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Tue, 21 Apr 2026 08:27:45 +0000 (GMT) Received: from [9.52.200.195] (unknown [9.52.200.195]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 21 Apr 2026 08:27:45 +0000 (GMT) Message-ID: <9115d2bc-781b-4e5f-9772-c0ebeecac91b@linux.ibm.com> Date: Tue, 21 Apr 2026 10:27:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 04/18] unwind_user/sframe: Add support for reading .sframe contents To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, Steven Rostedt Cc: Josh Poimboeuf , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , "Jose E. 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Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Heiko Carstens , Vasily Gorbik , "Steven Rostedt (Google)" , Indu Bhagat References: <20260127150554.2760964-1-jremus@linux.ibm.com> <20260127150554.2760964-5-jremus@linux.ibm.com> Content-Language: en-US From: Jens Remus Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20260127150554.2760964-5-jremus@linux.ibm.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-ORIG-GUID: 1goWuCKfC-7KiyC8K84-VTn1qdBVnTzk X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDIxMDA4MCBTYWx0ZWRfXx0veQ28IaQW6 fPpGKE4AGs52FLXRq6Os3Xi7WV4PA62uhAW5W5FYHNjTyGzvxoBYcO+upsEji4XkUq45iwHMnPa 5uXe82pmmIHwh8j+XiOtB3QJgqbgEAJ3/nZGi3mxK1KJ8xn//G3zAIbnMl7vegYyhLS6kqtnFKl UU2LTeYDnNT9Ug9l0P9gDNLYsSWZdKb/n/eZpr/dZGX/UWb9W7Iw7+6d+M3hOlEbUTgFoPPTf/2 FrAHbNm5p95qGcAThxOl52GrNE+iDowxuLDF6IRTKCHY2sv+z/Zumc5muCysXEGiyY2cVHjB199 jr78obbMbd8xZJFoIlqxqqucb3hiNVm6TM/4K4Nc3rhgwrnMGBZ8FwBTnptCyruvZ4upXzRvruZ kztMNtG3p4Wrl882vpsH1sm+AsvYQMTYbE4Y8O0wTJn8ajhxRFAYSvMhcqqUW+7D4yplyA5jpbq mezHHgL1OpRdsRhZwTA== X-Authority-Analysis: v=2.4 cv=XLYAjwhE c=1 sm=1 tr=0 ts=69e7350a cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=rIsWgEjAf_fsY0NmbdQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: GDOmWqtYOiKgBotIL32-m-aTBWQC6JcH 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=2026-04-21_01,2026-04-20_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 impostorscore=0 spamscore=0 adultscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604210080 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 3588B40004 X-Stat-Signature: xfma8syxmg8iw3ebuqrdeab3zumfetu5 X-Rspam-User: X-HE-Tag: 1776760103-129762 X-HE-Meta: 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 mfhcK5kB gfb9gfG8lN0qa3AHxa3soKijI8pF3gqUGqjjJEPUONxVlHOI4tDxJJ673Hhm6bbdBWVzsUqktiwUujqh90Gs28h5VttGBPypS8vn33IKVkNLL2EcPWueEGyc2sZNF46efiS+clSYZIr4l0vUEFY4txEuQSsyok0gdQFjAFJlRHH6O8jnEoCDY95MICshDB5YPgVYgMAxWoj9mnAPRbLy0VEWCOpdn7dXHSdnfu6KeA18DeQvuoy3zgPaj26GbmFQ8f8tjplqcK07QOWMHBTPQcTnAnFLmp9k1mCMSmHhukVIJYy8CMaDxJZBzot+gJBx83WjyLRo2rFqM6atrbJP06l69AYqgqZVX4e1aaSvrggwZsvWSa3G1k8f6O9YYbstcy3D+ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 1/27/2026 4:05 PM, Jens Remus wrote: > From: Josh Poimboeuf > > In preparation for using sframe to unwind user space stacks, add an > sframe_find() interface for finding the sframe information associated > with a given text address. > > For performance, use user_read_access_begin() and the corresponding > unsafe_*() accessors. Note that use of pr_debug() in uaccess-enabled > regions would break noinstr validation, so there aren't any debug > messages yet. That will be added in a subsequent commit. > > Link: https://lore.kernel.org/all/77c0d1ec143bf2a53d66c4ecb190e7e0a576fbfd.1737511963.git.jpoimboe@kernel.org/ > Link: https://lore.kernel.org/all/b35ca3a3-8de5-4d32-8d30-d4e562f6b0de@linux.ibm.com/ > > [ Jens Remus: Add initial support for SFrame V3 (limited to regular > FDEs). Add support for PC-relative FDE function start offset. Simplify > logic by using an internal FDE representation. Rename struct sframe_fre > to sframe_fre_internal to align with struct sframe_fde_internal. > Cleanup includes. Fix checkpatch errors "spaces required around that > ':'". ] > diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c > +static __always_inline int __read_fde(struct sframe_section *sec, > + unsigned int fde_num, > + struct sframe_fde_internal *fde) > +{ > + unsigned long fde_addr, fda_addr, func_addr; > + struct sframe_fde_v3 _fde; > + struct sframe_fda_v3 _fda; > + > + fde_addr = sec->fdes_start + (fde_num * sizeof(struct sframe_fde_v3)); > + unsafe_copy_from_user(&_fde, (void __user *)fde_addr, > + sizeof(struct sframe_fde_v3), Efault); > + > + func_addr = fde_addr + _fde.func_start_off; > + if (func_addr < sec->text_start || func_addr > sec->text_end) sec->text_end points after the last byte of the .text section. Therefore the check for whether FDE function start address is within the section must be: if (func_addr < sec->text_start || func_addr >= sec->text_end) > + return -EINVAL; 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/