[PATCH v3 00/60] arm64: Add support for LPA2 at stage1 and WXN

Ard Biesheuvel
2023-03-07T14:06:49Z

This is a followup to [0], which was a lot smaller. Thanks to Ryan for
feedback and review. This series is independent from Ryan's work on
adding support for LPA2 to KVM - the only potential source of conflict
should be the patch "arm64: kvm: Limit HYP VA and host S2 range to 48
bits when LPA2 is in effect", which could simply be dropped in favour of
the KVM changes to make it support LPA2.

The first ~15 patches of this series rework how the kernel VA space is
organized, so that the vmemmap region does not take up more space than
necessary, and so that most of it can be reclaimed when running a build
capable of 52-bit virtual addressing on hardware that is not. This is
needed because the vmemmap region will take up a substantial part of the
upper VA region that it shares with the kernel, modules and
vmalloc/vmap mappings once we enable LPA2 with 4k pages.

The next ~30 patches rework the early init code, reimplementing most of
the page table and relocation handling in C code. There are several
reasons why this is beneficial:
- we generally prefer C code over asm for these things, and the macros
that currently exist in head.S for creating the kernel pages tables
are a good example why;
- we no longer need to create the kernel mapping in two passes, which
means we can remove the logic that copies parts of the fixmap and the
KAsan shadow from one set of page tables to the other; this is
especially advantageous for KAsan with LPA2, which needs more
elaborate shadow handling across multiple levels, since the KAsan
region cannot be placed on exact pgd_t bouundaries in that case;
- we can read the ID registers and parse command line overrides before
creating the page tables, which simplifies the LPA2 case, as flicking
the global TCR_EL1.DS bit at a later stage would require elaborate
repainting of all page table descriptors, some of which with the MMU
disabled;
- we can use more elaborate logic to create the mappings, which means we
can use more precise mappings for code and data sections even when
using 2 MiB granularity, and this is a prerequisite for running with
WXN.

As part of the ID map changes, we decouple the ID map size from the
kernel VA size, and switch to a 48-bit VA map for all configurations.

The next 18 patches rework the existing LVA support as a CPU feature,
which simplifies some code and gets rid of the vabits_actual variable.
Then, LPA2 support is implemented in the same vein. This requires adding
support for 5 level paging as well, given that LPA2 introduces a new
paging level '-1' when using 4k pages.

Combined with the vmemmap changes at the start of the series, the
resulting LPA2/4k pages configuration will have the exact same VA space
layout as the ordinary 4k/4 levels configuration, and so LPA2 support
can reasonably be enabled by default, as the fallback is seamless on
non-LPA2 hardware.

In the 16k/LPA2 case, the fallback also reduces the number of paging
levels, resulting in a 47-bit VA space. This is based on the assumption
that hybrid LPA2/non-LPA2 16k pages kernels in production use would
prefer not to take the performance hit of 4 level paging to gain only a
single additional bit of VA space. (Note that generic Android kernels
use only 3 levels of paging today.) Bespoke 16k configurations can still
configure 48-bit virtual addressing as before.

Finally, the last two patches enable support for running with the WXN
control enabled. This was previously part of a separate series [1], but
given that the delta is tiny, it is included here as well.

[0] https://lore.kernel.org/all/20221124123932.2648991-1-ardb@kernel.org/
[1] https://lore.kernel.org/all/20221111171201.2088501-1-ardb@kernel.org/

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Kees Cook <keescook@chromium.org>

Anshuman Khandual (2):
arm64/mm: Add FEAT_LPA2 specific TCR_EL1.DS field
arm64/mm: Add FEAT_LPA2 specific ID_AA64MMFR0.TGRAN[2]

Ard Biesheuvel (57):

// KASLR / vmemmap reorg
arm64: kernel: Disable latent_entropy GCC plugin in early C runtime
arm64: mm: Take potential load offset into account when KASLR is off
arm64: mm: get rid of kimage_vaddr global variable
arm64: mm: Move PCI I/O emulation region above the vmemmap region
arm64: mm: Move fixmap region above vmemmap region
arm64: ptdump: Allow VMALLOC_END to be defined at boot
arm64: ptdump: Discover start of vmemmap region at runtime
arm64: vmemmap: Avoid base2 order of struct page size to dimension
region
arm64: mm: Reclaim unused vmemmap region for vmalloc use
arm64: kaslr: Adjust randomization range dynamically
arm64: kaslr: drop special case for ThunderX in kaslr_requires_kpti()
arm64: kvm: honour 'nokaslr' command line option for the HYP VA space

// Reimplement page table creation code in C
arm64: kernel: Manage absolute relocations in code built under pi/
arm64: kernel: Don't rely on objcopy to make code under pi/ __init
arm64: head: move relocation handling to C code
arm64: idreg-override: Omit non-NULL checks for override pointer
arm64: idreg-override: Prepare for place relative reloc patching
arm64: idreg-override: Avoid parameq() and parameqn()
arm64: idreg-override: avoid strlen() to check for empty strings
arm64: idreg-override: Avoid sprintf() for simple string concatenation
arm64: idreg-override: Avoid kstrtou64() to parse a single hex digit
arm64: idreg-override: Move to early mini C runtime
arm64: kernel: Remove early fdt remap code
arm64: head: Clear BSS and the kernel page tables in one go
arm64: Move feature overrides into the BSS section
arm64: head: Run feature override detection before mapping the kernel
arm64: head: move dynamic shadow call stack patching into early C
runtime
arm64: kaslr: Use feature override instead of parsing the cmdline
again
arm64: idreg-override: Create a pseudo feature for rodata=off
arm64: Add helpers to probe local CPU for PAC/BTI/E0PD support
arm64: head: allocate more pages for the kernel mapping
arm64: head: move memstart_offset_seed handling to C code
arm64: head: Move early kernel mapping routines into C code
arm64: mm: Use 48-bit virtual addressing for the permanent ID map
arm64: pgtable: Decouple PGDIR size macros from PGD/PUD/PMD levels
arm64: kernel: Create initial ID map from C code
arm64: mm: avoid fixmap for early swapper_pg_dir updates
arm64: mm: omit redundant remap of kernel image
arm64: Revert "mm: provide idmap pointer to cpu_replace_ttbr1()"

// Implement LPA2 support
arm64: mm: Handle LVA support as a CPU feature
arm64: mm: Add feature override support for LVA
arm64: mm: Wire up TCR.DS bit to PTE shareability fields
arm64: mm: Add LPA2 support to phys<->pte conversion routines
arm64: mm: Add definitions to support 5 levels of paging
arm64: mm: add LPA2 and 5 level paging support to G-to-nG conversion
arm64: Enable LPA2 at boot if supported by the system
arm64: mm: Add 5 level paging support to fixmap and swapper handling
arm64: kasan: Reduce minimum shadow alignment and enable 5 level
paging
arm64: mm: Add support for folding PUDs at runtime
arm64: ptdump: Disregard unaddressable VA space
arm64: ptdump: Deal with translation levels folded at runtime
arm64: kvm: avoid CONFIG_PGTABLE_LEVELS for runtime levels
arm64: kvm: Limit HYP VA and host S2 range to 48 bits when LPA2 is in
effect
arm64: Enable 52-bit virtual addressing for 4k and 16k granule configs
arm64: defconfig: Enable LPA2 support

// Allow WXN control to be enabled at boot
mm: add arch hook to validate mmap() prot flags
arm64: mm: add support for WXN memory translation attribute

Marc Zyngier (1):
arm64: Turn kaslr_feature_override into a generic SW feature override

arch/arm64/Kconfig | 34 +-
arch/arm64/configs/defconfig | 2 +-
arch/arm64/include/asm/assembler.h | 55 +--
arch/arm64/include/asm/cpufeature.h | 102 +++++
arch/arm64/include/asm/fixmap.h | 1 +
arch/arm64/include/asm/kasan.h | 2 -
arch/arm64/include/asm/kernel-pgtable.h | 104 ++---
arch/arm64/include/asm/memory.h | 50 +--
arch/arm64/include/asm/mman.h | 36 ++
arch/arm64/include/asm/mmu.h | 26 +-
arch/arm64/include/asm/mmu_context.h | 49 ++-
arch/arm64/include/asm/pgalloc.h | 53 ++-
arch/arm64/include/asm/pgtable-hwdef.h | 33 +-
arch/arm64/include/asm/pgtable-prot.h | 18 +-
arch/arm64/include/asm/pgtable-types.h | 6 +
arch/arm64/include/asm/pgtable.h | 229 +++++++++-
arch/arm64/include/asm/scs.h | 34 +-
arch/arm64/include/asm/setup.h | 3 -
arch/arm64/include/asm/sysreg.h | 2 +
arch/arm64/include/asm/tlb.h | 3 +-
arch/arm64/kernel/Makefile | 7 +-
arch/arm64/kernel/cpu_errata.c | 2 +-
arch/arm64/kernel/cpufeature.c | 90 ++--
arch/arm64/kernel/head.S | 465 ++------------------
arch/arm64/kernel/idreg-override.c | 322 --------------
arch/arm64/kernel/image-vars.h | 32 ++
arch/arm64/kernel/kaslr.c | 4 +-
arch/arm64/kernel/module.c | 2 +-
arch/arm64/kernel/pi/Makefile | 28 +-
arch/arm64/kernel/pi/idreg-override.c | 396 +++++++++++++++++
arch/arm64/kernel/pi/kaslr_early.c | 78 +---
arch/arm64/kernel/pi/map_kernel.c | 284 ++++++++++++
arch/arm64/kernel/pi/map_range.c | 104 +++++
arch/arm64/kernel/{ => pi}/patch-scs.c | 36 +-
arch/arm64/kernel/pi/pi.h | 30 ++
arch/arm64/kernel/pi/relacheck.c | 130 ++++++
arch/arm64/kernel/pi/relocate.c | 64 +++
arch/arm64/kernel/setup.c | 22 -
arch/arm64/kernel/sleep.S | 3 -
arch/arm64/kernel/suspend.c | 2 +-
arch/arm64/kernel/vmlinux.lds.S | 14 +-
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 2 +
arch/arm64/kvm/mmu.c | 22 +-
arch/arm64/kvm/va_layout.c | 10 +-
arch/arm64/mm/init.c | 2 +-
arch/arm64/mm/kasan_init.c | 154 +++++--
arch/arm64/mm/mmap.c | 4 +
arch/arm64/mm/mmu.c | 268 ++++++-----
arch/arm64/mm/pgd.c | 17 +-
arch/arm64/mm/proc.S | 106 ++++-
arch/arm64/mm/ptdump.c | 43 +-
arch/arm64/tools/cpucaps | 1 +
include/linux/mman.h | 15 +
mm/mmap.c | 3 +
54 files changed, 2259 insertions(+), 1345 deletions(-)
delete mode 100644 arch/arm64/kernel/idreg-override.c
create mode 100644 arch/arm64/kernel/pi/idreg-override.c
create mode 100644 arch/arm64/kernel/pi/map_kernel.c
create mode 100644 arch/arm64/kernel/pi/map_range.c
rename arch/arm64/kernel/{ => pi}/patch-scs.c (89%)
create mode 100644 arch/arm64/kernel/pi/pi.h
create mode 100644 arch/arm64/kernel/pi/relacheck.c
create mode 100644 arch/arm64/kernel/pi/relocate.c

--
2.39.2