On Tue, Jan 09, 2018 at 02:43:08PM +0000, David Woodhouse wrote: > From: Andi Kleen <[email protected]> > > objtool's assembler currently cannot deal with the code generated by the > retpoline compiler and throws hundreds of warnings, mostly because it sees > calls that don't have a symbolic target. > > Exclude all the options that rely on objtool when RETPOLINE is active. > > This mainly means that the kernel has to fallback to use the frame pointer > unwinder and livepatch is not supported. > > Josh is looking into resolving the issue.
I have a fix brewing for this, in two parts: - Part 1 will allow objtool to understand the flow *around* the retpolines (but not *inside* them). Which basically means that ORC will still get confused if it tries to unwind from inside a retpoline, but otherwise it should work fine. This code is pretty much done, just need to do some testing with it first. This should allow us to re-enable objtool and friends: ORC, reliable stacks, livepatch consistency model. - Part 2 will add ORC annotations for inside the retpolines. This will be a little harder, but I have my fingers crossed that it's do-able within a week or so. -- Josh
