powerpc/kprobes: Clean up jprobe detection in livepatch handler

In commit c05b8c4474c03 ("powerpc/kprobes: Skip livepatch_handler() for
jprobes"), we added a helper is_current_kprobe_addr() to help detect if
the modified regs->nip was due to a jprobe or livepatch. Masami felt
that the function name was not quite clear. To that end, this patch
renames is_current_kprobe_addr() to __is_active_jprobe() and adds a
comment to (hopefully) better clarify the purpose of this helper. The
helper has also now been moved to kprobes-ftrace.c so that it is only
available for KPROBES_ON_FTRACE.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c
index 6c089d9757c9..48f675a73cff 100644
--- a/arch/powerpc/kernel/kprobes-ftrace.c
+++ b/arch/powerpc/kernel/kprobes-ftrace.c
@@ -25,6 +25,17 @@
 #include <linux/preempt.h>
 #include <linux/ftrace.h>
 
+/*
+ * This is called from ftrace code after invoking registered handlers to
+ * disambiguate regs->nip changes done by jprobes and livepatch. We check if
+ * there is an active jprobe at the provided address (mcount location).
+ */
+int __is_active_jprobe(unsigned long addr)
+{
+	struct kprobe *p = kprobe_running();
+	return (p && (unsigned long)p->addr == addr) ? 1 : 0;
+}
+
 static nokprobe_inline
 int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
 		      struct kprobe_ctlblk *kcb, unsigned long orig_nip)