From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 3zxKL13WX6zF1nt for ; Thu, 8 Mar 2018 03:46:49 +1100 (AEDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w27GjBj9147155 for ; Wed, 7 Mar 2018 11:46:46 -0500 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0b-001b2d01.pphosted.com with ESMTP id 2gjjmrkph4-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Wed, 07 Mar 2018 11:46:46 -0500 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 7 Mar 2018 16:46:42 -0000 From: "Naveen N. Rao" To: Benjamin Herrenschmidt , Michael Ellerman , Paul Mackerras , Steven Rostedt Cc: Anton Blanchard , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Subject: [RFC PATCH 1/1] powerpc/ftrace: Exclude real mode code from Date: Wed, 7 Mar 2018 22:16:19 +0530 In-Reply-To: References: In-Reply-To: References: Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , We can't take a trap in most parts of real mode code. Instead of adding the 'notrace' annotation to all C functions that can be invoked from real mode, detect that we are in real mode on ftrace entry and return back. Signed-off-by: Naveen N. Rao --- This RFC only handles -mprofile-kernel to demonstrate the approach being considered. We will need to handle other ftrace entry if we decide to continue down this path. - Naveen arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S index 3f3e81852422..ecc0e8e38ead 100644 --- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S @@ -56,6 +56,21 @@ _GLOBAL(ftrace_caller) /* Load special regs for save below */ mfmsr r8 + + /* Only proceed if we are not in real mode and can take interrupts */ + andi. r9, r8, MSR_IR|MSR_DR|MSR_RI + cmpdi r9, MSR_IR|MSR_DR|MSR_RI + beq 1f + mflr r8 + mtctr r8 + REST_GPR(9, r1) + REST_GPR(8, r1) + addi r1, r1, SWITCH_FRAME_SIZE + ld r0, LRSAVE(r1) + mtlr r0 + bctr + +1: mfctr r9 mfxer r10 mfcr r11 -- 2.16.1