On 1/22/21 11:43 AM, Mark Brown wrote: > On Thu, Jan 21, 2021 at 12:54:52PM -0600, Josh Poimboeuf wrote: > >> 2) The shadow stack idea sounds promising -- how hard would it be to >> make a prototype reliable unwinder? > > In theory it doesn't look too hard and I can't see a particular reason > not to try doing this - there's going to be edge cases but hopefully for > reliable stack trace they're all in areas where we would be happy to > just decide the stack isn't reliable anyway, things like nesting which > allocates separate shadow stacks for each nested level for example. > I'll take a look. > I am a new comer to this discussion and I am learning. Just have some questions. Pardon me if they are obvious or if they have already been asked and answered. Doesn't Clang already have support for a shadow stack implementation for ARM64? We could take a look at how Clang does it. Will there not be a significant performance hit? May be, some of it can be mitigated by using a parallel shadow stack rather than a compact one. Are there any longjmp style situations in the kernel where the stack is unwound by several frames? In these cases, the shadow stack must be unwound accordingly. Madhavan > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
