Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755415Ab2KMR05 (ORCPT ); Tue, 13 Nov 2012 12:26:57 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:6295 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753488Ab2KMR0z (ORCPT ); Tue, 13 Nov 2012 12:26:55 -0500 X-IronPort-AV: E=Sophos;i="4.80,768,1344211200"; d="scan'208";a="214367494" Date: Tue, 13 Nov 2012 17:26:20 +0000 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Yinghai Lu CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jacob Shin , Andrew Morton , Stefano Stabellini , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 21/46] x86, mm: setup page table in top-down In-Reply-To: <1352755122-25660-22-git-send-email-yinghai@kernel.org> Message-ID: References: <20121112193044.GA11615@phenom.dumpdata.com> <1352755122-25660-1-git-send-email-yinghai@kernel.org> <1352755122-25660-22-git-send-email-yinghai@kernel.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 16970 Lines: 436 On Mon, 12 Nov 2012, Yinghai Lu wrote: > 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. > > 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. > > Suggested-by: "H. Peter Anvin" > Signed-off-by: Yinghai Lu The changes to alloc_low_page and early_alloc_pgt_buf look OK to me. The changes to init_mem_mapping are a bit iffy but they aren't too unreasonable. Overall the patch is OK even though I would certainly appreciate more comments and better variable names (real_end?), see below. > arch/x86/include/asm/page_types.h | 1 + > arch/x86/include/asm/pgtable.h | 1 + > arch/x86/kernel/setup.c | 3 + > arch/x86/mm/init.c | 210 +++++++++++-------------------------- > arch/x86/mm/init_32.c | 17 +++- > arch/x86/mm/init_64.c | 17 +++- > 6 files changed, 94 insertions(+), 155 deletions(-) > > diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h > index 54c9787..9f6f3e6 100644 > --- a/arch/x86/include/asm/page_types.h > +++ b/arch/x86/include/asm/page_types.h > @@ -45,6 +45,7 @@ extern int devmem_is_allowed(unsigned long pagenr); > > extern unsigned long max_low_pfn_mapped; > extern unsigned long max_pfn_mapped; > +extern unsigned long min_pfn_mapped; > > static inline phys_addr_t get_max_mapped(void) > { > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index dd1a888..6991a3e 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -603,6 +603,7 @@ static inline int pgd_none(pgd_t pgd) > > extern int direct_gbpages; > void init_mem_mapping(void); > +void early_alloc_pgt_buf(void); > > /* local pte updates need not use xchg for locking */ > static inline pte_t native_local_ptep_get_and_clear(pte_t *ptep) > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 94f922a..f7634092 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -124,6 +124,7 @@ > */ > unsigned long max_low_pfn_mapped; > unsigned long max_pfn_mapped; > +unsigned long min_pfn_mapped; > > #ifdef CONFIG_DMI > RESERVE_BRK(dmi_alloc, 65536); > @@ -900,6 +901,8 @@ void __init setup_arch(char **cmdline_p) > > reserve_ibft_region(); > > + early_alloc_pgt_buf(); > + > /* > * Need to conclude brk, before memblock_x86_fill() > * it could use memblock_find_in_range, could overlap with > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index 47a1ba2..76a6e82 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -21,6 +21,21 @@ unsigned long __initdata pgt_buf_start; > unsigned long __meminitdata pgt_buf_end; > unsigned long __meminitdata pgt_buf_top; > > +/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */ > +#define INIT_PGT_BUF_SIZE (5 * PAGE_SIZE) > +RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); > +void __init early_alloc_pgt_buf(void) > +{ > + unsigned long tables = INIT_PGT_BUF_SIZE; > + phys_addr_t base; > + > + base = __pa(extend_brk(tables, PAGE_SIZE)); > + > + pgt_buf_start = base >> PAGE_SHIFT; > + pgt_buf_end = pgt_buf_start; > + pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT); > +} > + > int after_bootmem; > > int direct_gbpages > @@ -228,105 +243,6 @@ static int __meminit split_mem_range(struct map_range *mr, int nr_range, > return nr_range; > } > > -/* > - * First calculate space needed for kernel direct mapping page tables to cover > - * mr[0].start to mr[nr_range - 1].end, while accounting for possible 2M and 1GB > - * pages. Then find enough contiguous space for those page tables. > - */ > -static unsigned long __init calculate_table_space_size(unsigned long start, unsigned long end) > -{ > - int i; > - unsigned long puds = 0, pmds = 0, ptes = 0, tables; > - struct map_range mr[NR_RANGE_MR]; > - int nr_range; > - > - memset(mr, 0, sizeof(mr)); > - nr_range = 0; > - nr_range = split_mem_range(mr, nr_range, start, end); > - > - for (i = 0; i < nr_range; i++) { > - unsigned long range, extra; > - > - range = mr[i].end - mr[i].start; > - puds += (range + PUD_SIZE - 1) >> PUD_SHIFT; > - > - if (mr[i].page_size_mask & (1 << PG_LEVEL_1G)) { > - extra = range - ((range >> PUD_SHIFT) << PUD_SHIFT); > - pmds += (extra + PMD_SIZE - 1) >> PMD_SHIFT; > - } else { > - pmds += (range + PMD_SIZE - 1) >> PMD_SHIFT; > - } > - > - if (mr[i].page_size_mask & (1 << PG_LEVEL_2M)) { > - extra = range - ((range >> PMD_SHIFT) << PMD_SHIFT); > -#ifdef CONFIG_X86_32 > - extra += PMD_SIZE; > -#endif > - ptes += (extra + PAGE_SIZE - 1) >> PAGE_SHIFT; > - } else { > - ptes += (range + PAGE_SIZE - 1) >> PAGE_SHIFT; > - } > - } > - > - tables = roundup(puds * sizeof(pud_t), PAGE_SIZE); > - tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE); > - tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE); > - > -#ifdef CONFIG_X86_32 > - /* for fixmap */ > - tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE); > -#endif > - > - return tables; > -} > - > -static unsigned long __init calculate_all_table_space_size(void) > -{ > - unsigned long start_pfn, end_pfn; > - unsigned long tables; > - int i; > - > - /* the ISA range is always mapped regardless of memory holes */ > - tables = calculate_table_space_size(0, ISA_END_ADDRESS); > - > - for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) { > - u64 start = start_pfn << PAGE_SHIFT; > - u64 end = end_pfn << PAGE_SHIFT; > - > - if (end <= ISA_END_ADDRESS) > - continue; > - > - if (start < ISA_END_ADDRESS) > - start = ISA_END_ADDRESS; > -#ifdef CONFIG_X86_32 > - /* on 32 bit, we only map up to max_low_pfn */ > - if ((start >> PAGE_SHIFT) >= max_low_pfn) > - continue; > - > - if ((end >> PAGE_SHIFT) > max_low_pfn) > - end = max_low_pfn << PAGE_SHIFT; > -#endif > - tables += calculate_table_space_size(start, end); > - } > - > - return tables; > -} > - > -static void __init find_early_table_space(unsigned long start, > - unsigned long good_end, > - unsigned long tables) > -{ > - phys_addr_t base; > - > - base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE); > - if (!base) > - panic("Cannot find space for the kernel page tables"); > - > - pgt_buf_start = base >> PAGE_SHIFT; > - pgt_buf_end = pgt_buf_start; > - pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT); > -} > - > static struct range pfn_mapped[E820_X_MAX]; > static int nr_pfn_mapped; > > @@ -392,17 +308,14 @@ unsigned long __init_refok init_memory_mapping(unsigned long start, > } > > /* > - * Iterate through E820 memory map and create direct mappings for only E820_RAM > - * regions. We cannot simply create direct mappings for all pfns from > - * [0 to max_low_pfn) and [4GB to max_pfn) because of possible memory holes in > - * high addresses that cannot be marked as UC by fixed/variable range MTRRs. > - * Depending on the alignment of E820 ranges, this may possibly result in using > - * smaller size (i.e. 4K instead of 2M or 1G) page tables. > + * this one could take range with hole in it. > */ this comment in particular is not very satisfactory > -static void __init init_range_memory_mapping(unsigned long range_start, > +static unsigned long __init init_range_memory_mapping( > + unsigned long range_start, > unsigned long range_end) > { > unsigned long start_pfn, end_pfn; > + unsigned long mapped_ram_size = 0; > int i; > > for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) { > @@ -422,71 +335,70 @@ static void __init init_range_memory_mapping(unsigned long range_start, > end = range_end; > > init_memory_mapping(start, end); > + > + mapped_ram_size += end - start; > } > + > + return mapped_ram_size; > } > > +/* (PUD_SHIFT-PMD_SHIFT)/2 */ > +#define STEP_SIZE_SHIFT 5 > void __init init_mem_mapping(void) > { > - unsigned long tables, good_end, end; > + unsigned long end, real_end, start, last_start; > + unsigned long step_size; > + unsigned long addr; > + unsigned long mapped_ram_size = 0; > + unsigned long new_mapped_ram_size; > > probe_page_size_mask(); > > - /* > - * Find space for the kernel direct mapping tables. > - * > - * Later we should allocate these tables in the local node of the > - * memory mapped. Unfortunately this is done currently before the > - * nodes are discovered. > - */ > #ifdef CONFIG_X86_64 > end = max_pfn << PAGE_SHIFT; > - good_end = end; > #else > end = max_low_pfn << PAGE_SHIFT; > - good_end = max_pfn_mapped << PAGE_SHIFT; > #endif > - tables = calculate_all_table_space_size(); > - find_early_table_space(0, good_end, tables); > - printk(KERN_DEBUG "kernel direct mapping tables up to %#lx @ [mem %#010lx-%#010lx] prealloc\n", > - end - 1, pgt_buf_start << PAGE_SHIFT, > - (pgt_buf_top << PAGE_SHIFT) - 1); > > - max_pfn_mapped = 0; /* will get exact value next */ > /* the ISA range is always mapped regardless of memory holes */ > init_memory_mapping(0, ISA_END_ADDRESS); > - init_range_memory_mapping(ISA_END_ADDRESS, end); > + > + /* xen has big range in reserved near end of ram, skip it at first */ > + addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE, > + PAGE_SIZE); > + real_end = addr + PMD_SIZE; > + > + /* step_size need to be small so pgt_buf from BRK could cover it */ > + step_size = PMD_SIZE; > + max_pfn_mapped = 0; /* will get exact value next */ > + min_pfn_mapped = real_end >> PAGE_SHIFT; > + last_start = start = real_end; > + while (last_start > ISA_END_ADDRESS) { > + if (last_start > step_size) { > + start = round_down(last_start - 1, step_size); > + if (start < ISA_END_ADDRESS) > + start = ISA_END_ADDRESS; > + } else > + start = ISA_END_ADDRESS; > + new_mapped_ram_size = init_range_memory_mapping(start, > + last_start); > + last_start = start; > + min_pfn_mapped = last_start >> PAGE_SHIFT; > + /* only increase step_size after big range get mapped */ > + if (new_mapped_ram_size > mapped_ram_size) > + step_size <<= STEP_SIZE_SHIFT; > + mapped_ram_size += new_mapped_ram_size; > + } > + > + if (real_end < end) > + init_range_memory_mapping(real_end, end); > + > #ifdef CONFIG_X86_64 > if (max_pfn > max_low_pfn) { > /* can we preseve max_low_pfn ?*/ > max_low_pfn = max_pfn; > } > #endif > - /* > - * Reserve the kernel pagetable pages we used (pgt_buf_start - > - * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top) > - * so that they can be reused for other purposes. > - * > - * On native it just means calling memblock_reserve, on Xen it also > - * means marking RW the pagetable pages that we allocated before > - * but that haven't been used. > - * > - * In fact on xen we mark RO the whole range pgt_buf_start - > - * pgt_buf_top, because we have to make sure that when > - * init_memory_mapping reaches the pagetable pages area, it maps > - * RO all the pagetable pages, including the ones that are beyond > - * pgt_buf_end at that time. > - */ > - if (pgt_buf_end > pgt_buf_start) { > - printk(KERN_DEBUG "kernel direct mapping tables up to %#lx @ [mem %#010lx-%#010lx] final\n", > - end - 1, pgt_buf_start << PAGE_SHIFT, > - (pgt_buf_end << PAGE_SHIFT) - 1); > - x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start), > - PFN_PHYS(pgt_buf_end)); > - } > - > - /* stop the wrong using */ > - pgt_buf_top = 0; > - > early_memtest(0, max_pfn_mapped << PAGE_SHIFT); > } you should say why we don't need to call pagetable_reserve anymore: is it because alloc_low_page is going to reserve each page that it allocates? > diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c > index 27f7fc6..7bb1106 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); > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index fa28e3e..eefaea6 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -316,7 +316,7 @@ void __init cleanup_highmap(void) > > static __ref void *alloc_low_page(unsigned long *phys) > { > - unsigned long pfn = pgt_buf_end++; > + unsigned long pfn; > void *adr; > > if (after_bootmem) { > @@ -326,8 +326,19 @@ static __ref void *alloc_low_page(unsigned long *phys) > return 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 = early_memremap(pfn * PAGE_SIZE, PAGE_SIZE); > clear_page(adr); > -- > 1.7.7 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/