From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751372AbbJJCDn (ORCPT ); Fri, 9 Oct 2015 22:03:43 -0400 Received: from mail-pa0-f43.google.com ([209.85.220.43]:34415 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750967AbbJJCDk convert rfc822-to-8bit (ORCPT ); Fri, 9 Oct 2015 22:03:40 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.0 \(3094\)) Subject: Re: [RFC] arm: add relocate initrd support From: yalin wang In-Reply-To: <20151009161033.GA32532@n2100.arm.linux.org.uk> Date: Sat, 10 Oct 2015 10:03:30 +0800 Cc: nico@linaro.org, keescook@chromium.org, robh@kernel.org, stefan@agner.ch, rabin@rab.in, msalter@redhat.com, ard.biesheuvel@linaro.org, will.deacon@arm.com, ssantosh@kernel.org, yamada.m@jp.panasonic.com, sboyd@codeaurora.org, contact@paulk.fr, pavel@ucw.cz, slash.tmp@free.fr, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <42FD0845-9A75-4FEE-BD11-65BA661EC35F@gmail.com> References: <1444406109-28354-1-git-send-email-yalin.wang2010@gmail.com> <20151009161033.GA32532@n2100.arm.linux.org.uk> To: Russell King - ARM Linux X-Mailer: Apple Mail (2.3094) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Oct 10, 2015, at 00:10, Russell King - ARM Linux wrote: > > On Fri, Oct 09, 2015 at 11:55:09PM +0800, yalin wang wrote: >> Add support for initrd on ARM arch, in case >> mem= boot option change the memory size or the initrd are >> not placed in low memory region, we need copy the initrd >> to low memory region. >> >> Signed-off-by: yalin wang >> --- >> arch/arm/include/asm/fixmap.h | 1 + >> arch/arm/kernel/setup.c | 72 +++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 73 insertions(+) >> >> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h >> index 58cfe9f..18ad90f 100644 >> --- a/arch/arm/include/asm/fixmap.h >> +++ b/arch/arm/include/asm/fixmap.h >> @@ -10,6 +10,7 @@ >> >> enum fixed_addresses { >> FIX_EARLYCON_MEM_BASE, >> + FIX_RELOCATE_INITRD, >> __end_of_permanent_fixed_addresses, >> >> FIX_KMAP_BEGIN = __end_of_permanent_fixed_addresses, >> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >> index 20edd34..4260d59 100644 >> --- a/arch/arm/kernel/setup.c >> +++ b/arch/arm/kernel/setup.c >> @@ -811,6 +811,77 @@ static void __init request_standard_resources(const struct machine_desc *mdesc) >> request_resource(&ioport_resource, &lp2); >> } >> >> +#if defined(CONFIG_BLK_DEV_INITRD) && defined(CONFIG_MMU) >> +/* >> + * Relocate initrd if it is not completely within the linear mapping. >> + * This would be the case if mem= cuts out all or part of it >> + * or the initrd are not in low mem region place. >> + */ >> +static void __init relocate_initrd(void) >> +{ >> + phys_addr_t orig_start = __virt_to_phys(initrd_start); >> + phys_addr_t orig_end = __virt_to_phys(initrd_end); > > If initrd_start or initrd_end are outside of the lowmem region, it's > quite possible for these to return incorrect physical addresses. > The generic kernel's idea of using virtual addresses for the initrd > stuff is painfully wrong IMHO. > > The unfortunate thing is that the DT code propagates this stuff: > > initrd_start = (unsigned long)__va(start); > initrd_end = (unsigned long)__va(end); > > and even this can give wrong results for the virtual address when the > physical is outside of lowmem. For addresses outside of lowmem, > __virt_to_phys(__va(start)) is not guaranteed to return 'start'. > > This is why I've said that if we want to support ramdisks outside of > the lowmem mapping, we need to get rid of the initrd_start/initrd_end > virtual addresses. > > I'm sorry, but we need much wider code changes before we can cope with > this. > >> + phys_addr_t ram_end = memblock_end_of_DRAM(); >> + phys_addr_t new_start; >> + phys_addr_t src; >> + unsigned long size, to_free = 0; >> + unsigned long slop, clen, p; >> + void *dest; >> + >> + if (orig_end <= memblock_get_current_limit()) >> + return; >> + >> + /* >> + * Any of the original initrd which overlaps the linear map should >> + * be freed after relocating. > > How does this work? The code in arm_memblock_init() will have already > reserved the physical addresses for the ramdisk: > > memblock_reserve(phys_initrd_start, phys_initrd_size); > > So any new allocation shouldn't overlap the existing ramdisk - unless > this is wrong. > i see, i will send a V2 patch for review . Thanks