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SubjectRe: [PATCH] adjust/fix LDT handling for Xen
On 01/11/2008 10:22 AM, Jan Beulich wrote:
> Don't rely on kmalloc(PAGE_SIZE) returning PAGE_SIZE aligned memory
> (Xen requires GDT *and* LDT to be page-aligned). Using the page
> allocator interface also removes the (albeit small) slab allocator
> overhead. The same change being done for 64-bits for consistency.
>
> Further, the Xen hypercall interface expects the LDT address to be
> virtual, not machine.
>
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
> Cc: Ingo Molnar <mingo@elte.hu>
>
> ---
> arch/x86/kernel/ldt_32.c | 7 +++----
> arch/x86/kernel/ldt_64.c | 7 +++----
> arch/x86/xen/enlighten.c | 9 +--------
> 3 files changed, 7 insertions(+), 16 deletions(-)
>
> --- linux-2.6.24-rc7/arch/x86/kernel/ldt_32.c 2008-01-10 16:53:54.000000000 +0100
> +++ 2.6.24-rc7-x86-xen-ldt/arch/x86/kernel/ldt_32.c 2008-01-09 13:59:50.000000000 +0100
[...]
> @@ -73,7 +72,7 @@ static int alloc_ldt(mm_context_t *pc, u
> if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE)
> vfree(oldldt);
> else
> - kfree(oldldt);
> + put_page(virt_to_page(oldldt));
> }
> return 0;
> }
> @@ -117,7 +116,7 @@ void destroy_context(struct mm_struct *m
> if ((unsigned)mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
> vfree(mm->context.ldt);
> else
> - kfree(mm->context.ldt);
> + put_page(virt_to_page(mm->context.ldt));

why not free_page() with all those checks if it is correct virt address which it
brings?

regards,
--
Jiri Slaby
Faculty of Informatics, Masaryk University
Suse Labs


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