On Mon, Apr 18, 2022 at 08:28:33PM +0800, Chen Zhongjin wrote: > Hi Josh, > > IIUC, ORC on x86 can make reliable stack unwind for this scenario > because objtool validates BP state. > > I'm thinking that on arm64 there's no guarantee that LR will be pushed > onto stack. When we meet similar scenario on arm64, we should recover > (LR, FP) on pt_regs and continue to unwind the stack. And this is > reliable only after we validate (LR, FP). > > So should we track LR on arm64 additionally as track BP on x86? Or can > we just treat (LR, FP) as a pair? because as I know they are always set > up together. Does the arm64 unwinder have a way to detect kernel pt_regs on the stack? If so, the simplest solution is to mark all stacks with kernel regs as unreliable. That's what the x86 FP unwinder does. -- Josh
