tree 53b334864518dd27b243eafc9ab510ac56ee3b74
parent 8556e50994c8a8f5282fea008ae084d6d080648a
author Josef Bacik <jbacik@fb.com> 1513010208 -0500
committer Alexei Starovoitov <ast@kernel.org> 1513098154 -0800

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>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>