Messages in this thread | | | Subject | Re: [RFC PATCH 00/12] Introduce sv48 support without relocable kernel | From | Alex Ghiti <> | Date | Sat, 30 Jan 2021 04:33:20 -0500 |
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Hi Palmer,
On 1/4/21 2:58 PM, Alexandre Ghiti wrote: > This patchset, contrary to the previous versions, allows to have a single > kernel for sv39 and sv48 without being relocatable. > > The idea comes from Arnd Bergmann who suggested to do the same as x86, > that is mapping the kernel to the end of the address space, which allows > the kernel to be linked at the same address for both sv39 and sv48 and > then does not require to be relocated at runtime. > > This is an RFC because I need to at least rebase a few commits and add > documentation. The most interesting patches where I expect feedbacks are > 1/12, 2/12 and 8/12. Note that moving the kernel out of the linear > mapping and sv48 support can be separate patchsets, I share them together > today to show that it works (this patchset is rebased on top of v5.10). > > If we agree about the overall idea, I'll rebase my relocatable patchset > on top of that and then KASLR implementation from Zong will be greatly > simplified since moving the kernel out of the linear mapping will avoid > to copy the kernel physically. > > This implements sv48 support at runtime. The kernel will try to > boot with 4-level page table and will fallback to 3-level if the HW does not > support it. Folding the 4th level into a 3-level page table has almost no > cost at runtime. > > Finally, the user can now ask for sv39 explicitly by using the device-tree > which will reduce memory footprint and reduce the number of memory accesses > in case of TLB miss. > > Alexandre Ghiti (12): > riscv: Move kernel mapping outside of linear mapping > riscv: Protect the kernel linear mapping > riscv: Get rid of compile time logic with MAX_EARLY_MAPPING_SIZE > riscv: Allow to dynamically define VA_BITS > riscv: Simplify MAXPHYSMEM config > riscv: Prepare ptdump for vm layout dynamic addresses > asm-generic: Prepare for riscv use of pud_alloc_one and pud_free > riscv: Implement sv48 support > riscv: Allow user to downgrade to sv39 when hw supports sv48 > riscv: Use pgtable_l4_enabled to output mmu type in cpuinfo > riscv: Explicit comment about user virtual address space size > riscv: Improve virtual kernel memory layout dump > > arch/riscv/Kconfig | 34 +-- > arch/riscv/boot/loader.lds.S | 3 +- > arch/riscv/include/asm/csr.h | 3 +- > arch/riscv/include/asm/fixmap.h | 3 + > arch/riscv/include/asm/page.h | 33 ++- > arch/riscv/include/asm/pgalloc.h | 40 +++ > arch/riscv/include/asm/pgtable-64.h | 104 ++++++- > arch/riscv/include/asm/pgtable.h | 68 +++-- > arch/riscv/include/asm/sparsemem.h | 6 +- > arch/riscv/kernel/cpu.c | 23 +- > arch/riscv/kernel/head.S | 6 +- > arch/riscv/kernel/module.c | 4 +- > arch/riscv/kernel/vmlinux.lds.S | 3 +- > arch/riscv/mm/context.c | 2 +- > arch/riscv/mm/init.c | 376 ++++++++++++++++++++---- > arch/riscv/mm/physaddr.c | 2 +- > arch/riscv/mm/ptdump.c | 56 +++- > drivers/firmware/efi/libstub/efi-stub.c | 2 +- > include/asm-generic/pgalloc.h | 24 +- > include/linux/sizes.h | 3 +- > 20 files changed, 648 insertions(+), 147 deletions(-) >
Any thought about the idea ? Is it going in the right direction ? I have fixed quite a few things since I posted this so don't bother giving this patchset a full review.
Thanks,
Alex
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