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Tue, 10 Feb 2026 16:46:34 +0000 (GMT) Message-ID: <15f2af3b-be33-46fc-b972-6b8e7e0aa52e@linux.ibm.com> Date: Tue, 10 Feb 2026 17:46:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 6/6] x86/vdso: Enable sframe generation in VDSO To: "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, Josh Poimboeuf , Steven Rostedt Cc: Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Arnaldo Carvalho de Melo , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Linus Torvalds , Andrew Morton , Florian Weimer , Kees Cook , "Carlos O'Donell" , Sam James , Dylan Hatch , Borislav Petkov , Dave Hansen , David Hildenbrand , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Heiko Carstens , Vasily Gorbik , "Steven Rostedt (Google)" References: <20260206193642.1580787-1-jremus@linux.ibm.com> <20260206193642.1580787-7-jremus@linux.ibm.com> Content-Language: en-US From: Jens Remus Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20260206193642.1580787-7-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-Spam-Details-Enc: AW1haW4tMjYwMjEwMDEzNiBTYWx0ZWRfXx0hBg5sfg+Sm RCuatqOyNDSemteUA5F+r4Ge2cM0/zQOT5n/ZqVCnhyWG/QDD8i2JZhH1g/2iNZAlUWMjFcAQVv pLQReX4/gIcOywzLhe9vqmurQ5b392gkE0KkGwkYXtgA5vQqorSZO05XXfmGA7F3cHoV7IuOb0W SVobFFKAR0XUxdXlnR4vIoqeLG8O3jVoiY7hQ6NzvemQWA+EtgEVvD5AlP3e/vVG9Qaa3drVQy9 /sgxePwtuEN1f8WRa82RYtNS9SVWFZlrfXcicv/IhhD80u3BXV48SQ2VkPvaBjKDUA9TbF4+KFb tMseD+WNlwQAAB+vVNDVm8wRqwnIolO5Etlys3u7FIrx9imuqvSssMtnTBNkfnBTmdc43e0kyV8 9aIDMBhrzcmT5khDY9al2AMmIMlQjsBL1iF949YpEinx01JHeY8jM/0sXyRV+4rbE/yYRPRyR05 564StLrk5fLK2GaTHmw== X-Proofpoint-ORIG-GUID: lFUhbotL6mZHHQBIGQHNWFr4iFqXQvoQ X-Proofpoint-GUID: yXXBPSDw6CtLkz2VIBzGSNLoMPEAqhQX X-Authority-Analysis: v=2.4 cv=O+Y0fR9W c=1 sm=1 tr=0 ts=698b60f1 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=meVymXHHAAAA:8 a=1YTvd-3GSpCLN8fQQIoA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=2JgSa4NbpEOStq-L5dxp:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-10_01,2026-02-10_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 adultscore=0 malwarescore=0 impostorscore=0 bulkscore=0 clxscore=1015 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602100136 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3A8F41C0004 X-Stat-Signature: mqh7mstb56cz7c44x43ua6ta1fqaddac X-Rspam-User: X-HE-Tag: 1770742031-338046 X-HE-Meta: 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 VAvRTmxe K7ywG4OJQl684Cmy4qVvlLjWBmXeOBszXlWq+AEU0QT+MZ7LleOrvGh4sc2jHifPtqcFfGnzdfibYHCjC25Gfj8CAH4+61NqNvU5yzSFgwieVsXAtZEegPcVStMqR+Ck6b72yu8GVG6AUo2GVVlAoRi0udjHHW+TgIIPXfLuHK8XnN56FHb9UdWavVgYuqeBxXrLmWcjsR2dvO9xoCULdyx9zztzhKa8/je+/UwzMpXz1k0w6pf1wO8mG3pNCZpP66RnTxrbRnn5R4V9F2qOwM1KkCAogWu9ttL+uYN1A+N/TJwXxVr32eC/F+jf53adROzrY22uWG+frDZgqLoQYKpCGNSadIj5VgCpXZIZ4RtZqHUrT40wd+ic107jlNSLn47/KbMqyWiTdHCs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/6/2026 8:36 PM, Jens Remus wrote: > From: Josh Poimboeuf > > Enable sframe generation in the VDSO library so kernel and user space > can unwind through it. > > SFrame isn't supported for x32 or x86-32. Discard .sframe sections for > those VDSOs. > > [ Jens Remus: Add support for SFrame V3. Prevent GNU_SFRAME program > table entry to empty .sframe section. ] > > Signed-off-by: Josh Poimboeuf > Signed-off-by: Steven Rostedt (Google) > Signed-off-by: Jens Remus > diff --git a/arch/Kconfig b/arch/Kconfig > @@ -479,6 +479,13 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH > It uses the same command line parameters, and sysctl interface, > as the generic hardlockup detectors. > > +config AS_SFRAME > + bool > + > +config AS_SFRAME3 > + def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,-Wa$(comma)--gsframe-3) Above tests whether the assembler supports --gsframe-3 to generate .sframe in SFrame V3 format. GNU assembler only supports to generate SFrame for x86-64. If the assembler is built for i386 (x86-32) the test will fail unless option --64 is specified. I wonder whether that could happen in (the rather hypothetical?) case, when the kernel is cross built for x86-64 on i386? Should this therefore be changed to the following? config AS_SFRAME_64 def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,$(m64-flag) -Wa$(comma)--gsframe) An alternative would be to enable as-instr64 to accept an optional flag operand, similar to as-instr, and use as-instr64 instead of as-instr. Or is this not required, as in a cross build for 64-bit on a 32-bit platform (or inverse) a respective cross toolchain is a prerequisite and the m64-flag (or m32-flag) is not used? I tried to simulate this using docker and an i386 image and then using the i386 tool in the container to switch "uname -m" to "i686". But both of my following attempts to build for x86-64 on i386 fail with fixdep not found: $ docker run -it --rm -v "$HOME/linux:$HOME/linux" --platform i386 public.ecr.aws/docker/library/debian:13.3 # sed -i -s 's/^Types: deb/& deb-src/' /etc/apt/sources.list.d/debian.sources # apt update # apt -y build-dep linux # make mrproper # i386 make ARCH=x86_64 defconfig # i386 make ARCH=x86_64 arch/x86/entry/vdso/ # make mrproper # apt -y install gcc-x86-64-linux-gnu # i386 make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- defconfig # i386 make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- arch/x86/entry/vdso/ > + select AS_SFRAME > + > config UNWIND_USER > bool > diff --git a/arch/x86/entry/vdso/vdso64/Makefile b/arch/x86/entry/vdso/vdso64/Makefile > @@ -14,6 +14,7 @@ vobjs-$(CONFIG_X86_SGX) += vsgx.o > > # Compilation flags > flags-y := -DBUILD_VDSO64 -m64 -mcmodel=small > +flags-$(CONFIG_AS_SFRAME3) += -Wa,--gsframe-3 flags-$(CONFIG_AS_SFRAME3_64) += -Wa,--gsframe-3 > > # The location of this include matters! > include $(src)/../common/Makefile.include Thanks and 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/