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    Subject[PATCH 32/37] x86: separate out LDT init from context init
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    From: Dave Hansen <dave.hansen@linux.intel.com>

    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>
    ---

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

    diff -puN arch/x86/include/asm/mmu_context.h~init-ldt-extricate arch/x86/include/asm/mmu_context.h
    --- a/arch/x86/include/asm/mmu_context.h~init-ldt-extricate 2015-11-16 12:35:50.266849426 -0800
    +++ b/arch/x86/include/asm/mmu_context.h 2015-11-16 12:35:50.271849653 -0800
    @@ -53,15 +53,15 @@ 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)
    @@ -105,6 +105,17 @@ static inline void enter_lazy_tlb(struct
    #endif
    }

    +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);
    +}
    +
    static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
    struct task_struct *tsk)
    {
    diff -puN arch/x86/kernel/ldt.c~init-ldt-extricate arch/x86/kernel/ldt.c
    --- a/arch/x86/kernel/ldt.c~init-ldt-extricate 2015-11-16 12:35:50.268849517 -0800
    +++ b/arch/x86/kernel/ldt.c 2015-11-16 12:35:50.272849698 -0800
    @@ -103,7 +103,7 @@ 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;
    @@ -144,7 +144,7 @@ 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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