Eric Lee / smarc-fsl-linux-kernel

07 Jun, 2011

1 commit

  • 5cec93c21   x86-64: Emulate legacy vsyscalls ... Browse Code »

    There's a fair amount of code in the vsyscall page. It contains
    a syscall instruction (in the gettimeofday fallback) and who
    knows what will happen if an exploit jumps into the middle of
    some other code.

    Reduce the risk by replacing the vsyscalls with short magic
    incantations that cause the kernel to emulate the real
    vsyscalls. These incantations are useless if entered in the
    middle.

    This causes vsyscalls to be a little more expensive than real
    syscalls. Fortunately sensible programs don't use them.
    The only exception is time() which is still called by glibc
    through the vsyscall - but calling time() millions of times
    per second is not sensible. glibc has this fixed in the
    development tree.

    This patch is not perfect: the vread_tsc and vread_hpet
    functions are still at a fixed address. Fixing that might
    involve making alternative patching work in the vDSO.

    Signed-off-by: Andy Lutomirski
    Acked-by: Linus Torvalds
    Cc: Jesper Juhl
    Cc: Borislav Petkov
    Cc: Arjan van de Ven
    Cc: Jan Beulich
    Cc: richard -rw- weinberger
    Cc: Mikael Pettersson
    Cc: Andi Kleen
    Cc: Brian Gerst
    Cc: Louis Rilling
    Cc: Valdis.Kletnieks@vt.edu
    Cc: pageexec@freemail.hu
    Link: http://lkml.kernel.org/r/e64e1b3c64858820d12c48fa739efbd1485e79d5.1307292171.git.luto@mit.edu
    [ Removed the CONFIG option - it's simpler to just do it unconditionally. Tidied up the code as well. ]
    Signed-off-by: Ingo Molnar

    Andy Lutomirski
     

20 Apr, 2009

1 commit

17 Jul, 2007

2 commits

  • cf99abace   make seccomp zerocost in schedule ... Browse Code »

    This follows a suggestion from Chuck Ebbert on how to make seccomp
    absolutely zerocost in schedule too. The only remaining footprint of
    seccomp is in terms of the bzImage size that becomes a few bytes (perhaps
    even a few kbytes) larger, measure it if you care in the embedded.

    Signed-off-by: Andrea Arcangeli
    Cc: Andi Kleen
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrea Arcangeli
     
  • 1d9d02fee   move seccomp from /proc to a prctl ... Browse Code »

    This reduces the memory footprint and it enforces that only the current
    task can enable seccomp on itself (this is a requirement for a
    strightforward [modulo preempt ;) ] TIF_NOTSC implementation).

    Signed-off-by: Andrea Arcangeli
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrea Arcangeli
     

26 Apr, 2006

1 commit

09 Jan, 2006

1 commit

  • a13656470   [PATCH] remove gcc-2 checks ... Browse Code »

    Remove various things which were checking for gcc-1.x and gcc-2.x compilers.

    From: Adrian Bunk

    Some documentation updates and removes some code paths for gcc < 3.2.

    Acked-by: Russell King
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrew Morton
     

28 Jun, 2005

1 commit

  • ffaa8bd6c   [PATCH] seccomp: tsc disable ... Browse Code »

    I believe at least for seccomp it's worth to turn off the tsc, not just for
    HT but for the L2 cache too. So it's up to you, either you turn it off
    completely (which isn't very nice IMHO) or I recommend to apply this below
    patch.

    This has been tested successfully on x86-64 against current cogito
    repository (i686 compiles so I didn't bother testing ;). People selling
    the cpu through cpushare may appreciate this bit for a peace of mind.

    There's no way to get any timing info anymore with this applied
    (gettimeofday is forbidden of course). The seccomp environment is
    completely deterministic so it can't be allowed to get timing info, it has
    to be deterministic so in the future I can enable a computing mode that
    does a parallel computing for each task with server side transparent
    checkpointing and verification that the output is the same from all the 2/3
    seller computers for each task, without the buyer even noticing (for now
    the verification is left to the buyer client side and there's no
    checkpointing, since that would require more kernel changes to track the
    dirty bits but it'll be easy to extend once the basic mode is finished).

    Eliminating a cold-cache read of the cr4 global variable will save one
    cacheline during the tlb flush while making the code per-cpu-safe at the
    same time. Thanks to Mikael Pettersson for noticing the tlb flush wasn't
    per-cpu-safe.

    The global tlb flush can run from irq (IPI calling do_flush_tlb_all) but
    it'll be transparent to the switch_to code since the IPI won't make any
    change to the cr4 contents from the point of view of the interrupted code
    and since it's now all per-cpu stuff, it will not race. So no need to
    disable irqs in switch_to slow path.

    Signed-off-by: Andrea Arcangeli
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrea Arcangeli
     

17 Apr, 2005

1 commit

  • 1da177e4c   Linux-2.6.12-rc2 ... Browse Code »

    Initial git repository build. I'm not bothering with the full history,
    even though we have it. We can create a separate "historical" git
    archive of that later if we want to, and in the meantime it's about
    3.2GB when imported into git - space that would just make the early
    git days unnecessarily complicated, when we don't have a lot of good
    infrastructure for it.

    Let it rip!

    Linus Torvalds