[v2,00/20] Permission Overlay Extension

Message

Joey Gouly Oct. 27, 2023, 6:08 p.m. UTC

Hello everyone,

This series implements the Permission Overlay Extension introduced in 2022
VMSA enhancements [1]. It is based on v6.6-rc3.

Changes since v1[2]:
	# Added Kconfig option
	# Added KVM support
	# Move VM_PKEY* defines into arch/
	# Add isb() for POR_EL0 context switch
	# Added hwcap test, get-reg-list-test, signal frame handling test

ptrace support is missing, I will add that for v3.

The Permission Overlay Extension allows to constrain permissions on memory
regions. This can be used from userspace (EL0) without a system call or TLB
invalidation.

POE is used to implement the Memory Protection Keys [3] Linux syscall.

The first few patches add the basic framework, then the PKEYS interface is
implemented, and then the selftests are made to work on arm64.

There was discussion about what the 'default' protection key value should be,
I used disallow-all (apart from pkey 0), which matches what x86 does.

I have tested the modified protection_keys test on x86_64 [5], but not PPC.
I haven't build tested the x86/ppc changes, will work on getting at least
an x86 build environment working.

Thanks,
Joey

[1] https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/arm-a-profile-architecture-2022
[2] https://lore.kernel.org/linux-arm-kernel/[e-mail]/
[3] Documentation/core-api/protection-keys.rst
[4] https://lore.kernel.org/linux-arm-kernel/[e-mail]/#t
[5] test_ptrace_modifies_pkru asserts for me on a Ubuntu 5.4 kernel, but does so before my changes as well

Joey Gouly (24):
  arm64/sysreg: add system register POR_EL{0,1}
  arm64/sysreg: update CPACR_EL1 register
  arm64: cpufeature: add Permission Overlay Extension cpucap
  arm64: disable trapping of POR_EL0 to EL2
  arm64: context switch POR_EL0 register
  KVM: arm64: Save/restore POE registers
  arm64: enable the Permission Overlay Extension for EL0
  arm64: add POIndex defines
  arm64: define VM_PKEY_BIT* for arm64
  arm64: mask out POIndex when modifying a PTE
  arm64: enable ARCH_HAS_PKEYS on arm64
  arm64: handle PKEY/POE faults
  arm64: stop using generic mm_hooks.h
  arm64: implement PKEYS support
  arm64: add POE signal support
  arm64: enable PKEY support for CPUs with S1POE
  arm64: enable POE and PIE to coexist
  kselftest/arm64: move get_header()
  selftests: mm: move fpregs printing
  selftests: mm: make protection_keys test work on arm64
  kselftest/arm64: add HWCAP test for FEAT_S1POE
  kselftest/arm64: parse POE_MAGIC in a signal frame
  kselftest/arm64: Add test case for POR_EL0 signal frame records
  KVM: selftests: get-reg-list: add Permission Overlay registers

 Documentation/arch/arm64/elf_hwcaps.rst       |   3 +
 arch/arm64/Kconfig                            |  18 +++
 arch/arm64/include/asm/cpufeature.h           |   6 +
 arch/arm64/include/asm/el2_setup.h            |  10 +-
 arch/arm64/include/asm/hwcap.h                |   1 +
 arch/arm64/include/asm/kvm_arm.h              |   4 +-
 arch/arm64/include/asm/kvm_host.h             |   4 +
 arch/arm64/include/asm/mman.h                 |   8 +-
 arch/arm64/include/asm/mmu.h                  |   2 +
 arch/arm64/include/asm/mmu_context.h          |  51 ++++++-
 arch/arm64/include/asm/page.h                 |  10 ++
 arch/arm64/include/asm/pgtable-hwdef.h        |  10 ++
 arch/arm64/include/asm/pgtable-prot.h         |   8 +-
 arch/arm64/include/asm/pgtable.h              |  26 +++-
 arch/arm64/include/asm/pkeys.h                | 110 ++++++++++++++
 arch/arm64/include/asm/por.h                  |  33 +++++
 arch/arm64/include/asm/processor.h            |   1 +
 arch/arm64/include/asm/sysreg.h               |  16 ++
 arch/arm64/include/asm/traps.h                |   1 +
 arch/arm64/include/uapi/asm/hwcap.h           |   1 +
 arch/arm64/include/uapi/asm/sigcontext.h      |   7 +
 arch/arm64/kernel/cpufeature.c                |  23 +++
 arch/arm64/kernel/cpuinfo.c                   |   1 +
 arch/arm64/kernel/process.c                   |  19 +++
 arch/arm64/kernel/signal.c                    |  51 +++++++
 arch/arm64/kernel/traps.c                     |  12 +-
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h    |  10 ++
 arch/arm64/kvm/sys_regs.c                     |   2 +
 arch/arm64/mm/fault.c                         |  44 +++++-
 arch/arm64/mm/mmap.c                          |   9 ++
 arch/arm64/mm/mmu.c                           |  40 +++++
 arch/arm64/tools/cpucaps                      |   1 +
 arch/arm64/tools/sysreg                       |  15 +-
 arch/powerpc/include/asm/page.h               |  11 ++
 arch/x86/include/asm/page.h                   |  10 ++
 fs/proc/task_mmu.c                            |   2 +
 include/linux/mm.h                            |  13 --
 tools/testing/selftests/arm64/abi/hwcap.c     |  13 ++
 .../testing/selftests/arm64/signal/.gitignore |   1 +
 .../arm64/signal/testcases/poe_siginfo.c      |  86 +++++++++++
 .../arm64/signal/testcases/testcases.c        |  27 +---
 .../arm64/signal/testcases/testcases.h        |  28 +++-
 .../selftests/kvm/aarch64/get-reg-list.c      |  14 ++
 tools/testing/selftests/mm/Makefile           |   2 +-
 tools/testing/selftests/mm/pkey-arm64.h       | 138 ++++++++++++++++++
 tools/testing/selftests/mm/pkey-helpers.h     |   8 +
 tools/testing/selftests/mm/pkey-powerpc.h     |   3 +
 tools/testing/selftests/mm/pkey-x86.h         |   4 +
 tools/testing/selftests/mm/protection_keys.c  |  29 ++--
 49 files changed, 880 insertions(+), 66 deletions(-)
 create mode 100644 arch/arm64/include/asm/pkeys.h
 create mode 100644 arch/arm64/include/asm/por.h
 create mode 100644 tools/testing/selftests/arm64/signal/testcases/poe_siginfo.c
 create mode 100644 tools/testing/selftests/mm/pkey-arm64.h