From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757301AbZCMW76 (ORCPT ); Fri, 13 Mar 2009 18:59:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752635AbZCMW7s (ORCPT ); Fri, 13 Mar 2009 18:59:48 -0400 Received: from gw.goop.org ([64.81.55.164]:36021 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751588AbZCMW7r (ORCPT ); Fri, 13 Mar 2009 18:59:47 -0400 Message-ID: <49BAE55F.40406@goop.org> Date: Fri, 13 Mar 2009 15:59:43 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: "H. Peter Anvin" CC: Yinghai Lu , Ingo Molnar , the arch/x86 maintainers , "Eric W. Biederman" , Linux Kernel Mailing List Subject: Re: [GIT PULL] x86: add brk allocator for very early allocations References: <49B7EDF4.7060904@goop.org> <49B800B8.2040009@kernel.org> <49B9A1CD.5040704@goop.org> <49B9AC7F.9030302@kernel.org> <49BAC1B0.6050107@goop.org> <49BAE210.7090300@zytor.com> In-Reply-To: <49BAE210.7090300@zytor.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > Those references are just the actual reservation of memory. If all > the users of that memory are converted to either brk or bss, > INIT_MAP_BEYOND_END should be removed. If all the users of that > memory aren't converted to brk to bss, we should do so. I just added an adapted Yinghai's patch and added it to push/x86/brk. J The following changes since commit 8131667360004a0b74e4dcadfee8a18d4e2b074f: Jeremy Fitzhardinge (1): x86: allow extend_brk users to reserve brk space are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git push/x86/brk Yinghai Lu (1): x86: put initial_pg_tables into .bss -v4 arch/x86/kernel/head_32.S | 47 ++++++++++++++----------------------- arch/x86/kernel/vmlinux_32.lds.S | 6 +++++ 2 files changed, 24 insertions(+), 29 deletions(-) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 80dc05e..ad7dbbb 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -38,42 +38,30 @@ #define X86_VENDOR_ID new_cpu_data+CPUINFO_x86_vendor_id /* - * This is how much memory *in addition to the memory covered up to - * and including _end* we need mapped initially. - * We need: - * - one bit for each possible page, but only in low memory, which means - * 2^32/4096/8 = 128K worst case (4G/4G split.) + * This is how much memory for page table to and including _end + * we need mapped initially. * - enough space to map all low memory, which means - * (2^32/4096) / 1024 pages (worst case, non PAE) - * (2^32/4096) / 512 + 4 pages (worst case for PAE) - * - a few pages for allocator use before the kernel pagetable has - * been set up + * (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE) + * (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE) * * Modulo rounding, each megabyte assigned here requires a kilobyte of * memory, which is currently unreclaimed. * * This should be a multiple of a page. + * + * KERNEL_IMAGE_SIZE should be greater than pa(_end) + * and small than max_low_pfn, otherwise will waste some page table entries */ LOW_PAGES = (KERNEL_IMAGE_SIZE + PAGE_SIZE_asm - 1)>>PAGE_SHIFT -/* - * To preserve the DMA pool in PAGEALLOC kernels, we'll allocate - * pagetables from above the 16MB DMA limit, so we'll have to set - * up pagetables 16MB more (worst-case): - */ -#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK) -LOW_PAGES = LOW_PAGES + 0x1000000 -#endif - #if PTRS_PER_PMD > 1 PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PMD) + PTRS_PER_PGD #else PAGE_TABLE_SIZE = (LOW_PAGES / PTRS_PER_PGD) #endif -BOOTBITMAP_SIZE = LOW_PAGES / 8 ALLOCATOR_SLOP = 4 -INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_SIZE_asm +INIT_MAP_SIZE = (PAGE_TABLE_SIZE + ALLOCATOR_SLOP) * PAGE_SIZE_asm RESERVE_BRK(pagetables, PAGE_TABLE_SIZE * PAGE_SIZE) @@ -168,10 +156,10 @@ num_subarch_entries = (. - subarch_entries) / 4 /* * Initialize page tables. This creates a PDE and a set of page - * tables, which are located immediately beyond _end. The variable + * tables, which are located immediately beyond __brk_base. The variable * _brk_end is set up to point to the first "safe" location. * Mappings are created both at virtual address 0 (identity mapping) - * and PAGE_OFFSET for up to _end+sizeof(page tables)+INIT_MAP_BEYOND_END. + * and PAGE_OFFSET for up to _end. * * Note that the stack is not yet set up! */ @@ -210,10 +198,9 @@ default_entry: loop 11b /* - * End condition: we must map up to and including INIT_MAP_BEYOND_END - * bytes beyond the end of our own page tables. + * End condition: we must map up to the end. */ - leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp + movl $pa(_end) + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b 1: @@ -243,11 +230,9 @@ page_pde_offset = (__PAGE_OFFSET >> 20); addl $0x1000,%eax loop 11b /* - * End condition: we must map up to and including INIT_MAP_BEYOND_END - * bytes beyond the end of our own page tables; the +0x007 is - * the attribute bits + * End condition: we must map up to end */ - leal (INIT_MAP_BEYOND_END+PTE_IDENT_ATTR)(%edi),%ebp + movl $pa(_end) + PTE_IDENT_ATTR, %ebp cmpl %ebp,%eax jb 10b addl $__PAGE_OFFSET, %edi @@ -638,6 +623,10 @@ swapper_pg_fixmap: .fill 1024,4,0 ENTRY(empty_zero_page) .fill 4096,1,0 + +.section ".bss.extra_page_aligned","wa" + .align PAGE_SIZE_asm + .fill INIT_MAP_SIZE,1,0 /* * This starts the data section. */ diff --git a/arch/x86/kernel/vmlinux_32.lds.S b/arch/x86/kernel/vmlinux_32.lds.S index 4005279..c318dee 100644 --- a/arch/x86/kernel/vmlinux_32.lds.S +++ b/arch/x86/kernel/vmlinux_32.lds.S @@ -210,6 +210,12 @@ SECTIONS DWARF_DEBUG } +/* + * Build-time check on the image size: + */ +ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE), + "kernel image bigger than KERNEL_IMAGE_SIZE") + #ifdef CONFIG_KEXEC /* Link time checks */ #include