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Peter Anvin" , Mathieu Desnoyers , Kees Cook , Sam James Cc: Jens Remus , bpf@vger.kernel.org, linux-mm@kvack.org, Namhyung Kim , Andrii Nakryiko , "Jose E. Marchesi" , Beau Belgrave , Florian Weimer , "Carlos O'Donell" , Masami Hiramatsu , Jiri Olsa , Arnaldo Carvalho de Melo , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v15 09/20] unwind_user/sframe: Add support for outermost frame indication Date: Wed, 20 May 2026 17:39:53 +0200 Message-ID: <20260520154004.3845823-10-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260520154004.3845823-1-jremus@linux.ibm.com> References: <20260520154004.3845823-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0dd5e1 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=U72JrVpwKSe1qDC-WCIA:9 X-Proofpoint-ORIG-GUID: RutorrHK_Yh961JRGNUS1hvnwjZkw88C X-Proofpoint-GUID: XnZrEE4_Iky6X02Y2pC9TJ5PPqyzpqIn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE1MSBTYWx0ZWRfX1OqTSBjg6JuQ 3CYMiUWNmccKjjzBUq2FHOZJTDO7VV9RUQtDZ/UosD6cXC4wirTJjKWlbMgrl57yNKjZx4nqukq CUEyyWpoI+g96MdSRvblOL3fNjCPUGmjXY8swPhuIFkQLVXheAquLoSsWfWMx3R6TTOvnx3HXEi gTK2ZGHp2EO4VVybVguhAvAOyiXxbjjRblupu5eGISleIYUFA8D+1pMybPtQ7IOkPP/lVSPpBJ+ KdgYqWAWsxR62CmXaPjcU7qj0KlR791ABFSU5jlans+thlIpN2KGruDpNnwhNS4C5i4fU2fxluh hmge4nC/w4oV7pFW7faXGslWKLCMvhTmSL8q5nnhRvinUilCZYfHgBCDucTfgEKIMiDgejCKPP7 njDNzY36T8g9hnYZU71eXoCzez16WpGBrTeb5i8io6vVApLmm8HCKExgY84mMF4IT50TmosB2E/ C5c1EoJcDHhQugNIg7w== 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=2026-05-20_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200151 SFrame may represent an undefined return address (RA) as SFrame FRE without any offsets as indication for an outermost frame. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- 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 a38f50a36363..f723c1a32f90 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -230,7 +230,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, UNSAFE_GET_USER_INC(info, cur, 1, Efault); dataword_count = SFRAME_V3_FRE_DATAWORD_COUNT(info); dataword_size = dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE(info)); - if (!dataword_count || !dataword_size) + if (!dataword_size) return -EINVAL; if (cur + (dataword_count * dataword_size) > sec->fres_end) @@ -240,6 +240,17 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (fde_type != SFRAME_FDE_TYPE_DEFAULT) return -EINVAL; + if (!dataword_count) { + /* + * A FRE without data words indicates RA undefined / + * outermost frame. + */ + cfa_off = 0; + ra_off = 0; + fp_off = 0; + goto done; + } + UNSAFE_GET_USER_INC(cfa_off, cur, dataword_size, Efault); dataword_count--; @@ -260,6 +271,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (dataword_count) return -EINVAL; +done: fre->size = addr_size + 1 + (dataword_count * dataword_size); fre->ip_off = ip_off; fre->cfa_off = cfa_off; @@ -326,6 +338,7 @@ static __always_inline int __find_fre(struct sframe_section *sec, frame->ra_off = fre->ra_off; frame->fp_off = fre->fp_off; frame->use_fp = SFRAME_V3_FRE_CFA_BASE_REG_ID(fre->info) == SFRAME_BASE_REG_FP; + frame->outermost = SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info); return 0; } diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h index fc2908e92c7b..ed111fd0d702 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) == 0) #endif /* _SFRAME_H */ -- 2.51.0