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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 v16 09/20] unwind_user/sframe: Add support for outermost frame indication Date: Thu, 21 May 2026 16:25:35 +0200 Message-ID: <20260521142546.3908498-10-jremus@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260521142546.3908498-1-jremus@linux.ibm.com> References: <20260521142546.3908498-1-jremus@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 7rCW1Kl3JiSQvbDTjkeDjn_xdyYqbIvC X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0f15f6 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=U72JrVpwKSe1qDC-WCIA:9 X-Proofpoint-ORIG-GUID: 6oi19XfIJtW8o8a5alhlhnDu9LdS-yia X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIxMDE0MiBTYWx0ZWRfX+FQqoPmuqXsx spCH1rZ3/2BhMfree/aFtSJg3/02POcjFlCrrjiN0okatgPjd28Aeh3lymXLoDeWa+wtRSmOJcM I/EtAEa5ooi4R1zT4zKnIraBpiliFKoLGy/ADAq10WPQVulIhzdtF6nNG15bhdcoSk8b9+YLVQE Mw9OHusxDuB75oNGcBCOq5cHhmJ1f+VHBh/YhT4g4KLUC9FM7VtUtCkUkKSbQqY9tsl0ZSCKK7f xmkI0JOHIlFM2+4pDdULWxFDr2IwGa/FZU6EQotKYZh6+lagDGWe1fm5gfgpqxiROOzTrTXybLJ HUzvDUEc+hevIctj4eKTSAp2P1l6GFj8DuHsSm8xh2/4YLrSyPidA3VIG2cg5k3Qitn9nSaCcXG jGzkUPOpILjCHE+0QitaRHCBKjMS3jX7yYRgRc36dGgLUx9DjINpAvRtTcsgoWzSq/Mc0tGC9pw 6AOOqClSEssxylHmfSA== 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=2026-05-21_02,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210142 X-Rspam-User: X-Rspamd-Queue-Id: ABD3318000C X-Rspamd-Server: rspam04 X-Stat-Signature: xcfkgsat15s1yfdyofrc36k1bf83ixrb X-HE-Tag: 1779373572-630313 X-HE-Meta: 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 XALJ4MW9 UVb16ziEWEWtasVEkmhKZGICopGJi7oRaTOwAtNFUwOEvS6d5Cp6roLY3mOVyWlD+m2WHi7dDhxSnbO8kAYkO4ScZA6X3L28f6B8vMMKjk7lMWjuI7qF9/AizsZhuZdyowMd/3NNjoApFxirifyHFiCzuUGQWY6A5ktpd8CUVLiMb3BN2F6hjHkdhvul1u0iISbV35Tzi0kK12meaFmUpxp/mTqo6SLW+UwXXbjQAGfPf8d8tIlaAlF1dcNq7Sf907xAf694ONpJgKZIuS4p6RaJ0KeFwq6lDtD224xmwL8LLIr7THrrAR9U2ee75HbL2CEirTkajx+rPb+bWZVYGoyKBD3AzEECnVmvBg0fJOHzm2Mg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 2de29c836f6b..41ece3ca62a1 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -231,7 +231,7 @@ 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; fre_size = addr_size + 1 + (dataword_count * dataword_size); @@ -242,6 +242,17 @@ 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--; @@ -262,6 +273,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, if (dataword_count) return -EINVAL; +done: fre->size = fre_size; fre->ip_off = ip_off; fre->cfa_off = cfa_off; @@ -328,6 +340,7 @@ 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