From patchwork Wed Feb 8 09:50:52 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anju T Sudhakar X-Patchwork-Id: 725573 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vJGl32Nhnz9s7p for ; Wed, 8 Feb 2017 20:54:23 +1100 (AEDT) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3vJGl31bVvzDqSk for ; Wed, 8 Feb 2017 20:54:23 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vJGgL3bwqzDq5s for ; Wed, 8 Feb 2017 20:51:10 +1100 (AEDT) Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v189nHx3003257 for ; Wed, 8 Feb 2017 04:51:08 -0500 Received: from e28smtp01.in.ibm.com (e28smtp01.in.ibm.com [125.16.236.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 28g0fj1dn6-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 08 Feb 2017 04:51:07 -0500 Received: from localhost by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 8 Feb 2017 15:21:04 +0530 Received: from d28dlp02.in.ibm.com (9.184.220.127) by e28smtp01.in.ibm.com (192.168.1.131) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Wed, 8 Feb 2017 15:21:01 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 4FBB7394005C for ; Wed, 8 Feb 2017 15:21:01 +0530 (IST) Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay04.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v189p1q829753422 for ; Wed, 8 Feb 2017 15:21:01 +0530 Received: from d28av03.in.ibm.com (localhost [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v189ow26002221 for ; Wed, 8 Feb 2017 15:21:00 +0530 Received: from xenial-xerus.in.ibm.com (xenial-xerus.in.ibm.com [9.124.35.178]) by d28av03.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id v189ovpv002209; Wed, 8 Feb 2017 15:20:58 +0530 From: Anju T Sudhakar To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH v4 2/2] arch/powerpc: Optimize kprobe in kretprobe_trampoline Date: Wed, 8 Feb 2017 15:20:52 +0530 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1486547452-13510-1-git-send-email-anju@linux.vnet.ibm.com> References: <1486547452-13510-1-git-send-email-anju@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17020809-7323-0000-0000-000000BFBBC5 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17020809-7324-0000-0000-00000260D9C1 Message-Id: <1486547452-13510-3-git-send-email-anju@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-02-08_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702080098 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ananth@in.ibm.com, mahesh@linux.vnet.ibm.com, paulus@samba.org, mhiramat@kernel.org, naveen.n.rao@linux.vnet.ibm.com, hemant@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Kprobe placed on the kretprobe_trampoline during boot time can be optimized, since the instruction at probe point is a 'nop'. Signed-off-by: Anju T Sudhakar Acked-by: Masami Hiramatsu --- arch/powerpc/kernel/kprobes.c | 8 ++++++++ arch/powerpc/kernel/optprobes.c | 7 +++---- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index e785cc9..5b0fd07 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -282,6 +282,7 @@ asm(".global kretprobe_trampoline\n" ".type kretprobe_trampoline, @function\n" "kretprobe_trampoline:\n" "nop\n" + "blr\n" ".size kretprobe_trampoline, .-kretprobe_trampoline\n"); /* @@ -334,6 +335,13 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p, kretprobe_assert(ri, orig_ret_address, trampoline_address); regs->nip = orig_ret_address; + /* + * Make LR point to the orig_ret_address. + * When the 'nop' inside the kretprobe_trampoline + * is optimized, we can do a 'blr' after executing the + * detour buffer code. + */ + regs->link = orig_ret_address; reset_current_kprobe(); kretprobe_hash_unlock(current, &flags); diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index ecba221..5e4c254 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -72,12 +72,11 @@ static unsigned long can_optimize(struct kprobe *p) /* * kprobe placed for kretprobe during boot time - * is not optimizing now. - * - * TODO: Optimize kprobe in kretprobe_trampoline + * has a 'nop' instruction, which can be emulated. + * So further checks can be skipped. */ if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) - return 0; + return (unsigned long)p->addr + sizeof(kprobe_opcode_t); /* * We only support optimizing kernel addresses, but not