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Ryan Houdek
0f54369f9b
This is an interesting vdso implementation because it only exists in x86-64 with kernel v6.11. For Arm64 the implementation is likely to land in a couple kernel versions from now. Some differences with vdso_getrandom versus the regular getrandom syscall - Has two additional arguments, opaque_state and opaque_len - Expects the userspace to mmap/munmap this opaque state structure - Lets userspace query information about this structure upfront - If the opaque data structure isn't provided then it falls back to regular SYS_getrandom With the "glibc" implementation, we can tell the interface to allocate a single page that gets unused (otherwise glibc ends up not using the interface), and fallback to the regular SYS_getrandom. In the case of the vdso interface, currently the arguments just get passed through. Keeping this as a WIP until the ARM64 kernel patches land and I can actually test the things. Running the "glibc" path works today with the selftest, but the vdso path is currently completely untested.