数据的一致性在不同 CPU 上访问得到了保证,为此必须要通过 TLB flush 操作的方式,invalid 其他几个 cpu 上 TLB entry 缓存,但是频繁执行 TLB flush 操作往往伴影响着业务的性能,导致部分核心业务出现性能抖动的情况,为此怎样减少 TLB flush 带来的影响,成为了很多开发者探索的方向。
There is no need to call this from tlb_flush_mmu_tlbonly, it logically belongs with tlb_flush_mmu_free. This makes future fixes simpler. [ This was originally done to allow code consolidation for the mmu_notifier fix, but it also ends up helping simplify the HAVE_RCU_TABLE_INVALIDATE fix...
并执行tlb flush操作,但是调用的是flush_tlb_page_nosync操作,既然DSB(ish)才能保证同步,那假如core1刚执行完__tlbi(vale1is异步操作,进程就被调度到core2上去了,由于只执行了异步操作,core2对应的极有可能保存着tlb entry,并且不知道发生了tlb flush操作,这样缓存一致性就无法保证了,并且由于进程被调度到core2,...
Flush-Cache/Page-Lock/Flush-TLB说明 查看原文 how TLB work 之前遇到了linux randomkernelpanic的问题,原因是TLB的entry对应的page其实已经释放。 VIP是独立的ko,create resource是通过VA接口走到我们ko... cahche不同的是,硬件不维护TLB的coherence,一旦软件修改了pagetable,软件也要进程TLBinvalidate操作,以维护...
TLB之flush操作[一] 【相关指令】 在ARMv8-A中,TLB flush/invalidate(通常ARM/x86处理器手册中称为invalidate,linux系统中称为flush,以下的讨论统称为flush)的指令为: TLBI <type><level>{IS} {, <Xt>} 其中,"level"为1到3,对应ARMv8的三个exception level,即EL1,EL2,EL3,通常EL1运行linux等操作系统...
Linux3.10内核代码中对于TLB刷新,定义了如下接口: 点击(此处)折叠或打开/*flush mm相关的TLB项,即flush指定进程相关的TLB项*/staticinlinevoidflush_tlb_mm(structmm_struct *mm) {/*要求被flush的mm必须是当前的active mm,因为只有active mm对应的映射才存在于硬件TLB中*/if(mm == current->active_mm) ...
Linux: mremap() TLB flush too late with concurrent ftruncate() CVE-2018-18281 Tested on the master branch (4.19.0-rc7+). sys_mremap() takes current->mm->mmap_sem for writing, then calls mremap_to()->move_vma()->move_page_tables(). move_page_tables() first ...
+#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL void kvm_flush_remote_tlbs(struct kvm *kvm) { long dirty_count = kvm->tlbs_dirty; @@ -195,6 +196,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm) cmpxchg(&kvm->tlbs_dirty, dirty_count, 0); ...
(u64, tlbstate_untag_mask); void __flush_tlb_all(void); #define TLB_FLUSH_ALL -1UL #define TLB_GENERATION_INVALID 0 void cr4_update_irqsoff(unsigned long set, unsigned long clear); unsigned long cr4_read_shadow(void); /* Set in this cpu's CR4. */ static inline void cr4_set...
for a quadcore it maybe was ok, but if i have in the future 64 cores running and everys time i change a page the cores have to invaldiate that page by hand in 64 CPUs or - even worse - flush the whole TLB then i expect a better solution. best regards Dennis0...