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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Heiko Carstens , Vasily Gorbik , Ilya Leoshkevich Subject: [PATCH v14 09/19] unwind_user/sframe: Add support for outermost frame indication Date: Tue, 5 May 2026 14:17:08 +0200 Message-ID: <20260505121718.3572346-10-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260505121718.3572346-1-jremus@linux.ibm.com> References: <20260505121718.3572346-1-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-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA1MDExNCBTYWx0ZWRfXxs+poCAAGGNG 9Cfil+KpyvOWZ9eNrzo7p0DMXBFB8ddw/Z1jToIBMfBbF8gMOySE1DKHJWcGx47Gnac7WNDTiLo taNPOzcwB6Y8H6i8+1Pp4KPU6O2MUhFcCVbjeAmZURahIZN00aaJLb84ENmOF9mGSz+ks67MlTr rWIEqS/rjtv0J3bSVM1foQruayIKEyaxqJNlMCE5TMuK5spshFERy06ksgWNkD9fIzJybSvy8B3 ewWKJrKeorztqyjQ5ewij1YeHGFgGAgz/tqg52Kodd3NY4+bhgFswOXORS6TxaC/pufO+nVvMNa lvDsil9mJNjZR2uQAp/BAI5qeJIaCVQtOqPedhVQXoftsOrMd2EDrjECVrxiqBzenGD4t2J7Ncu CisLkq4sGFxUfvR9G99vD6Ar6DfjXVzC1S5QvuSL4Y/xZu+Qjhz09vn8ebdNyklOCvsy4Qs4CeP 2aUlUKu8+wPP2shbgRw== X-Proofpoint-GUID: efVzNbBCZREIKW4fO6gioglIN0VcT-tB X-Proofpoint-ORIG-GUID: BJSUMIXg6C-mMKI5aio-_pcfAq0a41Zm X-Authority-Analysis: v=2.4 cv=eu/vCIpX c=1 sm=1 tr=0 ts=69f9dfda cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=U72JrVpwKSe1qDC-WCIA:9 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=2026-05-05_02,2026-04-30_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 clxscore=1011 adultscore=0 suspectscore=0 malwarescore=0 bulkscore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605050114 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 c60aa527984a..9c755965ab83 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -218,7 +218,7 @@ 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 -EFAULT; if (cur + (dataword_count * dataword_size) > sec->fres_end) @@ -228,6 +228,17 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (fde_type != SFRAME_FDE_TYPE_DEFAULT) return -EFAULT; + 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--; @@ -248,6 +259,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (dataword_count) return -EFAULT; +done: fre->size = addr_size + 1 + (dataword_count * dataword_size); fre->ip_off = ip_off; fre->cfa_off = cfa_off; @@ -314,6 +326,7 @@ 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