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    Subject[PATCH 3.12 15/58] x86/entry/compat: Add missing CLAC to entry_INT80_32
    Date
    From: Andy Lutomirski <luto@kernel.org>

    3.12-stable review patch. If anyone has any objections, please let me know.

    ===============

    commit 3d44d51bd339766f0178f0cf2e8d048b4a4872aa upstream.

    This doesn't seem to fix a regression -- I don't think the CLAC was
    ever there.

    I double-checked in a debugger: entries through the int80 gate do
    not automatically clear AC.

    Stable maintainers: I can provide a backport to 4.3 and earlier if
    needed. This needs to be backported all the way to 3.10.

    Reported-by: Brian Gerst <brgerst@gmail.com>
    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Fixes: 63bcff2a307b ("x86, smap: Add STAC and CLAC instructions to control user space access")
    Link: http://lkml.kernel.org/r/b02b7e71ae54074be01fc171cbd4b72517055c0e.1456345086.git.luto@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    [ kamal: backport to 3.10 through 3.19-stable: file rename; context ]
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    ---
    arch/x86/ia32/ia32entry.S | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
    index 92a2e9333620..b74ac9c5710b 100644
    --- a/arch/x86/ia32/ia32entry.S
    +++ b/arch/x86/ia32/ia32entry.S
    @@ -422,6 +422,7 @@ ENTRY(ia32_syscall)
    /*CFI_REL_OFFSET cs,CS-RIP*/
    CFI_REL_OFFSET rip,RIP-RIP
    PARAVIRT_ADJUST_EXCEPTION_FRAME
    + ASM_CLAC /* Do this early to minimize exposure */
    SWAPGS
    /*
    * No need to follow this irqs on/off section: the syscall
    --
    2.7.3
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