On Thu, 15 Sept 2022 at 10:47, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Thu, Sep 15, 2022 at 10:56:58AM +0800, Chen Zhongjin wrote: > > > We have found some anonymous information on x86 in .rodata. > > Well yes, but that's still a bunch of heuristics on our side. > > > I'm not sure if those are *all* of Josh wanted on x86, however for arm64 we > > did not found that in the same section so it is a problem on arm64 now. > > Nick found Bolt managed the ARM64 jumptables: > > https://github.com/llvm/llvm-project/blob/main/bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp#L484 > > But that does look like a less than ideal solution too. > > > Does the compiler will emit these for all arches? At lease I tried and > > didn't find anything meaningful (maybe I omitted it). > > That's the question; can we get the compiler to help us here in a well > defined manner. Do BTI landing pads help at all here? I.e., I assume that objtool just treats any indirect call as a dangling edge in the control flow graph, and the problem is identifying the valid targets. In the BTI case, those will all start with a 'BTI J' instruction.