The Linux kernel OpenRISC implementation had a flaw in the jump label SMP syncing code introduced by commit 8c30b0018f9d. It incorrectly reused ARM64 cache invalidation logic that does not properly invalidate instruction caches on remote OpenRISC cores. This caused stale static key code sequences to remain after static_branch_enable() calls, leading to potential inconsistencies in static key state. The patch fixes this by using icache_all_inv to properly invalidate remote instruction caches and flushing the data cache on architectures without writethrough caches. Testing confirmed the fix resolves the jump label coherency issue.

The vulnerability could cause stale instruction cache lines to persist on remote cores in SMP systems, potentially leading to incorrect static key state after updates. This may affect kernel behavior relying on static keys for conditional code paths, possibly causing inconsistent or unexpected execution flows. No known exploits in the wild have been reported.

This vulnerability has been resolved by an official fix in the Linux kernel. Users should update to the fixed kernel version containing the patch that properly invalidates remote instruction caches on OpenRISC SMP systems. No additional mitigation actions are required beyond applying the official patch.