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[PATCH 3/3] powerpc: kprobes: emulate instructions on kprobe handler re-entry

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  [PATCH 3/3] powerpc: kprobes: emulate instructions on kprobe handler re-entry "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-02-14 09:40 +0100
    Re: [PATCH 3/3] powerpc: kprobes: emulate instructions on kprobe  handler re-entry Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> - 2017-02-14 09:50 +0100

#1580392 — [PATCH 3/3] powerpc: kprobes: emulate instructions on kprobe handler re-entry

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

As a related change, remove the duplicate saving of msr as that is
already done in set_current_kprobe()

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/kprobes.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 9cdf2de31e9e..c213637b9d25 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -206,10 +206,17 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 			 */
 			save_previous_kprobe(kcb);
 			set_current_kprobe(p, regs, kcb);
-			kcb->kprobe_saved_msr = regs->msr;
 			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) {
-- 
2.11.0

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#1580398 — Re: [PATCH 3/3] powerpc: kprobes: emulate instructions on kprobe handler re-entry

On Tue, Feb 14, 2017 at 02:08:03PM +0530, Naveen N. Rao wrote:
> On kprobe handler re-entry, try to emulate the instruction rather than
> single stepping always.
> 
> As a related change, remove the duplicate saving of msr as that is
> already done in set_current_kprobe()
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Acked-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>

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