[PATCH v3 00/13] Introduce sv48 support without relocatable kernel

[Alexandre Ghiti]

* Please note notable changes in memory layouts and kasan population *

This patchset 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 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.

Note that kasan region had to be moved to the end of the address space
since its location must be known at compile-time and then be valid for
both sv39 and sv48 (and sv57 that is coming).

Tested on:
  - qemu rv64 sv39: OK
  - qemu rv64 sv48: OK
  - qemu rv64 sv39 + kasan: OK
  - qemu rv64 sv48 + kasan: OK
  - qemu rv32: OK

Changes in v3:
  - Fix SZ_1T, thanks to Atish
  - Fix warning create_pud_mapping, thanks to Atish
  - Fix k210 nommu build, thanks to Atish
  - Fix wrong rebase as noted by Samuel
  - * Downgrade to sv39 is only possible if !KASAN (see commit changelog) *
  - * Move KASAN next to the kernel: virtual layouts changed and kasan population *

Changes in v2:
  - Rebase onto for-next
  - Fix KASAN
  - Fix stack canary
  - Get completely rid of MAXPHYSMEM configs
  - Add documentation

Alexandre Ghiti (13):
  riscv: Move KASAN mapping next to the kernel mapping
  riscv: Split early kasan mapping to prepare sv48 introduction
  riscv: Introduce functions to switch pt_ops
  riscv: Allow to dynamically define VA_BITS
  riscv: Get rid of MAXPHYSMEM configs
  asm-generic: Prepare for riscv use of pud_alloc_one and pud_free
  riscv: Implement sv48 support
  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
  Documentation: riscv: Add sv48 description to VM layout
  riscv: Initialize thread pointer before calling C functions
  riscv: Allow user to downgrade to sv39 when hw supports sv48 if !KASAN

 Documentation/riscv/vm-layout.rst             |  48 ++-
 arch/riscv/Kconfig                            |  37 +-
 arch/riscv/configs/nommu_k210_defconfig       |   1 -
 .../riscv/configs/nommu_k210_sdcard_defconfig |   1 -
 arch/riscv/configs/nommu_virt_defconfig       |   1 -
 arch/riscv/include/asm/csr.h                  |   3 +-
 arch/riscv/include/asm/fixmap.h               |   1
 arch/riscv/include/asm/kasan.h                |  11 +-
 arch/riscv/include/asm/page.h                 |  20 +-
 arch/riscv/include/asm/pgalloc.h              |  40 ++
 arch/riscv/include/asm/pgtable-64.h           | 108 ++++-
 arch/riscv/include/asm/pgtable.h              |  47 +-
 arch/riscv/include/asm/sparsemem.h            |   6 +-
 arch/riscv/kernel/cpu.c                       |  23 +-
 arch/riscv/kernel/head.S                      |   4 +-
 arch/riscv/mm/context.c                       |   4 +-
 arch/riscv/mm/init.c                          | 408 ++++++++++++++----
 arch/riscv/mm/kasan_init.c                    | 250 ++++++++---
 drivers/firmware/efi/libstub/efi-stub.c       |   2
 drivers/pci/controller/pci-xgene.c            |   2 +-
 include/asm-generic/pgalloc.h                 |  24 +-
 include/linux/sizes.h                         |   1
 22 files changed, 833 insertions(+), 209 deletions(-)

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2.32.0