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Wed, 22 Apr 2026 14:25:11 +0000 (GMT) Received: from [9.52.200.195] (unknown [9.52.200.195]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 22 Apr 2026 14:25:11 +0000 (GMT) Message-ID: Date: Wed, 22 Apr 2026 16:25:10 +0200 Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 8/8] unwind: arm64: Use sframe to unwind interrupt frames To: Dylan Hatch , Roman Gushchin , Weinan Liu , Will Deacon , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Steven Rostedt , Catalin Marinas , Jiri Kosina Cc: Mark Rutland , Prasanna Kumar T S M , Puranjay Mohan , Song Liu , joe.lawrence@redhat.com, linux-toolchains@vger.kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Randy Dunlap , Heiko Carstens References: <20260421225200.1198447-1-dylanbhatch@google.com> <20260421225200.1198447-9-dylanbhatch@google.com> Content-Language: en-US From: Jens Remus Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20260421225200.1198447-9-dylanbhatch@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDIyMDEzOCBTYWx0ZWRfX2kvMUk3S+OC+ gqFoNEEhtnRg9VQeED2eCxTxjFLsq8P5YGGtBn3MZYMS6Ncda0aTLHMQxGdkwUD8gHCd4JHndY2 77je2Qk4nyZh0wv1gm2Rvtm0Qzr9rTpbqaPe0ijIH2Eipdd5hU4Z4XoNhDbNTuwkkEnV4NR/q7p u91zqcrMn5uyEUDuZ22tDazhCFYiGFonecYD7t+a3GBiqb/80VZ05XZV3jRUSyNkQOXVg3DuaRb 8y3WxBmDo+6aRRY1SmDkoxDe/fwu4n9T0wJHQ+6lZW4WFiKqtbfYU60+GHmaPeJCIfz0fO0cAXS OQpefQBPZvHofh84JCgHUuTcaXTTHrYJwF67Z4wzPQOm/fMlLgukqjeg+Fr3pPGSPoefZKRM9W8 p1X5IW/V5NQcz5iK+v5NfgDmg6OpHEfHfK3rK87mzhJzl+BZRGbu9SPoN0a94BSS889CSNLhllx fNBGFVnqJePkDtipz2A== X-Proofpoint-ORIG-GUID: b9RXQHKk6qny2EpuC5nOWztOld29cGVI X-Proofpoint-GUID: bIq9vOzF3LjsfNMvyWIsol4Xu-ODlMMw X-Authority-Analysis: v=2.4 cv=XMUAjwhE c=1 sm=1 tr=0 ts=69e8da4c cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=1XWaLZrsAAAA:8 a=yMhMjlubAAAA:8 a=cvgsuMldqgkNetmmUx0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-22_01,2026-04-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 priorityscore=1501 impostorscore=0 bulkscore=0 spamscore=0 lowpriorityscore=0 phishscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2604220138 On 4/22/2026 12:52 AM, Dylan Hatch wrote: > Add unwind_next_frame_sframe() function to unwind by sframe info if > present. Use this method at exception boundaries, falling back to > frame-pointer unwind only on failure. In such failure cases, the > stacktrace is considered unreliable. > > During normal unwind, prefer frame pointer unwind (for better > performance) with sframe as a backup. > > This change restores the LR behavior originally introduced in commit > c2c6b27b5aa14fa2 ("arm64: stacktrace: unwind exception boundaries"), > But later removed in commit 32ed1205682e ("arm64: stacktrace: Skip > reporting LR at exception boundaries") > > This can be done because the sframe data can be used to determine > whether the LR is current for the PC value recovered from pt_regs at the > exception boundary. > > Signed-off-by: Weinan Liu > Reviewed-by: Prasanna Kumar T S M > Signed-off-by: Dylan Hatch Reviewed-by: Jens Remus > --- > arch/arm64/include/asm/stacktrace/common.h | 6 + > arch/arm64/kernel/stacktrace.c | 246 +++++++++++++++++++-- > 2 files changed, 232 insertions(+), 20 deletions(-) Regards, Jens -- Jens Remus Linux on Z Development (D3303) jremus@de.ibm.com / jremus@linux.ibm.com IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM Data Privacy Statement: https://www.ibm.com/privacy/