[Xen-changelog] [linux-2.6.18-xen] xen/x86-64: kern_addr_valid() must not walk page tables mapping hypervisor space

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1271090074 -3600
# Node ID fbe371367af64674d8eefa59924890a7b783f769
# Parent  11175e60d39349f7daf5672481f25b9546f0918e
xen/x86-64: kern_addr_valid() must not walk page tables mapping hypervisor space

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 arch/x86_64/mm/init-xen.c |   13 +++++++++++++
 1 files changed, 13 insertions(+)

diff -r 11175e60d393 -r fbe371367af6 arch/x86_64/mm/init-xen.c
--- a/arch/x86_64/mm/init-xen.c Tue Mar 30 18:28:34 2010 +0100
+++ b/arch/x86_64/mm/init-xen.c Mon Apr 12 17:34:34 2010 +0100
@@ -1149,6 +1149,19 @@ int kern_addr_valid(unsigned long addr)
        if (above != 0 && above != -1UL)
                return 0; 
        
+#ifdef CONFIG_XEN
+       /*
+        * Don't walk page tables for hypervisor addresses, but allow
+        * the M2P table to be accessed through e.g. /proc/kcore.
+        */
+       if (addr >= (unsigned long)machine_to_phys_mapping &&
+           addr < (unsigned long)(machine_to_phys_mapping +
+                                  (1UL << machine_to_phys_order)))
+               return 1;
+       if (addr >= HYPERVISOR_VIRT_START && addr < HYPERVISOR_VIRT_END)
+               return 0;
+#endif
+
        pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd))
                return 0;

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