On Tue, Jun 15, 2021 at 08:21:12PM -0700, Andy Lutomirski wrote: > On arm32, the only way to safely flush icache from usermode is to call > cacheflush(2). This also handles any required pipeline flushes, so > membarrier's SYNC_CORE feature is useless on arm. Remove it. So SYNC_CORE is there to help an architecture that needs to do something per CPU. If I$ invalidation is broadcast and I$ invalidation also triggers the flush of any uarch caches derived from it (if there are any). Now arm_syscall() NR(cacheflush) seems to do flush_icache_user_range(), which, if I read things right, end up in arch/arm/mm/*.S, but that doesn't consider cache_ops_need_broadcast(). Will suggests that perhaps ARM 11MPCore might need this due to their I$ flush maybe not being broadcast
