Prev: [net-next PATCH v6 0/3] net: reserve ports for applications using fixed port numbers
Next: [PATCH] dvb-core: Fix DoS bug in ULE decapsulation code that can be triggered by an invalid Payload Pointer
From: Alok Kataria on 26 Feb 2010 20:50

On Fri, 2010-02-26 at 09:16 -0800, Ian Campbell wrote:
> Preventing HIGHPTE allocations under VMI will allow us to remove the
> kmap_atomic_pte paravirt op.

Acked-by: Alok N Kataria <akataria(a)vmware.com>

Thanks,
Alok
>
> Signed-off-by: Ian Campbell <ian.campbell(a)citrix.com>
> Cc: Alok Kataria <akataria(a)vmware.com>
> Cc: H. Peter Anvin <hpa(a)zytor.com>
> Cc: Ingo Molnar <mingo(a)elte.hu>
> Cc: Jeremy Fitzhardinge <jeremy(a)goop.org>
> ---
> arch/x86/kernel/vmi_32.c | 23 +++++++++++------------
> 1 files changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
> index d430e4c..58aca86 100644
> --- a/arch/x86/kernel/vmi_32.c
> +++ b/arch/x86/kernel/vmi_32.c
> @@ -33,6 +33,7 @@
> #include <asm/fixmap.h>
> #include <asm/apicdef.h>
> #include <asm/apic.h>
> +#include <asm/pgalloc.h>
> #include <asm/processor.h>
> #include <asm/timer.h>
> #include <asm/vmi_time.h>
> @@ -272,19 +273,11 @@ static void *vmi_kmap_atomic_pte(struct page *page, enum km_type type)
> void *va = kmap_atomic(page, type);
>
> /*
> - * Internally, the VMI ROM must map virtual addresses to physical
> - * addresses for processing MMU updates. By the time MMU updates
> - * are issued, this information is typically already lost.
> - * Fortunately, the VMI provides a cache of mapping slots for active
> - * page tables.
> - *
> - * We use slot zero for the linear mapping of physical memory, and
> - * in HIGHPTE kernels, slot 1 and 2 for KM_PTE0 and KM_PTE1.
> - *
> - * args: SLOT VA COUNT PFN
> + * We disable highmem allocations for page tables so we should never
> + * see any calls to kmap_atomic_pte on a highmem page.
> */
> - BUG_ON(type != KM_PTE0 && type != KM_PTE1);
> - vmi_ops.set_linear_mapping((type - KM_PTE0)+1, va, 1, page_to_pfn(page));
> +
> + BUG_ON(PageHighmem(page));
>
> return va;
> }
> @@ -640,6 +633,12 @@ static inline int __init activate_vmi(void)
> u64 reloc;
> const struct vmi_relocation_info *rel = (struct vmi_relocation_info *)&reloc;
>
> + /*
> + * Prevent page tables from being allocated in highmem, even if
> + * CONFIG_HIGHPTE is enabled.
> + */
> + __userpte_alloc_gfp &= ~__GFP_HIGHMEM;
> +
> if (call_vrom_func(vmi_rom, vmi_init) != 0) {
> printk(KERN_ERR "VMI ROM failed to initialize!");
> return 0;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [net-next PATCH v6 0/3] net: reserve ports for applications using fixed port numbers
Next: [PATCH] dvb-core: Fix DoS bug in ULE decapsulation code that can be triggered by an invalid Payload Pointer