From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755370AbcLSNPj (ORCPT ); Mon, 19 Dec 2016 08:15:39 -0500 Received: from mail-lf0-f68.google.com ([209.85.215.68]:36853 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752752AbcLSNPh (ORCPT ); Mon, 19 Dec 2016 08:15:37 -0500 Date: Mon, 19 Dec 2016 16:15:39 +0300 From: Serge Semin To: James Hogan Cc: Matt Redfearn , ralf@linux-mips.org, paul.burton@imgtec.com, rabinv@axis.com, alexander.sverdlin@nokia.com, robh+dt@kernel.org, frowand.list@gmail.com, Sergey.Semin@t-platforms.ru, linux-mips@linux-mips.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 19/21] MIPS memblock: Add print out method of kernel virtual memory layout Message-ID: <20161219131539.GA2101@mobilestation> References: <1482113266-13207-1-git-send-email-fancer.lancer@gmail.com> <1482113266-13207-20-git-send-email-fancer.lancer@gmail.com> <20161219130236.GJ27950@jhogan-linux.le.imgtec.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161219130236.GJ27950@jhogan-linux.le.imgtec.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 19, 2016 at 01:02:37PM +0000, James Hogan wrote: > Hi Matt, > > On Mon, Dec 19, 2016 at 12:04:54PM +0000, Matt Redfearn wrote: > > On 19/12/16 02:07, Serge Semin wrote: > > > It's useful to have some printed map of the kernel virtual memory, > > > at least for debugging purpose. > > > > > > Signed-off-by: Serge Semin > > > --- > > > > @@ -106,6 +107,49 @@ static void __init zone_sizes_init(void) > > > } > > > > > > /* > > > + * Print out kernel memory layout > > > + */ > > > +#define MLK(b, t) b, t, ((t) - (b)) >> 10 > > > +#define MLM(b, t) b, t, ((t) - (b)) >> 20 > > > +#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K) > > > +static void __init mem_print_kmap_info(void) > > > +{ > > > + pr_notice("Virtual kernel memory layout:\n" > > > + " lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n" > > > + " vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n" > > > +#ifdef CONFIG_HIGHMEM > > > + " pkmap : 0x%08lx - 0x%08lx (%4ld MB)\n" > > > +#endif > > > + " fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n" > > > + " .text : 0x%p" " - 0x%p" " (%4td kB)\n" > > > + " .data : 0x%p" " - 0x%p" " (%4td kB)\n" > > > + " .init : 0x%p" " - 0x%p" " (%4td kB)\n", > > > + MLM(PAGE_OFFSET, (unsigned long)high_memory), > > > + MLM(VMALLOC_START, VMALLOC_END), > > > +#ifdef CONFIG_HIGHMEM > > > + MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE)), > > > +#endif > > > + MLK(FIXADDR_START, FIXADDR_TOP), > > > + MLK_ROUNDUP(_text, _etext), > > > + MLK_ROUNDUP(_sdata, _edata), > > > + MLK_ROUNDUP(__init_begin, __init_end)); > > > > Please drop printing the kernel addresses, or at least only do it if > > KASLR is not turned on, otherwise you're removing the advantage of > > KASLR, that critical kernel addresses cannot be determined easily from > > userspace. > > According to Documentation/printk-formats.txt, this is what %pK is for. > Better to use that instead? > > Cheers > James > The function is called from the kernel directly, which is privileged enough to do the printing. So I suppose Matt is right, to hide this prints out unless debug is enabled. Thanks, -Sergey > > > > It may be better to merge the functionality of show_kernel_relocation > > http://lxr.free-electrons.com/source/arch/mips/kernel/relocate.c#L354 > > into this function, but only print it under the same conditions as > > currently, i.e. > > #if defined(CONFIG_DEBUG_KERNEL) && defined(CONFIG_DEBUG_INFO) > > http://lxr.free-electrons.com/source/arch/mips/kernel/setup.c#L530 > > > > Thanks, > > Matt