x86: add debug of invalid per_cpu map accesses

Provide a means to trap usages of per_cpu map variables before
they are setup.  Define CONFIG_DEBUG_PER_CPU_MAPS to activate.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 88420af9814..0a82b889d76 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -47,6 +47,18 @@ config DEBUG_PAGEALLOC
           This results in a large slowdown, but helps to find certain types
           of memory corruptions.
 
+config DEBUG_PER_CPU_MAPS
+        bool "Debug access to per_cpu maps"
+        depends on DEBUG_KERNEL
+        depends on X86_64_SMP
+        default n
+        help
+          Say Y to verify that the per_cpu map being accessed has
+          been setup.  Adds a fair amount of code to kernel memory
+          and decreases performance.
+
+          Say N if unsure.
+
 config DEBUG_RODATA
         bool "Write protect kernel read-only data structures"
         depends on DEBUG_KERNEL