Dear x86 maintainers,
the series looks pretty mature now, any chance it can be considered
for upstream?
On Sun, Mar 12, 2023 at 12:26 PM Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> 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 capability can be used for efficient address sanitizers (ASAN)
> implementation and for optimizations in JITs and virtual machines.
>
> 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
>
> v16:
> - Add #include <linux/mmu_context.h> into fs/proc/array.c;
> - Whitespace fix;
> - Add Alexander's Tested-bys;
> v15:
> - Replace static branch in untagged_addr() with alternative;
> - Drop unneeded READ_ONCE();
> - Acks from Peter;
> v14:
> - Rework address range check in get_user() and put_user();
> - Introduce CONFIG_ADDRESS_MASKING;
> - Cache untag masking in per-CPU variable;
> - Reject LAM enabling via PTRACE_ARCH_PRCTL;
> - Fix locking around untagged_addr_remote();
> - Fix typo in MM_CONTEXT_ conversion patch;
> - Fix selftest;
> v13:
> - Fix race between untagged_addr() and LAM enabling:
> + Do not allow to enable LAM after the process spawned the second thread;
> + untagged_addr() untags the address according to rules of the current
> process;
> + untagged_addr_remote() can be used for untagging addresses for foreign
> process. It requires mmap lock for the target process to be taken;
> v12:
> - Rebased onto tip/x86/mm;
> - Drop VM_WARN_ON() that may produce false-positive on race between context
> switch and LAM enabling;
> - Adjust comments explain possible race;
> - User READ_ONCE() in mm_lam_cr3_mask();
> - Do not assume &init_mm == mm in initialize_tlbstate_and_flush();
> - Ack by Andy;
> v11:
> - Move untag_mask to /proc/$PID/status;
> - s/SVM/SVA/g;
> - static inline arch_pgtable_dma_compat() instead of macros;
> - Replace pasid_valid() with mm_valid_pasid();
> - Acks from Ashok and Jacob (forgot to apply from v9);
> v10:
> - Rebased to v6.1-rc1;
> - Add selftest for SVM vs LAM;
> v9:
> - Fix race between LAM enabling and check that KVM memslot address doesn't
> have any tags;
> - Reduce untagged_addr() overhead until the first LAM user;
> - Clarify SVM vs. LAM semantics;
> - Use mmap_lock to serialize LAM enabling;
> v8:
> - Drop redundant smb_mb() in prctl_enable_tagged_addr();
> - Cleanup code around build_cr3();
> - Fix commit messages;
> - Selftests updates;
> - Acked/Reviewed/Tested-bys from Alexander and Peter;
> v7:
> - Drop redundant smb_mb() in prctl_enable_tagged_addr();
> - Cleanup code around build_cr3();
> - Fix commit message;
> - Fix indentation;
> v6:
> - Rebased onto v6.0-rc1
> - LAM_U48 excluded from the patchet. Still available in the git tree;
> - add ARCH_GET_MAX_TAG_BITS;
> - Fix build without CONFIG_DEBUG_VM;
> - Update comments;
> - Reviewed/Tested-by from Alexander;
> v5:
> - Do not use switch_mm() in enable_lam_func()
> - Use mb()/READ_ONCE() pair on LAM enabling;
> - Add self-test by Weihong Zhang;
> - Add comments;
> v4:
> - Fix untagged_addr() for LAM_U48;
> - Remove no-threads restriction on LAM enabling;
> - Fix mm_struct access from /proc/$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/$PID/arch_status
>
> [1] ISE, Chapter 10. https://cdrdv2.intel.com/v1/dl/getContent/671368
>
> Kirill A. Shutemov (12):
> x86/mm: Rework address range check in get_user() and put_user()
> x86: Allow atomic MM_CONTEXT flags setting
> x86: CPUID and CR3/CR4 flags for Linear Address Masking
> x86/mm: Handle LAM on context switch
> mm: Introduce untagged_addr_remote()
> x86/uaccess: Provide untagged_addr() and remove tags before address
> check
> x86/mm: Reduce untagged_addr() overhead for systems without LAM
> x86/mm: Provide arch_prctl() interface for LAM
> mm: Expose untagging mask in /proc/$PID/status
> iommu/sva: Replace pasid_valid() helper with mm_valid_pasid()
> x86/mm/iommu/sva: Make LAM and SVA mutually exclusive
> selftests/x86/lam: Add test cases for LAM vs thread creation
>
> Weihong Zhang (5):
> 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
> selftests/x86/lam: Add ARCH_FORCE_TAGGED_SVA test cases for
> linear-address masking
>
> arch/arm64/include/asm/mmu_context.h | 6 +
> arch/sparc/include/asm/mmu_context_64.h | 6 +
> arch/sparc/include/asm/uaccess_64.h | 2 +
> arch/x86/Kconfig | 11 +
> arch/x86/entry/vsyscall/vsyscall_64.c | 2 +-
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/disabled-features.h | 8 +-
> arch/x86/include/asm/mmu.h | 18 +-
> arch/x86/include/asm/mmu_context.h | 49 +-
> arch/x86/include/asm/processor-flags.h | 2 +
> arch/x86/include/asm/tlbflush.h | 48 +-
> arch/x86/include/asm/uaccess.h | 58 +-
> arch/x86/include/uapi/asm/prctl.h | 5 +
> arch/x86/include/uapi/asm/processor-flags.h | 6 +
> arch/x86/kernel/process.c | 6 +
> arch/x86/kernel/process_64.c | 66 +-
> arch/x86/kernel/traps.c | 6 +-
> arch/x86/lib/getuser.S | 83 +-
> arch/x86/lib/putuser.S | 54 +-
> arch/x86/mm/init.c | 5 +
> arch/x86/mm/tlb.c | 53 +-
> drivers/iommu/iommu-sva.c | 8 +-
> drivers/vfio/vfio_iommu_type1.c | 2 +-
> fs/proc/array.c | 7 +
> fs/proc/task_mmu.c | 9 +-
> include/linux/ioasid.h | 9 -
> include/linux/mm.h | 11 -
> include/linux/mmu_context.h | 14 +
> include/linux/sched/mm.h | 8 +-
> include/linux/uaccess.h | 22 +
> mm/gup.c | 4 +-
> mm/madvise.c | 5 +-
> mm/migrate.c | 11 +-
> tools/testing/selftests/x86/Makefile | 2 +-
> tools/testing/selftests/x86/lam.c | 1241 +++++++++++++++++++
> 35 files changed, 1699 insertions(+), 149 deletions(-)
> create mode 100644 tools/testing/selftests/x86/lam.c
>
> --
> 2.39.2
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
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