tree 962f0b570a299c36ea29f9dd2cb14943b488ca68
parent a2308c11ecbc3471ebb7435ee8075815b1502ef0
author Heiko Carstens <heiko.carstens@de.ibm.com> 1574066317 +0100
committer Vasily Gorbik <gor@linux.ibm.com> 1575107564 +0100

s390/vdso: fix getcpu

getcpu reads the required values for cpu and node with two
instructions. This might lead to an inconsistent result if user space
gets preempted and migrated to a different CPU between the two
instructions.

Fix this by using just a single instruction to read both values at
once.

This is currently rather a theoretical bug, since there is no real
NUMA support available (except for NUMA emulation).

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>