Hi Ryan, Thanks for the patch. Ryan Sullivan <rysulliv@xxxxxxxxxx> writes: > Currently, on PowerPC machines, sibling calls in livepatched functions > cause the stack to be corrupted and are thus not supported by tools > such as kpatch. Below is an example stack frame showing one such > currupted stacks: ... > diff --git a/arch/powerpc/kernel/trace/ftrace_entry.S b/arch/powerpc/kernel/trace/ftrace_entry.S > index 76dbe9fd2c0f..4dfbe6076ad1 100644 > --- a/arch/powerpc/kernel/trace/ftrace_entry.S > +++ b/arch/powerpc/kernel/trace/ftrace_entry.S > @@ -244,6 +244,9 @@ livepatch_handler: > mtlr r12 > ld r2, -24(r11) > > + /* Restore toc to caller's stack in case of sibling call */ > + std r2, 24(r1) > + It would be good to have a comment here explaining why it's safe in all cases to store the current r2 value back to the caller's save slot. I haven't convinced myself that it is always safe, but I need to think about it a bit harder O_o cheers
