[git pull] core, x86: make LIST_POISON less deadly

[Ingo Molnar]

Linus,

Please pull the safe-poison-pointers commit from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git safe-poison-pointers

this didnt fit into any of the other categories and affects all 
architectures (via the opt-in CONFIG_ILLEGAL_POINTER_VALUE).

Thanks,

	Ingo

------------------>
Avi Kivity (1):
      core, x86: make LIST_POISON less deadly


 arch/x86/Kconfig       |    5 +++++
 include/linux/poison.h |   10 ++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e0edaaa..f09b3e5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1019,6 +1019,11 @@ config ARCH_MEMORY_PROBE
 	def_bool X86_64
 	depends on MEMORY_HOTPLUG
 
+config ILLEGAL_POINTER_VALUE
+       hex
+       default 0 if X86_32
+       default 0xffffc10000000000 if X86_64
+
 source "mm/Kconfig"
 
 config HIGHPTE
diff --git a/include/linux/poison.h b/include/linux/poison.h
index 9f31683..0d105a5 100644
--- a/include/linux/poison.h
+++ b/include/linux/poison.h
@@ -1,14 +1,20 @@
 #ifndef _LINUX_POISON_H
 #define _LINUX_POISON_H
 
+#ifdef CONFIG_ILLEGAL_POINTER_VALUE
+#define POISON_POINTER_DELTA CONFIG_ILLEGAL_POINTER_VALUE
+#else
+#define POISON_POINTER_DELTA 0L
+#endif
+
 /********** include/linux/list.h **********/
 /*
  * These are non-NULL pointers that will result in page faults
  * under normal circumstances, used to verify that nobody uses
  * non-initialized list entries.
  */
-#define LIST_POISON1  ((void *) 0x00100100)
-#define LIST_POISON2  ((void *) 0x00200200)
+#define LIST_POISON1  ((void *) 0x00100100 + POISON_POINTER_DELTA)
+#define LIST_POISON2  ((void *) 0x00200200 + POISON_POINTER_DELTA)
 
 /********** include/linux/timer.h **********/
 /*
--
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