[v2, 3/4] powerpc/kprobes_on_ftrace: Skip livepatch_handler() for jprobes

[Michael Ellerman]

On Thu, 2017-06-01 at 10:48:17 UTC, "Naveen N. Rao" wrote:
> ftrace_caller() depends on a modified regs->nip to detect if a certain
> function has been livepatched. However, with KPROBES_ON_FTRACE, it is
> possible for regs->nip to have been modified by the kprobes pre_handler
> (jprobes, for instance). In this case, we do not want to invoke the
> livepatch_handler so as not to consume the livepatch stack.
> 
> To distinguish between the two (kprobes and livepatch), we check if
> there is an active kprobe on the current function. If there is, then we
> know for sure that it must have modified the NIP as we don't support
> livepatching a kprobe'd function. In this case, we simply skip the
> livepatch_handler and branch to the new NIP. Otherwise, the
> livepatch_handler is invoked.
> 
> Fixes: ead514d5fb30a ("powerpc/kprobes: Add support for
> KPROBES_ON_FTRACE")
> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> Reviewed-by: Masami Hiramatsu <mhiramat at kernel.org>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/c05b8c4474c03026aaa7f8872e7836

cheers