + ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT, + max_pfn_mapped << PAGE_SHIFT, + PAGE_SIZE, PAGE_SIZE); + if (!ret) + panic("alloc_low_page: can not alloc memory"); + memblock_reserve(ret, PAGE_SIZE); + pfn = ret >> PAGE_SHIFT; + } else + pfn = pgt_buf_end++; adr = __va(pfn * PAGE_SIZE); clear_page(adr); -- cgit v1.2.3