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Marchesi" , Beau Belgrave , Linus Torvalds , Andrew Morton , Florian Weimer , Kees Cook , "Carlos O'Donell" , Sam James , Dylan Hatch , Borislav Petkov , Dave Hansen , David Hildenbrand , "H. Peter Anvin" , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , Heiko Carstens , Vasily Gorbik Subject: [PATCH v13 08/18] unwind_user/sframe: Add support for outermost frame indication Date: Tue, 27 Jan 2026 16:05:43 +0100 Message-ID: <20260127150554.2760964-9-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260127150554.2760964-1-jremus@linux.ibm.com> References: <20260127150554.2760964-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Z4vh3XRA c=1 sm=1 tr=0 ts=6978d45d cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=7d_E57ReAAAA:8 a=JfrnYn6hAAAA:8 a=yPCof4ZbAAAA:8 a=mDV3o1hIAAAA:8 a=yMhMjlubAAAA:8 a=VnNF1IyMAAAA:8 a=Z4Rwk6OoAAAA:8 a=20KFwNOVAAAA:8 a=7mOBRU54AAAA:8 a=mFg4y33aAicYmUfzDuoA:9 a=jhqOcbufqs7Y1TYCrUUU:22 a=1CNFftbPRP8L7MoqJWF3:22 a=HkZW87K1Qel5hWWM3VKY:22 a=wa9RWnbW_A1YIeRBVszw:22 X-Proofpoint-GUID: KlXhgSsl-7XYGr8sEfIy1wcmIpHJAtvp X-Proofpoint-ORIG-GUID: 1nm0Z9teSyeP7GTrC8S6VI-9JvDkzbHB X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTI3MDEyMSBTYWx0ZWRfX8ehchMl53yaJ fhvCTCx2yZ+p/TGN5+RQxrq9+j9wt8NoOUFDFh4LaSJ8mHgL4MfxPbe1jiMBkO2WgFVHakS/7r4 M/vG8tmc6/ZZtysxHnzyfD2QBCzYPHmtaDf8z6PoOSaGsRPGux9TIHoDib4brteX4Kl7RxoOko3 R/BboGphlfMIzq4TYydGBoXM6RQzK9f4qNX3l9SXTf11tarMJYJMd1F3Gzz8JjuoHTmxKCsAKSj Bhqx3M2ObqttbbAkyce1w/34RocYLgP/kLgpIm0eWsYQGgQJppOZ7G3QXRJtMQsmKPeOGpPLt09 5p1uRo/I2tKfrbhz4qa+cwhw2kOhG3IkbrcIJxw3zl7zZ8E9bo90ijYt9EA1yBlHYYHRmBkfO/R MpszybXEApyTC3gxchB+ndVRNUZs8XNDhDXZA57uFhC0OD/V/IT7GHTkPTs0mIAvqbZDzp7ItNT b/PaEexVcRASurcbwHg== 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=2026-01-27_03,2026-01-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 phishscore=0 priorityscore=1501 bulkscore=0 adultscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601270121 Content-Type: text/plain; charset="utf-8" SFrame may represent an undefined return address (RA) as SFrame FRE without any offsets as indication for an outermost frame. Cc: Steven Rostedt Cc: Josh Poimboeuf Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Jiri Olsa Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Thomas Gleixner Cc: Andrii Nakryiko Cc: Indu Bhagat Cc: "Jose E. Marchesi" Cc: Beau Belgrave Cc: Jens Remus Cc: Linus Torvalds Cc: Andrew Morton Cc: Florian Weimer Cc: Sam James Cc: Kees Cook Cc: "Carlos O'Donell" Signed-off-by: Jens Remus --- Notes (jremus): Changes in v13: - Use SFRAME_V3_FRE_RA_UNDEFINED_P() instead of struct sframe_fre_internal.ra_undefined field. - Reduce indentation of assignments. kernel/unwind/sframe.c | 15 ++++++++++++++- kernel/unwind/sframe.h | 1 + 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 9b3779924395..6004b43aac34 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -218,7 +218,7 @@ static __always_inline int __read_fre(struct sframe_sec= tion *sec, UNSAFE_GET_USER_INC(info, cur, 1, Efault); dataword_count =3D SFRAME_V3_FRE_DATAWORD_COUNT(info); dataword_size =3D dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE= (info)); - if (!dataword_count || !dataword_size) + if (!dataword_size) return -EFAULT; =20 if (cur + (dataword_count * dataword_size) > sec->fres_end) @@ -228,6 +228,17 @@ static __always_inline int __read_fre(struct sframe_se= ction *sec, if (fde_type !=3D SFRAME_FDE_TYPE_REGULAR) return -EFAULT; =20 + if (!dataword_count) { + /* + * A FRE without data words indicates RA undefined / + * outermost frame. + */ + cfa_off =3D 0; + ra_off =3D 0; + fp_off =3D 0; + goto done; + } + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); dataword_count--; =20 @@ -248,6 +259,7 @@ static __always_inline int __read_fre(struct sframe_sec= tion *sec, if (dataword_count) return -EFAULT; =20 +done: fre->size =3D addr_size + 1 + (dataword_count * dataword_size); fre->ip_off =3D ip_off; fre->cfa_off =3D cfa_off; @@ -314,6 +326,7 @@ static __always_inline int __find_fre(struct sframe_sec= tion *sec, frame->ra_off =3D fre->ra_off; frame->fp_off =3D fre->fp_off; frame->use_fp =3D SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) =3D=3D SFRAME= _BASE_REG_FP; + frame->outermost =3D SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); =20 return 0; } diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h index 07a2e99855f9..3fcc15534e5a 100644 --- a/kernel/unwind/sframe.h +++ b/kernel/unwind/sframe.h @@ -77,5 +77,6 @@ struct sframe_fda_v3 { #define SFRAME_V3_FRE_DATAWORD_COUNT(info) (((info) >> 1) & 0xf) #define SFRAME_V3_FRE_DATAWORD_SIZE(info) (((info) >> 5) & 0x3) #define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info) (((info) >> 7) & 0x1) +#define SFRAME_V3_FRE_RA_UNDEFINED_P(info) (SFRAME_V3_FRE_DATAWORD_COUNT(= info) =3D=3D 0) =20 #endif /* _SFRAME_H */ --=20 2.51.0