How to take advantage of the VDSO object with your own programming language?

Question

Recent Linux kernels (at least on amd64) provide a magic object file called linux-vdso.so.1 that abstracts away the syscall interface to the kernel, allowing the ke

Answer 1

I found these files in the Linux kernel tree helpful:

• Documentation/ABI/stable/vdso (what is the vDSO object?)
• Documentation/vDSO/parse_vdso.c (Reference parser for the vDSO object)

The vDSO object is a virtual dynamic shared object that is always mapped into the address space of an amd64 process under linux. It can be used to implement quick system calls. To access the functions inside the vDSO object, you need to

• locate the object
• extract an address from the symbol table

Both things can be done with the CC0 licensed reference implementation parse_vdso.c.