From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Date: Wed, 19 Apr 2017 12:51:05 +0000 (+0530)
Subject: powerpc/kprobes: Emulate instructions on kprobe handler re-entry
X-Git-Tag: v4.12-rc1~93^2~49^2~4
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=22d8b3dec214c;p=karo-tx-linux.git

powerpc/kprobes: Emulate instructions on kprobe handler re-entry

On kprobe handler re-entry, try to emulate the instruction rather than single
stepping always.

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

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index ed5a917c2edd..b71922618ed2 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -277,6 +277,14 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 			kprobes_inc_nmissed_count(p);
 			prepare_singlestep(p, regs);
 			kcb->kprobe_status = KPROBE_REENTER;
+			if (p->ainsn.boostable >= 0) {
+				ret = try_to_emulate(p, regs);
+
+				if (ret > 0) {
+					restore_previous_kprobe(kcb);
+					return 1;
+				}
+			}
 			return 1;
 		} else {
 			if (*addr != BREAKPOINT_INSTRUCTION) {