On Sat, Nov 7, 2020 at 9:18 PM Dmitry Safonov <dima@xxxxxxxxxx> wrote: > > Instead of having every architecture to define vdso_base/vdso_addr etc, > provide a generic mechanism to track landing in userspace. > It'll minimize per-architecture difference, the number of callbacks to > provide. > > Originally, it started from thread [1] where the need for .close() > callback on vm_special_mapping was pointed, this generic code besides > removing duplicated .mremap() callbacks provides a cheaper way to > support munmap() on vdso mappings without introducing .close() callbacks > for every architecture (with would bring even more code duplication). I find the naming odd. It's called "user_landing", which is presumably a hard-to-understand shorthand for "user mode landing pad for return from a signal handler if SA_RESTORER is not set". But, looking at the actual code, it's not this at all -- it's just the vDSO base address. So how about just calling it vdso_base? I'm very much in favor of consolidating and cleaning up, and improving the vdso remap/unmap code, but I'm not convinced that we should call it anything other than the vdso base. --Andy
