Re: [PATCH 3/6] i386 virtualization - Make ldt a desc struct

[Chuck Ebbert <76306.1226@compuserve.com>]

On Mon, 15 Aug 2005 at 15:59:39 -0700, zach@vmware.com wrote:

> --- linux-2.6.13.orig/include/asm-i386/mmu_context.h  2005-08-15 11:16:59.000000000 -0700
> +++ linux-2.6.13/include/asm-i386/mmu_context.h       2005-08-15 11:19:49.000000000 -0700
> @@ -19,7 +19,7 @@
>       memset(&mm->context, 0, sizeof(mm->context));
>       init_MUTEX(&mm->context.sem);
>       old_mm = current->mm;
> -     if (old_mm && unlikely(old_mm->context.size > 0)) {
> +     if (old_mm && unlikely(old_mm->context.ldt)) {  <==================
>               retval = copy_ldt(&mm->context, &old_mm->context);
>       }
>       if (retval == 0)
> @@ -32,7 +32,7 @@
>   */
>  static inline void destroy_context(struct mm_struct *mm)
>  {
> -     if (unlikely(mm->context.size))
> +     if (unlikely(mm->context.ldt))    <==================
>               destroy_ldt(mm);
>       del_lazy_mm(mm);
>  }

  Here you changed the code so it no longer tests the size field, however:

> --- linux-2.6.13.orig/arch/i386/kernel/ldt.c  2005-08-15 11:16:59.000000000 -0700
> +++ linux-2.6.13/arch/i386/kernel/ldt.c       2005-08-15 11:19:49.000000000 -0700
<--SNIP-->
> @@ -97,14 +96,16 @@
>  
>  void destroy_ldt(struct mm_struct *mm)
>  {
> +     int pages = mm->context.ldt_pages;
> +
>       if (mm == current->active_mm)
>               clear_LDT();
> -     ClearPagesLDT(mm->context.ldt, (mm->context.size * LDT_ENTRY_SIZE) / PAGE_SIZE);
> -     if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
> +     ClearPagesLDT(mm->context.ldt, pages);
> +     if (pages > 1)
>               vfree(mm->context.ldt);
>       else
>               kfree(mm->context.ldt);
> -     mm->context.size = 0;
> +     mm->context.ldt_pages = 0;   <====================
>  }
>  
>  static int read_ldt(void __user * ptr, unsigned long bytecount)

  destroy_ldt does not zero "ldt", just the size.  Potential bug?

  Also:

> --- linux-2.6.13.orig/arch/i386/kernel/ldt.c  2005-08-15 11:16:59.000000000 -0700
> +++ linux-2.6.13/arch/i386/kernel/ldt.c       2005-08-15 11:19:49.000000000 -0700
> @@ -28,28 +28,27 @@
>  }
>  #endif
>  
> -static inline int alloc_ldt(mm_context_t *pc, const int oldsize, int mincount, const int reload)
> +static inline int alloc_ldt(mm_context_t *pc, const int old_pages, int new_pages, const int reload)
>  {
> -     void *oldldt;
> -     void *newldt;
> +     struct desc_struct *oldldt;
> +     struct desc_struct *newldt;

  Can't this be declared on one line?


  ...and BTW could you add:

        QUILT_DIFF_OPTS=-p

to your shell env?  It makes the patches much easier to review.

__
Chuck
-
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