[PATCH] Define vsyscall cache as blob to make clearer that user space shouldn't use it

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 7 insertions, 5 deletions

diff --git a/include/linux/getcpu.h b/include/linux/getcpu.h
index 031ed37..c7372d7 100644
--- a/include/linux/getcpu.h
+++ b/include/linux/getcpu.h
@@ -1,16 +1,18 @@
 #ifndef _LINUX_GETCPU_H
 #define _LINUX_GETCPU_H 1
 
-/* Cache for getcpu() to speed it up. Results might be upto a jiffie
+/* Cache for getcpu() to speed it up. Results might be a short time
    out of date, but will be faster.
+
    User programs should not refer to the contents of this structure.
-   It is only a cache for vgetcpu(). It might change in future kernels.
+   I repeat they should not refer to it. If they do they will break
+   in future kernels.
+
+   It is only a private cache for vgetcpu(). It will change in future kernels.
    The user program must store this information per thread (__thread)
    If you want 100% accurate information pass NULL instead. */
 struct getcpu_cache {
-	unsigned long t0;
-	unsigned long t1;
-	unsigned long res[4];
+	unsigned long blob[128 / sizeof(long)];
 };
 
 #endif