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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 31 Mar 2020 07:13:15 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 02V6DKsC46727438 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 31 Mar 2020 06:13:20 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 737C4A404D; Tue, 31 Mar 2020 06:13:20 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 13958A4040; Tue, 31 Mar 2020 06:13:20 +0000 (GMT) Received: from localhost (unknown [9.85.74.140]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 31 Mar 2020 06:13:19 +0000 (GMT) Date: Tue, 31 Mar 2020 11:43:18 +0530 From: "Naveen N. Rao" Subject: Re: [PATCH 10/12] powerpc/entry32: Blacklist exception entry points for kprobe. To: Benjamin Herrenschmidt , Christophe Leroy , Michael Ellerman , Paul Mackerras References: <1585588031.jvow7mwq4x.naveen@linux.ibm.com> <7f367f35-1bb8-bbb6-f399-8e911f76e043@c-s.fr> In-Reply-To: <7f367f35-1bb8-bbb6-f399-8e911f76e043@c-s.fr> MIME-Version: 1.0 User-Agent: astroid/v0.15-13-gb675b421 (https://github.com/astroidmail/astroid) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 x-cbid: 20033106-0012-0000-0000-0000039B6993 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20033106-0013-0000-0000-000021D8745C Message-Id: <1585634956.dtpgv9vena.naveen@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-03-31_02:2020-03-30, 2020-03-31 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 bulkscore=0 phishscore=0 malwarescore=0 priorityscore=1501 suspectscore=0 clxscore=1015 mlxlogscore=999 impostorscore=0 lowpriorityscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003310048 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy wrote: >=20 >=20 > Le 30/03/2020 =C3=A0 19:08, Naveen N. Rao a =C3=A9crit=C2=A0: >> Christophe Leroy wrote: >>> kprobe does not handle events happening in real mode. >>> >>> As exception entry points are running with MMU disabled, >>> blacklist them. >>> >>> Signed-off-by: Christophe Leroy >>> --- >>> =C2=A0arch/powerpc/kernel/entry_32.S | 7 +++++++ >>> =C2=A01 file changed, 7 insertions(+) >>> >>> diff --git a/arch/powerpc/kernel/entry_32.S=20 >>> b/arch/powerpc/kernel/entry_32.S >>> index 94f78c03cb79..9a1a45d6038a 100644 >>> --- a/arch/powerpc/kernel/entry_32.S >>> +++ b/arch/powerpc/kernel/entry_32.S >>> @@ -51,6 +51,7 @@ mcheck_transfer_to_handler: >>> =C2=A0=C2=A0=C2=A0=C2=A0 mfspr=C2=A0=C2=A0=C2=A0 r0,SPRN_DSRR1 >>> =C2=A0=C2=A0=C2=A0=C2=A0 stw=C2=A0=C2=A0=C2=A0 r0,_DSRR1(r11) >>> =C2=A0=C2=A0=C2=A0=C2=A0 /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler) >>> >>> =C2=A0=C2=A0=C2=A0=C2=A0 .globl=C2=A0=C2=A0=C2=A0 debug_transfer_to_han= dler >>> =C2=A0debug_transfer_to_handler: >>> @@ -59,6 +60,7 @@ debug_transfer_to_handler: >>> =C2=A0=C2=A0=C2=A0=C2=A0 mfspr=C2=A0=C2=A0=C2=A0 r0,SPRN_CSRR1 >>> =C2=A0=C2=A0=C2=A0=C2=A0 stw=C2=A0=C2=A0=C2=A0 r0,_CSRR1(r11) >>> =C2=A0=C2=A0=C2=A0=C2=A0 /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler) >>> >>> =C2=A0=C2=A0=C2=A0=C2=A0 .globl=C2=A0=C2=A0=C2=A0 crit_transfer_to_hand= ler >>> =C2=A0crit_transfer_to_handler: >>> @@ -94,6 +96,7 @@ crit_transfer_to_handler: >>> =C2=A0=C2=A0=C2=A0=C2=A0 rlwinm=C2=A0=C2=A0=C2=A0 r0,r1,0,0,(31 - THREA= D_SHIFT) >>> =C2=A0=C2=A0=C2=A0=C2=A0 stw=C2=A0=C2=A0=C2=A0 r0,KSP_LIMIT(r8) >>> =C2=A0=C2=A0=C2=A0=C2=A0 /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler) >>> =C2=A0#endif >>> >>> =C2=A0#ifdef CONFIG_40x >>> @@ -115,6 +118,7 @@ crit_transfer_to_handler: >>> =C2=A0=C2=A0=C2=A0=C2=A0 rlwinm=C2=A0=C2=A0=C2=A0 r0,r1,0,0,(31 - THREA= D_SHIFT) >>> =C2=A0=C2=A0=C2=A0=C2=A0 stw=C2=A0=C2=A0=C2=A0 r0,KSP_LIMIT(r8) >>> =C2=A0=C2=A0=C2=A0=C2=A0 /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler) >>> =C2=A0#endif >>> >>> =C2=A0/* >>> @@ -127,6 +131,7 @@ crit_transfer_to_handler: >>> =C2=A0=C2=A0=C2=A0=C2=A0 .globl=C2=A0=C2=A0=C2=A0 transfer_to_handler_f= ull >>> =C2=A0transfer_to_handler_full: >>> =C2=A0=C2=A0=C2=A0=C2=A0 SAVE_NVGPRS(r11) >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_full) >>> =C2=A0=C2=A0=C2=A0=C2=A0 /* fall through */ >>> >>> =C2=A0=C2=A0=C2=A0=C2=A0 .globl=C2=A0=C2=A0=C2=A0 transfer_to_handler >>> @@ -286,6 +291,8 @@ reenable_mmu: >>> =C2=A0=C2=A0=C2=A0=C2=A0 lwz=C2=A0=C2=A0=C2=A0 r2, GPR2(r11) >>> =C2=A0=C2=A0=C2=A0=C2=A0 b=C2=A0=C2=A0=C2=A0 fast_exception_return >>> =C2=A0#endif >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler) >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont) >>=20 >> These are added after 'reenable_mmu', which is itself not blacklisted.=20 >> Is that intentional? >=20 > Yes I put it as the complete end of the entry part, ie just before=20 > stack_ovf which is a function by itself. >=20 > Note that reenable_mmu is inside an #ifdef CONFIG_TRACE_IRQFLAGS. >=20 > I'm not completely sure where to put the _ASM_NOKPROBE_SYMBOL()s, that's=20 > the reason why I put it close to the symbol itself in my first series. Ok, I see what you mean. 'reenable_mmu' can probably be moved after the=20 end of 'transfer_to_handler_cont' (as also removing what looks to be an=20 unused label '1' for the branch to trace_hardirqs_off), but that's a=20 minor thing. From the blacklisting point, this is not an issue. - Naveen