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    Subject[PATCH 4.4 037/107] x86/mm: Factor out LDT init from context init
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dave Hansen <dave.hansen@linux.intel.com>

    commit 39a0526fb3f7d93433d146304278477eb463f8af upstream

    The arch-specific mm_context_t is a great place to put
    protection-key allocation state.

    But, we need to initialize the allocation state because pkey 0 is
    always "allocated". All of the runtime initialization of
    mm_context_t is done in *_ldt() manipulation functions. This
    renames the existing LDT functions like this:

    init_new_context() -> init_new_context_ldt()
    destroy_context() -> destroy_context_ldt()

    and makes init_new_context() and destroy_context() available for
    generic use.

    Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
    Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave@sr71.net>
    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: Rik van Riel <riel@redhat.com>
    Cc: linux-mm@kvack.org
    Link: http://lkml.kernel.org/r/20160212210234.DB34FCC5@viggo.jf.intel.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
    Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
    Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
    Reviewed-by: Bo Gan <ganb@vmware.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---

    arch/x86/include/asm/mmu_context.h | 21 ++++++++++++++++-----
    arch/x86/kernel/ldt.c | 4 ++--
    2 files changed, 18 insertions(+), 7 deletions(-)

    --- a/arch/x86/include/asm/mmu_context.h
    +++ b/arch/x86/include/asm/mmu_context.h
    @@ -52,15 +52,15 @@ struct ldt_struct {
    /*
    * Used for LDT copy/destruction.
    */
    -int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
    -void destroy_context(struct mm_struct *mm);
    +int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm);
    +void destroy_context_ldt(struct mm_struct *mm);
    #else /* CONFIG_MODIFY_LDT_SYSCALL */
    -static inline int init_new_context(struct task_struct *tsk,
    - struct mm_struct *mm)
    +static inline int init_new_context_ldt(struct task_struct *tsk,
    + struct mm_struct *mm)
    {
    return 0;
    }
    -static inline void destroy_context(struct mm_struct *mm) {}
    +static inline void destroy_context_ldt(struct mm_struct *mm) {}
    #endif

    static inline void load_mm_ldt(struct mm_struct *mm)
    @@ -102,6 +102,17 @@ static inline void enter_lazy_tlb(struct
    this_cpu_write(cpu_tlbstate.state, TLBSTATE_LAZY);
    }

    +static inline int init_new_context(struct task_struct *tsk,
    + struct mm_struct *mm)
    +{
    + init_new_context_ldt(tsk, mm);
    + return 0;
    +}
    +static inline void destroy_context(struct mm_struct *mm)
    +{
    + destroy_context_ldt(mm);
    +}
    +
    extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
    struct task_struct *tsk);

    --- a/arch/x86/kernel/ldt.c
    +++ b/arch/x86/kernel/ldt.c
    @@ -119,7 +119,7 @@ static void free_ldt_struct(struct ldt_s
    * we do not have to muck with descriptors here, that is
    * done in switch_mm() as needed.
    */
    -int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
    +int init_new_context_ldt(struct task_struct *tsk, struct mm_struct *mm)
    {
    struct ldt_struct *new_ldt;
    struct mm_struct *old_mm;
    @@ -160,7 +160,7 @@ out_unlock:
    *
    * 64bit: Don't touch the LDT register - we're already in the next thread.
    */
    -void destroy_context(struct mm_struct *mm)
    +void destroy_context_ldt(struct mm_struct *mm)
    {
    free_ldt_struct(mm->context.ldt);
    mm->context.ldt = NULL;

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