elf bpf_probe_read to bpf_probe_read_kernel rewrite port from libbpf

[jasonk000]

Kernel has changed to use bpf_probe_read_kernel instead of bpf_probe_read which is resulting in some issues with an ELF binary and attached kprobe. Compiling the ELF file to use bpf_probe_read_kernel resolves it; however that makes the ELF file not backwards compatible.

Libbpf handles this by detecting the available feature and performing a rewrite of the instructions as shown here.

There is no currently no sanitization step, in gobpf, so it would need to be built.

If there is interest I'd be happy to draft a patch. I expect a new function called by elf.go:Load around line 537 or line 833 to rewrite the insns at that point would resolve it. Some integration to detect kernel features would also be needed.