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    Subject[PATCH 0/4] vsyscall tweaks
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    With the new vsyscall emulation code, int 0xcc's behavior depends on
    where it is called from. A few dynamic instrumentation tools cleverly
    copy the instruction out of the vsyscall page and execute it, resulting
    in a segfault. This is nothing new: sysenter would die in a similar way
    (unless the code got lucky). The only examples I know of are pin and
    DynamoRIO -- valgrind is already smart enough not to recompile vsyscalls
    0 and 1 and "smart" enough to crash unconditionally on vsyscall 2. I
    can't test pin because it refuses to run on newfangled things like Linux
    3.0+ (and I don't want to muck with my kernel version to run a program
    that's broken anyway). Patch 1 in this series fixes DynamoRIO in
    limited testing.

    Bug reports against valgrind and DynamoRIO exist, and I haven't managed
    to get permission to post to pin's message board yet.

    The other three patches are minor. Patch 2 removes compile flags that
    are now unnecessary because vsyscall_64.c does not get called in user
    mode. Patch 3 wires up the getcpu syscall on x86-64 as further
    encouragement to stop using the vsyscall. Patch 4 adds a
    feature-removal-schedule.txt entry suggesting that vsyscalls might be
    disabled in some configurations some day.

    x86 maintainers / Linus: feel free to drop any of patches 2-4. I think
    the getcpu syscall should be added, though, since it's rather odd to
    have a "syscall" in the vdso and the vsyscall page that can't be called
    the old-fashioned way.

    Changes from RFC v2:
    - Fix some more int 0xcc references.
    - Add patches 2-4.

    Andy Lutomirski (4):
    x86-64: Allow emulated vsyscalls from user addresses
    x86: Remove unnecessary compile flag tweaks for vsyscall code
    x86-64: Wire up getcpu syscall
    Add vsyscalls to feature-removal-schedule.txt

    Documentation/feature-removal-schedule.txt | 14 +++
    arch/x86/include/asm/irq_vectors.h | 11 ++-
    arch/x86/include/asm/traps.h | 8 ++-
    arch/x86/include/asm/unistd_64.h | 2 +
    arch/x86/kernel/Makefile | 13 ---
    arch/x86/kernel/entry_64.S | 4 +-
    arch/x86/kernel/traps.c | 14 +++-
    arch/x86/kernel/vsyscall_64.c | 131 ++++++++++++++--------------
    arch/x86/kernel/vsyscall_emu_64.S | 6 +-
    9 files changed, 111 insertions(+), 92 deletions(-)

    --
    1.7.6



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