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Wed, 5 Feb 2025 13:56:38 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B6BDA2004B; Wed, 5 Feb 2025 13:56:38 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C4B3C20043; Wed, 5 Feb 2025 13:56:37 +0000 (GMT) Received: from [9.171.165.127] (unknown [9.171.165.127]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 5 Feb 2025 13:56:37 +0000 (GMT) Message-ID: <9a726893-4973-40f0-a2b5-63b2036e2e4e@linux.ibm.com> Date: Wed, 5 Feb 2025 14:56:36 +0100 Precedence: bulk X-Mailing-List: linux-toolchains@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 17/39] unwind_user/sframe: Add support for reading .sframe headers To: Josh Poimboeuf , Andrii Nakryiko Cc: Indu Bhagat , x86@kernel.org, Peter Zijlstra , Steven Rostedt , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, Mark Brown , linux-toolchains@vger.kernel.org, Jordan Rome , Sam James , linux-trace-kernel@vger.kernel.org, Mathieu Desnoyers , Florian Weimer , Andy Lutomirski , Masami Hiramatsu , Weinan Liu References: <20250124192159.ypvqwoqjvhasamev@jpoimboe> <47f1e244-992f-44fe-a0a5-6c271e9c719e@oracle.com> <20250129020249.owmklacvuvss7z7n@jpoimboe> From: Jens Remus Content-Language: en-US Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20250129020249.owmklacvuvss7z7n@jpoimboe> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: FoeKv70vsKAME6cJt7w4lE4LUboDqNi8 X-Proofpoint-ORIG-GUID: UmYpWnbvFFL0sEps-RqOV8VpRzmTO1NE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-05_05,2025-02-05_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 mlxlogscore=999 suspectscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 mlxscore=0 clxscore=1015 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2501170000 definitions=main-2502050108 On 29.01.2025 03:02, Josh Poimboeuf wrote: > Note FDEs aren't even needed here as the unwinder doesn't need to know > when a function begins/ends. The only info needed by the unwinder is > just the fre_data struct. So a simple binary search of fres[] is all > that's really needed. In SFrame V2 FDEs specify ranges bound by function start address and length. FREs in contrast specify open ranges bounded by start address. Their effect ends either with the next FRE becoming into effect or when their FDE range ends. This concept enables holes in the .text section which do not have any valid FDE/FRE information associated. Your proposal lacks some sort of mechanism to replicate those holes. It could be FDEs with a flag (or no offsets?) that specifies their range has no valid information. Regards, Jens -- Jens Remus Linux on Z Development (D3303) +49-7031-16-1128 Office jremus@de.ibm.com IBM IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Böblingen; Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM Data Privacy Statement: https://www.ibm.com/privacy/