On Tue 2023-01-24 19:38:05, Josh Poimboeuf wrote: > When a module with a livepatched function is unloaded and then reloaded, > klp attempts to dynamically re-patch it. On ppc64, that fails with the > following error: > > module_64: livepatch_nfsd: Expected nop after call, got e8410018 at e_show+0x60/0x548 [livepatch_nfsd] > livepatch: failed to initialize patch 'livepatch_nfsd' for module 'nfsd' (-8) > livepatch: patch 'livepatch_nfsd' failed for module 'nfsd', refusing to load module 'nfsd' > > The error happens because the restore r2 instruction had already > previously been written into the klp module's replacement function when > the original function was patched the first time. So the instruction > wasn't a nop as expected. > > When the restore r2 instruction has already been patched in, detect that > and skip the warning and the instruction write. > > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> It seems that the function does what it says. And it seems to be the only location where an instruction is checked before it is modified. I am fine with this approach. Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> Best Regards, Petr
