From mboxrd@z Thu Jan 1 00:00:00 1970 From: mawupeng Date: Tue, 24 May 2022 01:11:59 +0000 Subject: Re: [PATCH 0/2] Add support to relocate kernel image to mirrored region Message-Id: <262cab19-0bca-a088-77a5-6a41f475f4a4@huawei.com> List-Id: References: <20220419070150.254377-1-mawupeng1@huawei.com> <7058b8d8-c0cb-108e-0db9-2fdf5fb154cf@huawei.com> <7a1ce182-343a-75f9-5447-f7ca12cb0c36@huawei.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: ardb@kernel.org Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, dvhart@infradead.org, andy@infradead.org, rppt@kernel.org, paulmck@kernel.org, peterz@infradead.org, jroedel@suse.de, songmuchun@bytedance.com, macro@orcam.me.uk, frederic@kernel.org, W_Armin@gmx.de, john.garry@huawei.com, seanjc@google.com, tsbogend@alpha.franken.de, anshuman.khandual@arm.com, chenhuacai@kernel.org, david@redhat.com, gpiccoli@igalia.com, mark.rutland@arm.com, wangkefeng.wang@huawei.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, linux-ia64@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-mm@kvack.org, mawupeng1@huawei.com 在 2022/5/23 22:41, Ard Biesheuvel 写道: > On Mon, 23 May 2022 at 03:18, mawupeng wrote: >> >> >> >> 在 2022/5/20 14:52, Ard Biesheuvel 写道: >>> On Thu, 19 May 2022 at 13:09, mawupeng wrote: >>>> >>>> >>>> >>>> 在 2022/5/7 17:28, mawupeng 写道: >>>>> >>>>> >>>>> 在 2022/5/3 17:58, Ard Biesheuvel 写道: >>>>>> On Tue, 19 Apr 2022 at 08:43, Wupeng Ma wrote: >>>>>>> >>>>>>> From: Ma Wupeng >>>>>>> >>>>>>> Now system image will perfer to be located to mirrored regions both KASLR >>>>>>> on and off. >>>>>>> >>>>>> >>>>>> Hello Ma Wupeng, >>>>>> >>>>>> I wonder if we could simplify this as follows: >>>>>> - ignore the non-KASLR case for now, and rely on the bootloader > load the image into mirrored memory if it exists; >>>>> >>>>> In grub, memory for static image is allocated via the following path: >>>>> >>>>> grub_cmd_linux >>>>> kernel = grub_malloc(filelen) >>>>> kernel_alloc_addr = grub_efi_allocate_any_pages (kernel_alloc_pages) >>>>> grub_memcpy (kernel_addr, kernel, grub_min(filelen, kernel_size)) >>>>> grub_loader_set (grub_linux_boot, grub_linux_unload, 0) >>>>> >>>>> Can we get memory from mirrored region by the following steps: >>>>> 1. get memory map by calling grub_efi_get_memory_map() >>>>> 2. iter all memory map to find a suitable mirrored memory area >>>>> 3. locate kernel image to this area >>>>> >>>>> So, if kaslr is not enabled >>>>> - grub will load kernel into mirrored region >>>>> else >>>>> - arm64-stub.c will relocate kernel image to mirrored region >>>>> >>>>> Is this feasible? >>>> >>>> Is this a feasible proposal to relocate the static kernel image itself >>>> into more reliable memory? >>>> >>> >>> I'm not sure, it all depends on the firmware. >>> >>> When GRUB calls LoadImage(), the firmware will reallocate the image >>> and unpack it there. So it is really the firmware's job to ensure that >>> the image is loaded into a suitable location. >>> >>> I have some code here that implements a EFI based decompressor, and >>> which loads the kernel image into mirrored memory if it exists, >>> without the need to move it again. It could trivially be modified to >>> deal with non-randomized loads as well. >>> >>> But the bottom line is that UEFI should expose the ability to target >>> mirrored memory, hacking around it like this is not a sustainable >>> approach. >> >> Since firmware is responsible for put kernel static image into mirrored >> region and kernel is responsible for relocate this image into mirrored >> region if kaslr is enabled. There is no conflict between these two. >> >> Can we integrate the kernel part(introduce mirrored support to arm64) first? >> > > Yes. If you drop the changes related to fake memmap and rebase, please > resend them after -rc1 is released. Ok, I will drop the changes related to fake memmap and rebase and then resend them after -rc1 is released. Thanks for reviewing. > .