Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932948AbbLXGok (ORCPT ); Thu, 24 Dec 2015 01:44:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42446 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932423AbbLXGoY (ORCPT ); Thu, 24 Dec 2015 01:44:24 -0500 Subject: Re: [PATCH 2/2] kexec: Provide arch_kexec_protect(unprotect)_crashkres() To: Dave Young References: <1450869146-6186-1-git-send-email-xlpang@redhat.com> <1450869146-6186-2-git-send-email-xlpang@redhat.com> <20151224055425.GC3480@dhcp-128-65.nay.redhat.com> <567B8B44.9070807@redhat.com> <20151224061616.GD3480@dhcp-128-65.nay.redhat.com> Cc: akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, vgoyal@redhat.com, Eric Biederman From: Xunlei Pang Message-ID: <567B9444.1050608@redhat.com> Date: Thu, 24 Dec 2015 14:44:20 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151224061616.GD3480@dhcp-128-65.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4052 Lines: 124 On 12/24/2015 at 02:16 PM, Dave Young wrote: > Hi, Xunlei > > On 12/24/15 at 02:05pm, Xunlei Pang wrote: >> On 12/24/2015 at 01:54 PM, Dave Young wrote: >>> Ccing Vivek >>> >>> On 12/23/15 at 07:12pm, Xunlei Pang wrote: >>>> Implement the protection method for the crash kernel memory >>>> reservation for the 64-bit x86 kdump. >>>> >>>> Signed-off-by: Xunlei Pang >>>> --- >>>> Only provided x86_64 implementation, as I've only tested on x86_64 so far. >>>> >>>> arch/x86/kernel/machine_kexec_64.c | 43 ++++++++++++++++++++++++++++++++++++++ >>>> 1 file changed, 43 insertions(+) >>>> >>>> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c >>>> index 819ab3f..a3d289c 100644 >>>> --- a/arch/x86/kernel/machine_kexec_64.c >>>> +++ b/arch/x86/kernel/machine_kexec_64.c >>>> @@ -536,3 +536,46 @@ overflow: >>>> return -ENOEXEC; >>>> } >>>> #endif /* CONFIG_KEXEC_FILE */ >>>> + >>>> +#ifdef CONFIG_KEXEC_CORE >>> The file is only compiled when CONFIG_KEXEC_CORE=y so #ifdef is not necessary >> Yes, indeed. I'll remove this macro and send v2 later. >> >>>> +static int >>>> +kexec_mark_range(unsigned long start, unsigned long end, bool protect) >>>> +{ >>>> + struct page *page; >>>> + unsigned int nr_pages; >>>> + >>>> + if (!start || !end || start >= end) >>>> + return 0; >>>> + >>>> + page = pfn_to_page(start >> PAGE_SHIFT); >>>> + nr_pages = (end + 1 - start) >> PAGE_SHIFT; >>>> + if (protect) >>>> + return set_pages_ro(page, nr_pages); >>>> + else >>>> + return set_pages_rw(page, nr_pages); >>> May use set_memory_ro/rw to avoid converting to *page? >> on x86 it just a wrapper of set_memory_ro/rw, I think both are ok. > Ok, I have no strong opinion on that.. > >>>> +} >>>> + >>>> +static void kexec_mark_crashkres(bool protect) >>>> +{ >>>> + unsigned long control; >>>> + >>>> + kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect); >>>> + >>>> + /* Don't touch the control code page used in crash_kexec().*/ >>>> + control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page)); >>>> + /* Control code page is located in the 2nd page. */ >>>> + control = control + PAGE_SIZE; > Though it works because the control code is less than 1 page, but use the macro > of KEXEC_CONTROL_PAGE_SIZE looks better.. > >>>> + kexec_mark_range(crashk_res.start, control - 1, protect); >>>> + kexec_mark_range(control + PAGE_SIZE, crashk_res.end, protect); >>> X86 kexec will copy the page while kexecing, could you check if we can move >>> that copying to earliyer while kexec loading, maybe machine_kexec_prepare so >>> that we can make a arch-independent implementation. >> For some arch, may use huge tlb directly to do the kernel mapping, >> in such cases, we can't implement this function. So I think it should >> be arch-dependent. > Ok, that's fine. At least moving the x86 control-copying code into arch-related machine_kexec_prepare() should work, and this can omit the special treatment of the control code page. Regards, Xunlei > >> Regards, >> Xunlei >> >>>> +} >>>> + >>>> +void arch_kexec_protect_crashkres(void) >>>> +{ >>>> + kexec_mark_crashkres(true); >>>> +} >>>> + >>>> +void arch_kexec_unprotect_crashkres(void) >>>> +{ >>>> + kexec_mark_crashkres(false); >>>> +} >>>> +#endif >>>> -- >>>> 2.5.0 >>>> >>>> >>>> _______________________________________________ >>>> kexec mailing list >>>> kexec@lists.infradead.org >>>> http://lists.infradead.org/mailman/listinfo/kexec >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec > Thanks > Dave > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec -- 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/