From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 3w7MNv5d7YzDq9m for ; Wed, 19 Apr 2017 22:53:03 +1000 (AEST) 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 v3JCniYS068619 for ; Wed, 19 Apr 2017 08:52:52 -0400 Received: from e28smtp06.in.ibm.com (e28smtp06.in.ibm.com [125.16.236.6]) by mx0a-001b2d01.pphosted.com with ESMTP id 29x752upab-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 19 Apr 2017 08:52:50 -0400 Received: from localhost by e28smtp06.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 19 Apr 2017 18:22:46 +0530 Received: from d28av08.in.ibm.com (d28av08.in.ibm.com [9.184.220.148]) by d28relay07.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v3JCpJpJ14876698 for ; Wed, 19 Apr 2017 18:21:19 +0530 Received: from d28av08.in.ibm.com (localhost [127.0.0.1]) by d28av08.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v3JCqgNZ020239 for ; Wed, 19 Apr 2017 18:22:43 +0530 From: "Naveen N. Rao" To: Michael Ellerman Cc: Ananth N Mavinakayanahalli , Masami Hiramatsu , Ingo Molnar , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/6] powerpc: ftrace: restore LR from pt_regs Date: Wed, 19 Apr 2017 18:22:24 +0530 In-Reply-To: References: In-Reply-To: References: Message-Id: <5aa5ca47d531a530285fe5b453f6921d0960bde3.1492606062.git.naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Pass the real LR to the ftrace handler. This is needed for KPROBES_ON_FTRACE for the pre handlers. Also, with KPROBES_ON_FTRACE, the link register may be updated by the pre handlers or by a registed kretprobe. Honor updated LR by restoring it from pt_regs, rather than from the stack save area. Live patch and function graph continue to work fine with this change. Signed-off-by: Naveen N. Rao --- arch/powerpc/kernel/entry_64.S | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 8fd8718722a1..744b2f91444a 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1248,9 +1248,10 @@ _GLOBAL(ftrace_caller) /* Get the _mcount() call site out of LR */ mflr r7 - /* Save it as pt_regs->nip & pt_regs->link */ + /* Save it as pt_regs->nip */ std r7, _NIP(r1) - std r7, _LINK(r1) + /* Save the read LR in pt_regs->link */ + std r0, _LINK(r1) /* Save callee's TOC in the ABI compliant location */ std r2, 24(r1) @@ -1297,16 +1298,16 @@ ftrace_call: REST_8GPRS(16,r1) REST_8GPRS(24,r1) + /* Restore possibly modified LR */ + ld r0, _LINK(r1) + mtlr r0 + /* Restore callee's TOC */ ld r2, 24(r1) /* Pop our stack frame */ addi r1, r1, SWITCH_FRAME_SIZE - /* Restore original LR for return to B */ - ld r0, LRSAVE(r1) - mtlr r0 - #ifdef CONFIG_LIVEPATCH /* Based on the cmpd above, if the NIP was altered handle livepatch */ bne- livepatch_handler -- 2.12.1