From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757214Ab3AONsw (ORCPT ); Tue, 15 Jan 2013 08:48:52 -0500 Received: from smtp.citrix.com ([66.165.176.89]:55519 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756066Ab3AONss (ORCPT ); Tue, 15 Jan 2013 08:48:48 -0500 X-IronPort-AV: E=Sophos;i="4.84,473,1355097600"; d="scan'208";a="3788770" Date: Tue, 15 Jan 2013 13:48:45 +0000 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Yinghai Lu CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "Eric W. Biederman" , Andrew Morton , Borislav Petkov , Jan Kiszka , Jason Wessel , "linux-kernel@vger.kernel.org" , Konrad Rzeszutek Wilk Subject: Re: [PATCH v7u1 10/31] x86, 64bit: Don't set max_pfn_mapped wrong value early on native path In-Reply-To: <1357260531-11115-11-git-send-email-yinghai@kernel.org> Message-ID: References: <1357260531-11115-1-git-send-email-yinghai@kernel.org> <1357260531-11115-11-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 On Fri, 4 Jan 2013, Yinghai Lu wrote: > We are not having max_pfn_mapped set correctly until init_memory_mapping. > > so don't print it initial value for 64bit > > Also need to use KERNEL_IMAGE_SIZE directly for highmap cleanup. > > Signed-off-by: Yinghai Lu > --- > arch/x86/kernel/head64.c | 3 --- > arch/x86/kernel/setup.c | 2 ++ > arch/x86/mm/init_64.c | 6 +++++- > 3 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index a3fc233..7061d8b 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -146,9 +146,6 @@ void __init x86_64_start_kernel(char * real_mode_data) > /* clear bss before set_intr_gate with early_idt_handler */ > clear_bss(); > > - /* XXX - this is wrong... we need to build page tables from scratch */ > - max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT; > - > for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) { > #ifdef CONFIG_EARLY_PRINTK > set_intr_gate(i, &early_idt_handlers[i]); > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 63160c6..04797e78 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -910,8 +910,10 @@ void __init setup_arch(char **cmdline_p) > setup_bios_corruption_check(); > #endif > > +#ifdef CONFIG_X86_32 > printk(KERN_DEBUG "initial memory mapped: [mem 0x00000000-%#010lx]\n", > (max_pfn_mapped< +#endif > > reserve_real_mode(); > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 9c5f2b1..98385a2 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -394,10 +394,14 @@ void __init init_extra_mapping_uc(unsigned long phys, unsigned long size) > void __init cleanup_highmap(void) > { > unsigned long vaddr = __START_KERNEL_map; > - unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT); > + unsigned long vaddr_end = __START_KERNEL_map + KERNEL_IMAGE_SIZE; > unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1; > pmd_t *pmd = level2_kernel_pgt; > > + /* Xen has its own end somehow with abused max_pfn_mapped */ > + if (max_pfn_mapped) > + vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT); If you are going to put a comment like that in the code, could you please at least add some useful details, rather than a generic "somehow"? It doesn't seem very helpful to me or to any other hackers looking at the code. The issue is even described as a comment in the code at the beginning of arch/x86/xen/mmu.c:xen_setup_kernel_pagetable: /* max_pfn_mapped is the last pfn mapped in the initial memory * mappings. Considering that on Xen after the kernel mappings we * have the mappings of some pages that don't exist in pfn space, we * set max_pfn_mapped to the last real pfn mapped. */ Now if max_pfn_mapped is supposed to represent the last pfn mapped in the initial memory mapping, then I think that the way Xen uses max_pfn_mapped is actually correct. The question is: has max_pfn_mapped actually changed meaning? Because if it hasn't I don't see why you need this change. > for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) { > if (pmd_none(*pmd)) > continue; > -- > 1.7.10.4 > > -- > 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/ >