tree 80e320112959e90d474fd20e644b8377217dad0b
parent 54985120a1c461b74f9510e5d730971f2a2383b1
author Josef Bacik <jbacik@fb.com> 1510086522 -0500
committer David S. Miller <davem@davemloft.net> 1510370285 +0900

bpf: add a bpf_override_function helper

Error injection is sloppy and very ad-hoc.  BPF could fill this niche
perfectly with it's kprobe functionality.  We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations.  Accomplish this with the bpf_override_funciton
helper.  This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function.  This gives us a nice
clean way to implement systematic error injection for all of our code
paths.

Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>