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Thu, 21 May 2026 14:25:55 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 21 May 2026 14:25:55 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Steven Rostedt , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Dylan Hatch , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. 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 17/20] unwind_user/sframe: Separate reading of FRE from reading of FRE data words Date: Thu, 21 May 2026 16:25:43 +0200 Message-ID: <20260521142546.3908498-18-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-Spam-Details-Enc: AW1haW4tMjYwNTIxMDE0MiBTYWx0ZWRfX2bXFpxhRPDPH Zc7lbHxbLe/UJzeKtrvgFot5w+OnF6zmRVB3nwQqn16XdbVgYAN0fJW8Hak9lC1WDAMBP1Qr02s KC8SSZI1zh4AMnxafzBpituNpru1V912j6klurs0YGIXZv8x4BtkfpSXdb8rHKXWI0TlaA3Bu9y mkUPKMjoiZCu8vMBjSDRU5V+JRHgiDcmCZOSfbVLNirOjr8y1zRiufqpJkWqZlQI5KgS20DICEb jSSEskavsbCM6q7QwkD1KDbZJIH1KVAfbJFLS3RhUHIRI1BJwiEdDTLfEPWMk64Yfrx/ScAE7qO GgrCi4p1i9UV0uIGElHG74pDXawE36BlPiWLDHz5vmXgGWPjy8hTVzP8efVQkJfer9ErPjYtWP1 NeABBvnGu1l5rZwi9VCK8pJ1s6zTB5sW3oVrlNvNjEKlEGANUC6v5eVBEVPQGYwE2Xofi0NeYZD WQhygoIjVUsnBdILN5g== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0f15f9 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=RXKZOtKmAAAA:8 a=p_lxmaMNnb8s4VerTYQA:9 a=UFF3uGjEBZWolfm0k6KQ:22 X-Proofpoint-ORIG-GUID: drJApyXJj2y9hpl5tbDEjhRo_6IKVXYK X-Proofpoint-GUID: wGVBeE2STrhp9aFps6BixI2H6PEIK6K6 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 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210142 X-Stat-Signature: i1ib68cu6m198un37ypxr7o97toreapo X-Rspamd-Queue-Id: F09EF1C0008 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1779373602-192702 X-HE-Meta: U2FsdGVkX18uvxzJk2MaQ7Cju2dolmJFZy3rvCw9qUOJpzlIGSxi80TWBxB3iNf+//kM0VD/+ItEiyeSuibTuLuyuoy014oWg2uwULn0gEmL7XzuKHtvQ+enkoe9SwrdaqgZu+Wwcvh1t+eta5ZY7PM/O2MzzMb0O08AGu81d95oaYb3hnRSoPh2LbuU+CLDFPh+zhEt/oUG2kj30rColjfhq/Ur0dNPobbAhWJqM3ryOPghbQcZJ6TBhBXGESdF1+pReriWGpT7TMwZ5jPgKoShlbbWer+OtO5zjyD7H4LKhO6+KEXaJ+4uO0eYEo3eW1cqzPVWpXtj2cnWnI9G/w7N/fJjLnZAOH9H93ZBPUVix2ypospGxGRx8WoAfh8q3YUpHiTXH1vDXfzhLWM0xXWnXCzkmp2pCgbFk4aNtceKF/PE/qOybTC9mObKk6AUjy0f2R4eZyV54xz/BjMIdqychV3byE2zr8jtv83MG/3Xpwmr+THxrLzgOE6/t9O8EDOTVQhc2t7MzD5LmldXtmeXfFyl6hWRqntjXh9RIUlUtR6LVd4FOm38V6JSu/fbLrkmSGKjP6n2HVvD/5dilF7lOiezgaZwcfvxVjnXp9iS1ZsOhL8xJZMdjlNAzNeZNupgqx4/4RcPgPVXstSQ3UcE7rDNahQFRGT+UbB50/13ubGxuLFoXwH7gubv7Qe6c9sMSbLVY7Uk0pQXfT+KNOZIhFm0cBOmMWZ3ryU3mqueiMOiocTOwswLbdaz0lSm0aalSiV3nOMhWeWmgYbKIBRGWNzkGt7fAHR9/UTCyx6B6FY2bSdj8KdEEtbyy9bLZajCtng5x9drnBmtdDDzcbChjk9P9CREOsHcfYARe7PGcTwr0fixysCc3hE9QiTG1dPw1wC2WQP1EM+lqguLJwAu7x9pTG7tHrnTlxfg/KE7Utf1wHICOuzNIbNrolgjJNzMazt305OBAQHFnYz tydFMmnT TyiHrRAXt3CMVOnrWkmn1wBfqxRF0vkjBEj1ee/msV9J6NMrAKI40bP+hm9Qzr0p5j83+WyadxeMY8w+OMuoJKEGDWTzHt5yg/4riyDpIrk0+iovCpZSPMn0VtqTqVNigDGletosLfQLt+dZ5W9T0dzounrAOJEIBvk0V1kXitxGsY7mwsAoKilXHAkdd1qQ962DI1CjmEQp2AtP/2E7Y3QzMUzmsXrprXJNOmfLulFipRqSu2uZNx/1VMAYK31YoQB/aaEbUD0+6hdRdVDbO1bTOhbRBmrffo4GiGP0JnnGOKq71jMdRKYteo0CPS/jorH6b2O5nGskeDkZoOyCtHaNlNW55bfmIiF54ivWiVAYnppveSJxblLlEOWhK6cmJqg8qGosSzsMf0SSMemDyr9/fr8B4ctTjp5YdZOUztoSzrcY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: __find_fre() performs linear search for a matching SFrame FRE for a given IP. For that purpose it uses __read_fre(), which reads the whole FRE. That is the variable-size FRE structure as well as the trailing variable-length array of variable-size data words. For the search logic to skip over the FRE it would be sufficient to read the variable-size FRE structure only, which includes the count and size of data words. Add fields to struct sframe_fre_internal to store the FRE data word's address, count, and size. Change __read_fre() to read the variable- size FRE structure only and populate those new fields. Change __read_fre_datawords() to use those new fields. Change __find_fre() to use __read_fre_datawords() to read the FRE data words only after a matching FRE has been found. Introduce safe_read_fre_datawords() and use it in sframe_validate_section() to validate that the FRE data words. Reviewed-by: Indu Bhagat Signed-off-by: Jens Remus --- Notes (jremus): Changes in v15: - sframe_validate_section(): Fix format specifier for number of FREs in debug message. (Sashiko AI) Changes in v14: - Adjust to rename of SFRAME_FDE_TYPE_* and __read_default_fre_datawords(). - Update function name in debug message. kernel/unwind/sframe.c | 99 +++++++++++++++++++++++++++--------------- 1 file changed, 63 insertions(+), 36 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index b623dca072da..7f439600b0f0 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -39,6 +39,9 @@ struct sframe_fre_internal { u32 fp_ctl; s32 fp_off; u8 info; + unsigned long dw_addr; + unsigned char dw_count; + unsigned char dw_size; }; DEFINE_STATIC_SRCU(sframe_srcu); @@ -207,11 +210,11 @@ static __always_inline int __find_fde(struct sframe_section *sec, static __always_inline int __read_default_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { + unsigned char dataword_count = fre->dw_count; + unsigned char dataword_size = fre->dw_size; + unsigned long cur = fre->dw_addr; s32 cfa_off, ra_off, fp_off; unsigned int cfa_regnum; @@ -253,11 +256,11 @@ __read_default_fre_datawords(struct sframe_section *sec, static __always_inline int __read_flex_fde_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { + unsigned char dataword_count = fre->dw_count; + unsigned char dataword_size = fre->dw_size; + unsigned long cur = fre->dw_addr; u32 cfa_ctl, ra_ctl, fp_ctl; s32 cfa_off, ra_off, fp_off; @@ -325,24 +328,34 @@ __read_flex_fde_fre_datawords(struct sframe_section *sec, static __always_inline int __read_fre_datawords(struct sframe_section *sec, struct sframe_fde_internal *fde, - unsigned long cur, - unsigned char dataword_count, - unsigned char dataword_size, struct sframe_fre_internal *fre) { unsigned char fde_type = SFRAME_V3_FDE_TYPE(fde->info2); + unsigned char dataword_count = fre->dw_count; + + if (!dataword_count) { + /* + * A FRE without datawords indicates an outermost + * frame. Zero-initialize CFA, RA, and FP location + * info, except for the CFA control word, so that + * neither sframe_init_cfa_rule_data() nor + * sframe_init_rule_data() fail. + */ + fre->cfa_ctl = (SFRAME_REG_SP << 3) | 1; /* regnum=SP, deref_p=0, reg_p=1 */ + fre->cfa_off = 0; + fre->ra_ctl = 0; + fre->ra_off = 0; + fre->fp_ctl = 0; + fre->fp_off = 0; + + return 0; + } switch (fde_type) { case SFRAME_FDE_TYPE_DEFAULT: - return __read_default_fre_datawords(sec, fde, cur, - dataword_count, - dataword_size, - fre); + return __read_default_fre_datawords(sec, fde, fre); case SFRAME_FDE_TYPE_FLEX: - return __read_flex_fde_fre_datawords(sec, fde, cur, - dataword_count, - dataword_size, - fre); + return __read_flex_fde_fre_datawords(sec, fde, fre); default: return -EINVAL; } @@ -385,26 +398,11 @@ static __always_inline int __read_fre(struct sframe_section *sec, fre->size = addr_size + 1 + (dataword_count * dataword_size); fre->ip_off = ip_off; fre->info = info; + fre->dw_addr = cur; + fre->dw_count = dataword_count; + fre->dw_size = dataword_size; - if (!dataword_count) { - /* - * A FRE without datawords indicates an outermost - * frame. Zero-initialize CFA, RA, and FP location - * info, except for the CFA control word, so that - * neither sframe_init_cfa_rule_data() nor - * sframe_init_rule_data() fail. - */ - fre->cfa_ctl = (SFRAME_REG_SP << 3) | 1; /* regnum=SP, deref_p=0, reg_p=1 */ - fre->cfa_off = 0; - fre->ra_ctl = 0; - fre->ra_off = 0; - fre->fp_ctl = 0; - fre->fp_off = 0; - - return 0; - } - - return __read_fre_datawords(sec, fde, cur, dataword_count, dataword_size, fre); + return 0; Efault: return -EFAULT; @@ -527,6 +525,10 @@ static __always_inline int __find_fre(struct sframe_section *sec, return -EINVAL; fre = prev_fre; + ret = __read_fre_datawords(sec, fde, fre); + if (ret) + return ret; + ret = sframe_init_cfa_rule_data(&frame->cfa, fre->cfa_ctl, fre->cfa_off); if (ret) return ret; @@ -610,6 +612,20 @@ static int safe_read_fre(struct sframe_section *sec, return ret; } +static int safe_read_fre_datawords(struct sframe_section *sec, + struct sframe_fde_internal *fde, + struct sframe_fre_internal *fre) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret = __read_fre_datawords(sec, fde, fre); + user_read_access_end(); + return ret; +} + static int sframe_validate_section(struct sframe_section *sec) { struct sframe_fde_internal fde; @@ -648,6 +664,17 @@ static int sframe_validate_section(struct sframe_section *sec) fde.rep_size); return ret; } + ret = safe_read_fre_datawords(sec, &fde, &fre); + if (ret) { + dbg_sec("FDE %u: safe_read_fre_datawords(%u) failed\n", i, j); + dbg_sec("FDE: func_addr:%#lx func_size:%#x fda_off:%#x fres_off:%#x fres_num:%u info:%u info2:%u rep_size:%u\n", + fde.func_addr, fde.func_size, + fde.fda_off, + fde.fres_off, fde.fres_num, + fde.info, fde.info2, + fde.rep_size); + return ret; + } if (j && fre.ip_off <= prev_ip_off) { dbg_sec("FDE %u: FRE %u not sorted\n", i, j); -- 2.51.0