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    Subject[PATCH 0/9] [REVIEW-REQUEST] [v4] System Calls for Memory Protection Keys
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    I'm resending these because Ingo has said that he'd "love to have
    some high level MM review & ack for these syscall ABI extensions."
    The only changes to the code in months have been in the selftests.
    So, if anyone has been putting off taking a look at these, I'd
    appreciate a look now.

    I also feel compelled to mention this, since I haven't before and
    it gives me confidence that these interfaces are good enough:

    Among other things, this feature was designed to help fix a class
    of bugs in long-running applications where data corruption is
    detected long after it occurs. Today, applications either live
    with the corruption, or eat a huge performance penalty from
    calling mprotect() frequently. The developers of these
    applications are already running *this* *code* and are very eager
    to see this feature merged and picked up in future distributions
    where their customers can use it.

    Other than this message, a good place to start with a review
    is in the pkey(7) manpage, which I've published in HTML form here:

    https://www.sr71.net/~dave/intel/manpages/

    --

    Memory Protection Keys for User pages (pkeys) is a CPU feature
    which will first appear on Skylake Servers, but will also be
    supported on future non-server parts. It provides a mechanism
    for enforcing page-based protections, but without requiring
    modification of the page tables when an application changes
    wishes to change permissions.

    Among other things, this feature was designed to help fix a class
    of bugs in long-running applications where data corruption is
    detected long after it occurs. Applications today either live
    with the corruption, or eat a huge performance penalty from
    calling mprotect() frequently. The developers of these
    applications are already running this code and are very eager to
    see this feature merged and picked up in future distributions
    where their customers can use it.

    Patches to implement execute-only mapping support using pkeys
    were merged in to 4.6. But, to do anything else useful with
    pkeys, an application needs to be able to set the pkey field in
    the PTE (obviously has to be done in-kernel) and make changes to
    the "rights" register (using unprivileged instructions).

    An application also needs to have an an allocator for the keys
    themselves. If two different parts of an application both want
    to protect their data with pkeys, they first need to know which
    key to use for their individual purposes.

    This set introduces 5 system calls, in 3 logical groups:

    1. PTE pkey setting (sys_pkey_mprotect(), patches #1-3)
    2. Key allocation (sys_pkey_alloc() / sys_pkey_free(), patch #4)
    3. Rights register manipulation (sys_pkey_set/get(), patch #5)

    I have manpages written for some of these syscalls, and have
    had multiple rounds of reviews on the manpages list.

    This set is also available here:

    git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-pkeys.git pkeys-v040

    I've written a set of unit tests for these interfaces, which is
    available as the last patch in the series and integrated in to
    kselftests.

    === diffstat ===

    Dave Hansen (9):
    x86, pkeys: add fault handling for PF_PK page fault bit
    mm: implement new pkey_mprotect() system call
    x86, pkeys: make mprotect_key() mask off additional vm_flags
    x86: wire up mprotect_key() system call
    x86, pkeys: allocation/free syscalls
    x86, pkeys: add pkey set/get syscalls
    generic syscalls: wire up memory protection keys syscalls
    pkeys: add details of system call use to Documentation/
    x86, pkeys: add self-tests

    Documentation/x86/protection-keys.txt | 63 +
    arch/alpha/include/uapi/asm/mman.h | 5 +
    arch/mips/include/uapi/asm/mman.h | 5 +
    arch/parisc/include/uapi/asm/mman.h | 5 +
    arch/x86/entry/syscalls/syscall_32.tbl | 5 +
    arch/x86/entry/syscalls/syscall_64.tbl | 5 +
    arch/x86/include/asm/mmu.h | 8 +
    arch/x86/include/asm/mmu_context.h | 25 +-
    arch/x86/include/asm/pgtable.h | 13 +-
    arch/x86/include/asm/pgtable_64.h | 26 +-
    arch/x86/include/asm/pgtable_types.h | 6 -
    arch/x86/include/asm/pkeys.h | 80 +-
    arch/x86/kernel/fpu/xstate.c | 73 +-
    arch/x86/mm/fault.c | 9 +
    arch/x86/mm/pkeys.c | 38 +-
    arch/xtensa/include/uapi/asm/mman.h | 5 +
    include/linux/pkeys.h | 39 +-
    include/linux/syscalls.h | 8 +
    include/uapi/asm-generic/mman-common.h | 5 +
    include/uapi/asm-generic/unistd.h | 12 +-
    mm/mprotect.c | 134 +-
    tools/testing/selftests/x86/Makefile | 3 +-
    tools/testing/selftests/x86/pkey-helpers.h | 191 +++
    tools/testing/selftests/x86/protection_keys.c | 1316 +++++++++++++++++
    24 files changed, 2012 insertions(+), 67 deletions(-)

    === changelog ===

    Changes from v3:
    * added generic syscalls declarations to include/linux/syscalls.h
    to fix arm64 compile issue.

    Changes from v2:
    * selftest updates:
    * formatting changes like what Ingo asked for with MPX
    * actually call WRPKRU in __wrpkru()
    * once __wrpkru() was fixed, revealed a bug in the ptrace
    test where we were testing against the wrong pointer during
    the "baseline" test
    * Man-pages that match this set are here:
    http://marc.info/?l=linux-man&m=146540723525616&w=2

    Changes from v1:
    * updates to alloc/free patch description calling out that
    "in-use" pkeys may still be pkey_free()'d successfully.
    * Fixed a bug in the selftest where the 'flags' argument was
    not passed to pkey_get().
    * Added all syscalls to generic syscalls header
    * Added extra checking to selftests so it doesn't fall over
    when 1G pages are made the hugetlbfs default.

    Cc: linux-api@vger.kernel.org
    Cc: linux-arch@vger.kernel.org
    Cc: linux-mm@kvack.org
    Cc: x86@kernel.org
    Cc: torvalds@linux-foundation.org
    Cc: akpm@linux-foundation.org
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: mgorman@techsingularity.net
    Cc: hughd@google.com
    Cc: viro@zeniv.linux.org.uk

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