lockdep: ipipe: make the logic aware of interrupt pipelining
The lockdep engine will check for the current interrupt state as part of the locking validation process, which must encompass: - the CPU interrupt state - the current pipeline domain - the virtual interrupt disable flag so that we can traverse the tracepoints from any context sanely and safely. In addition trace_hardirqs_on_virt_caller() should be called by the arch-dependent code when tracking the interrupt state before returning to user-space after a kernel entry (exceptions, IRQ). This makes sure that the tracking logic only applies to the root domain, and considers the virtual disable flag exclusively. For instance, the kernel may be entered when interrupts are (only) virtually disabled for the root domain (i.e. stalled), and we should tell the IRQ tracing logic that IRQs are about to be enabled back only if the root domain is unstalled before leaving to user-space. In such a context, the state of the interrupt bit in the CPU would be irrelevant.