Linear Address Masking[1] (LAM) modifies the checking that is applied to
64-bit linear addresses, allowing software to use of the untranslated
address bits for metadata.

The patchset brings support for LAM for userspace addresses. Only LAM_U57 at
this time.

Please review and consider applying.

git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git lam

v6:
  - Rebased onto v6.0-rc1
  - LAM_U48 excluded from the patchet. Still available in the git tree;
  - Add ARCH_GET_MAX_TAG_BITS (and tests for it);
  - Fix build without CONFIG_DEBUG_VM;
  - Update comments;
  - Reviewed/Tested-by from Alexander;
v5:
  - Do not use switch_mm() in enable_lam_func()
  - Use mb()/READ_ONCE() pair on LAM enabling;
  - Add self-test by Weihong Zhang;
  - Add comments;
v4:
  - Fix untagged_addr() for LAM_U48;
  - Remove no-threads restriction on LAM enabling;
  - Fix mm_struct access from /proc/$PID/arch_status
  - Fix LAM handling in initialize_tlbstate_and_flush()
  - Pack tlb_state better;
  - Comments and commit messages;
v3:
  - Rebased onto v5.19-rc1
  - Per-process enabling;
  - API overhaul (again);
  - Avoid branches and costly computations in the fast path;
  - LAM_U48 is in optional patch.
v2:
  - Rebased onto v5.18-rc1
  - New arch_prctl(2)-based API
  - Expose status of LAM (or other thread features) in
    /proc/$PID/arch_status

[1] ISE, Chapter 10. https://cdrdv2.intel.com/v1/dl/getContent/671368

Kirill A. Shutemov (7):
  x86/mm: Fix CR3_ADDR_MASK
  x86: CPUID and CR3/CR4 flags for Linear Address Masking
  mm: Pass down mm_struct to untagged_addr()
  x86/mm: Handle LAM on context switch
  x86/uaccess: Provide untagged_addr() and remove tags before address
    check
  x86/mm: Provide arch_prctl() interface for LAM
  x86: Expose untagging mask in /proc/$PID/arch_status

Weihong Zhang (4):
  selftests/x86/lam: Add malloc and tag-bits test cases for
    linear-address masking
  selftests/x86/lam: Add mmap and SYSCALL test cases for linear-address
    masking
  selftests/x86/lam: Add io_uring test cases for linear-address masking
  selftests/x86/lam: Add inherit test cases for linear-address masking

 arch/arm64/include/asm/memory.h               |   4 +-
 arch/arm64/include/asm/signal.h               |   2 +-
 arch/arm64/include/asm/uaccess.h              |   4 +-
 arch/arm64/kernel/hw_breakpoint.c             |   2 +-
 arch/arm64/kernel/traps.c                     |   4 +-
 arch/arm64/mm/fault.c                         |  10 +-
 arch/sparc/include/asm/pgtable_64.h           |   2 +-
 arch/sparc/include/asm/uaccess_64.h           |   2 +
 arch/x86/include/asm/cpufeatures.h            |   1 +
 arch/x86/include/asm/mmu.h                    |   6 +
 arch/x86/include/asm/mmu_context.h            |  45 +
 arch/x86/include/asm/processor-flags.h        |   4 +-
 arch/x86/include/asm/tlbflush.h               |  35 +
 arch/x86/include/asm/uaccess.h                |  42 +-
 arch/x86/include/uapi/asm/prctl.h             |   4 +
 arch/x86/include/uapi/asm/processor-flags.h   |   6 +
 arch/x86/kernel/Makefile                      |   2 +
 arch/x86/kernel/fpu/xstate.c                  |  47 -
 arch/x86/kernel/proc.c                        |  60 ++
 arch/x86/kernel/process.c                     |   3 +
 arch/x86/kernel/process_64.c                  |  65 +-
 arch/x86/mm/tlb.c                             |  43 +-
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |   2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c       |   2 +-
 drivers/gpu/drm/radeon/radeon_gem.c           |   2 +-
 drivers/infiniband/hw/mlx4/mr.c               |   2 +-
 drivers/media/common/videobuf2/frame_vector.c |   2 +-
 drivers/media/v4l2-core/videobuf-dma-contig.c |   2 +-
 .../staging/media/atomisp/pci/hmm/hmm_bo.c    |   2 +-
 drivers/tee/tee_shm.c                         |   2 +-
 drivers/vfio/vfio_iommu_type1.c               |   2 +-
 fs/proc/task_mmu.c                            |   2 +-
 include/linux/mm.h                            |  11 -
 include/linux/uaccess.h                       |  15 +
 lib/strncpy_from_user.c                       |   2 +-
 lib/strnlen_user.c                            |   2 +-
 mm/gup.c                                      |   6 +-
 mm/madvise.c                                  |   2 +-
 mm/mempolicy.c                                |   6 +-
 mm/migrate.c                                  |   2 +-
 mm/mincore.c                                  |   2 +-
 mm/mlock.c                                    |   4 +-
 mm/mmap.c                                     |   2 +-
 mm/mprotect.c                                 |   2 +-
 mm/mremap.c                                   |   2 +-
 mm/msync.c                                    |   2 +-
 tools/testing/selftests/x86/Makefile          |   2 +-
 tools/testing/selftests/x86/lam.c             | 900 ++++++++++++++++++
 virt/kvm/kvm_main.c                           |   2 +-
 49 files changed, 1256 insertions(+), 121 deletions(-)
 create mode 100644 arch/x86/kernel/proc.c
 create mode 100644 tools/testing/selftests/x86/lam.c

-- 
2.35.1

On Mon, Aug 15, 2022 at 07:17:52AM +0300, Kirill A. Shutemov wrote:

> Kirill A. Shutemov (7):
>   x86/mm: Fix CR3_ADDR_MASK
>   x86: CPUID and CR3/CR4 flags for Linear Address Masking
>   mm: Pass down mm_struct to untagged_addr()
>   x86/mm: Handle LAM on context switch
>   x86/uaccess: Provide untagged_addr() and remove tags before address
>     check
>   x86/mm: Provide arch_prctl() interface for LAM
>   x86: Expose untagging mask in /proc/$PID/arch_status

Over-all these are not terrible.. I've replied with a few nits; with
those fixed:

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

On Mon, Aug 15, 2022 at 3:43 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Mon, Aug 15, 2022 at 07:17:52AM +0300, Kirill A. Shutemov wrote:
>
> > Kirill A. Shutemov (7):
> >   x86/mm: Fix CR3_ADDR_MASK
> >   x86: CPUID and CR3/CR4 flags for Linear Address Masking
> >   mm: Pass down mm_struct to untagged_addr()
> >   x86/mm: Handle LAM on context switch
> >   x86/uaccess: Provide untagged_addr() and remove tags before address
> >     check
> >   x86/mm: Provide arch_prctl() interface for LAM
> >   x86: Expose untagging mask in /proc/$PID/arch_status
>
> Over-all these are not terrible.. I've replied with a few nits; with
> those fixed:
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>


The patchset is green on the LLVM buildbot:
https://lab.llvm.org/buildbot/#/builders/169, so my Tested-by: tags
persist.
I'm going to make minor changes to HWASan runtime to accommodate for
the new arch_prctl().


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Alexander Potapenko
Software Engineer

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