From mboxrd@z Thu Jan 1 00:00:00 1970 From: matthias.bgg@gmail.com (Matthias Brugger) Date: Fri, 12 Feb 2016 21:10:29 +0100 Subject: [PATCH v5sub1 0/8] arm64: split linear and kernel mappings In-Reply-To: References: <1454324093-15998-1-git-send-email-ard.biesheuvel@linaro.org> <56BE3645.3030403@gmail.com> Message-ID: <56BE3C35.7070608@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/02/16 20:47, Ard Biesheuvel wrote: > On 12 February 2016 at 20:45, Matthias Brugger wrote: >> Hi Ard, >> >> >> On 01/02/16 11:54, Ard Biesheuvel wrote: >>> >>> At the request of Catalin, this series has been split off from my series >>> 'arm64: implement support for KASLR v4' [1]. This sub-series deals with >>> moving the kernel out of the linear mapping into the vmalloc area. This >>> is a prerequisite for independent physical and virtual randomization of >>> the kernel image. On top of that, considering that these changes allow >>> the linear mapping to start at an arbitrary offset above PAGE_OFFSET, it >>> should be an improvement in itself due to the fact that we can now choose >>> PAGE_OFFSET such that RAM can be mapped using large block sizes. >>> >>> For instance, on my Seattle A0 box, the kernel is loaded 16 MB into the >>> lowest GB of RAM, which means __pa(PAGE_OFFSET) is not 1 GB aligned, and >>> the entire 16 GB of RAM will be mapping using 2 MB blocks. (Similarly, >>> for 64 KB granule kernels, the entire 16 GB of RAM will be mapped using >>> pages since __pa(PAGE_OFFSET) is not 512 MB aligned). With these changes >>> __pa(PAGE_OFFSET) will always be chosen such that it is aligned to a >>> quantity that allows efficient mapping. >>> >>> Note that of the entire KASLR series, this sub-series is the most likely >>> to >>> cause problems, and hence requires the most careful review and testing. >>> This >>> is due to the fact that, with these changes, the invariant __va(__pa(x)) >>> == x >>> no longer holds, and any code that is based on that assumption needs to be >>> updated. >>> >>> Changes since v4: >>> - added Marc's ack to patch #6 >>> - round the kasan zero shadow region around the kernel image to swapper >>> block >>> size (#7) >>> - ensure that we don't clip the kernel image when clipping RAM to the >>> linear >>> region size (#8) >>> >>> Patch #1 allows the low mark of memblocks discovered from the FDT to be >>> overridden by the architecture. >>> >>> Patch #2 enables the huge-vmap generic feature for arm64. This should be >>> an >>> improvement in itself, but the significance for this series is that it >>> allows >>> unmap_kernel_range() to be called on the [__init_begin, __init_end) >>> region, >>> which may be partially mapped using block mappings. >>> >>> Patch #3 introduces KIMAGE_VADDR as a separate, preparatory step towards >>> decoupling the kernel placement from PAGE_OFFSET >>> >>> Patch #4 implements some translation table accessors that operate on >>> statically >>> allocate translation tables before the linear mapping is up. >>> >>> Patch #5 decouples the fixmap initialization from the linear mapping, by >>> using >>> the accessors implemented by patch #4 >>> >>> Patch #6 removes assumptions made my KVM regarding the placement of the >>> kernel >>> image inside the linear mapping. >>> >>> Patch #7 moves the kernel image from the base of the linear mapping to the >>> base >>> of the vmalloc area. The modules area, which sits right below the kernel >>> image, >>> is moved along and is put right before the start of the vmalloc area. >>> >>> Patch #8 decouples PHYS_OFFSET from PAGE_OFFSET, which allows the linear >>> mapping >>> to cover all discovered memory, regardless of where the kernel image is >>> located >>> in it. This effectively allows the kernel to be loaded at any physical >>> address >>> (provided that the correct alignment is used) >>> >>> [1] http://thread.gmane.org/gmane.linux.kernel/2135931 >>> >>> Ard Biesheuvel (8): >>> of/fdt: make memblock minimum physical address arch configurable >>> arm64: add support for ioremap() block mappings >>> arm64: introduce KIMAGE_VADDR as the virtual base of the kernel region >>> arm64: pgtable: implement static [pte|pmd|pud]_offset variants >>> arm64: decouple early fixmap init from linear mapping >>> arm64: kvm: deal with kernel symbols outside of linear mapping >>> arm64: move kernel image to base of vmalloc area >>> arm64: allow kernel Image to be loaded anywhere in physical memory >>> >> >> I bisected linux-next (20160212) with the following error on booting with an >> initramfs: >> Failed to execute /init (error -8) >> request_module: runaway loop modprobe binfmt-464c >> Starting init: /sbin/init exists but couldn't execute it (error -8) >> request_module: runaway loop modprobe binfmt-464c >> Starting init: /bin/sh exists but couldn't execute it (error -8) >> Kernel panic - not syncing: No working init found. Try passing init= >> option to kernel. See Linux Documentation/init.. >> >> I tracked down the error to patch 7 of this series. But I realized that >> patch 7 does not compile, but from patch 8 onwards I observe the error. >> >> I use defconfig with an initramfs.cpio created with buildroot. >> I tested this on my mt8173 eval board, but I suppose this can be reproduced >> easily on other machines as well. >> > > Thanks for the report. Does this help at all? > > http://thread.gmane.org/gmane.linux.ports.arm.kernel/477645 > I applied them on top of linux-next and this fixed the problem. Thanks, Matthias >> Regards, >> Matthias >> >> >>> Documentation/arm64/booting.txt | 20 ++- >>> Documentation/features/vm/huge-vmap/arch-support.txt | 2 +- >>> arch/arm/include/asm/kvm_asm.h | 2 + >>> arch/arm/kvm/arm.c | 8 +- >>> arch/arm64/Kconfig | 1 + >>> arch/arm64/include/asm/boot.h | 6 + >>> arch/arm64/include/asm/kasan.h | 2 +- >>> arch/arm64/include/asm/kernel-pgtable.h | 12 ++ >>> arch/arm64/include/asm/kvm_asm.h | 2 + >>> arch/arm64/include/asm/kvm_host.h | 8 +- >>> arch/arm64/include/asm/memory.h | 44 ++++-- >>> arch/arm64/include/asm/pgtable.h | 23 ++- >>> arch/arm64/kernel/head.S | 8 +- >>> arch/arm64/kernel/image.h | 13 +- >>> arch/arm64/kernel/vmlinux.lds.S | 4 +- >>> arch/arm64/kvm/hyp.S | 6 +- >>> arch/arm64/mm/dump.c | 12 +- >>> arch/arm64/mm/init.c | 123 >>> ++++++++++++++-- >>> arch/arm64/mm/kasan_init.c | 31 +++- >>> arch/arm64/mm/mmu.c | 155 >>> +++++++++++++++----- >>> drivers/of/fdt.c | 5 +- >>> 21 files changed, 378 insertions(+), 109 deletions(-) >>> >>