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Wed, 7 Oct 2026 11:41:59 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with SMTP; Wed, 7 Oct 2026 11:41:59 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 55669) id 99253160B5C; Wed, 07 Oct 2026 13:41:58 +0200 (CEST) From: Alexander Gordeev To: Gerald Schaefer , Heiko Carstens , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda , Andrey Ryabinin Cc: Muhammad Usama Anjum , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: [PATCH v8 15/15] s390/mm: Lazy MMU mode sanitizer Date: Wed, 7 Oct 2026 13:41:58 +0200 Message-ID: <1890ee88ced60e0d03d88e681b7e6dde6a6158fa.1791365932.git.agordeev@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: 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-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: gcCe8F3CQ5BCZYsIAkt8nvvQAh87lCOb X-Proofpoint-GUID: ZhGgR0h0gzeUPkR7w8xgqgrq71GTCE_W X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA3MDA0NiBTYWx0ZWRfX2yDlotAE55ev Koli4pRdmy8NExpXmDPFt2mBOi89UIWyl6LTixPxnLHU2b7yjeSbZWgw9Krgack4yJqW9rPypkl Q2T2E5Y38Fd/keU9WhSWketmZ5RJzgo= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA3MDA0NiBTYWx0ZWRfX6LcQRnfiB2Q8 SiN0S//pA4DUcuKYAicXzk6Kc6YCJXL9rLaw2I5Z36fQrR2Bxbpy/5hULWW9ovj+y8hIFUFSxYQ qithfL9FiM+ca0cj6gFa4t+S3ebjAy2TyWvT3x5z+Fvi3CnCRczowSumBVMf/iAozgP+CamDQ3J yVOlpjw8cdLznaqJdT37l83Y5yS2Xr/a7fvOBw4v0YRdBJGjgveOKIvpmPW8Z2PHCXOrBP7j0Qr HFAgMwsMmKLLZMUkC1/uBsW6afu3BbSXNNSdPx2a2k8NDWE8X/xlqPe5vnUxUXigDhZo+zLXc2f snko2x/URfphXnGpuk3sBz/p4CAB61jlIn28UunVhpP8dws1TaBCOzhZBsABpVjT3n9Xf3o+vnv osOE/Vp1H1I5+N+0rXqBUznKzcURLQ3vuYA3FY4N/5fwthoiVOZMj9tFINKAc3Mbk96Ieypt8cI uNQJhDqV/qAXNxLOQFw== X-Authority-Analysis: v=2.4 cv=eYeo7LEH c=1 sm=1 tr=0 ts=6ac6300c cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=DuHJb5c9rUSq-GGRdagA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-07_04,2026-10-06_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 clxscore=1015 spamscore=0 malwarescore=0 priorityscore=1501 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610070046 Detect PTE entries access in lazy MMU mode by means other than set_pte() and ptep_get() primitives, which would be a read hazard. The access to kasan shadow memory from ptep_get_lockless() mistakenly hits invalid access in case a concurrent lazy MMU access to the same PTE is happening. To avoid that disable instrumentation for ptep_get_lockless() altogether. Suggested-by: Ilya Leoshkevich Signed-off-by: Alexander Gordeev --- arch/s390/include/asm/pgtable.h | 6 ++++++ arch/s390/mm/lazy_mmu.c | 27 +++++++++++++++++++++++---- 2 files changed, 29 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgta= ble.h index decce76fac74..47f0adfc1029 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1063,6 +1063,12 @@ static inline void set_pte(hw_pte_t *ptep, pte_t p= te) __set_pte(ptep, pte); } =20 +#define ptep_get_lockless ptep_get_lockless +static inline __no_sanitize_address pte_t ptep_get_lockless(hw_pte_t *pt= ep) +{ + return __pte_from_hw(READ_ONCE(*ptep)); +} + static inline pte_t __ptep_get(hw_pte_t *ptep) { return __pte_from_hw(READ_ONCE(*ptep)); diff --git a/arch/s390/mm/lazy_mmu.c b/arch/s390/mm/lazy_mmu.c index 8c1a62f23736..e29afa081061 100644 --- a/arch/s390/mm/lazy_mmu.c +++ b/arch/s390/mm/lazy_mmu.c @@ -65,10 +65,13 @@ static int invalidate_pte_range(struct mm_struct *mm,= unsigned long addr, } =20 static void set_pte_range(struct mm_struct *mm, unsigned long addr, - hw_pte_t *ptep, hw_pte_t *end, pte_t *cache) + hw_pte_t *start, hw_pte_t *end, pte_t *cache) { - int i, nr_ptes; + int nr_ptes, nr_total =3D end - start; + hw_pte_t *ptep =3D start; + int i; =20 + kasan_unpoison_pte(start, nr_total); while (ptep < end) { nr_ptes =3D invalidate_pte_range(mm, addr, ptep, end); =20 @@ -79,6 +82,7 @@ static void set_pte_range(struct mm_struct *mm, unsigne= d long addr, =20 addr +=3D nr_ptes * PAGE_SIZE; } + kasan_poison_pte(start, nr_total); } =20 static void enter_ipte_norange(void) @@ -98,6 +102,7 @@ static void enter_ipte_range(struct mm_struct *mm, unsigned long addr, unsigned long end, hw_pte_t *pte) { struct ipte_range *range; + unsigned int nr_ptes; =20 if (!static_branch_likely(&lazy_mmu_enabled)) return; @@ -116,6 +121,9 @@ static void enter_ipte_range(struct mm_struct *mm, range->base_end =3D end; range->base_pte =3D pte; =20 + nr_ptes =3D (range->base_end - range->base_addr) / PAGE_SIZE; + kasan_poison_pte(range->base_pte, nr_ptes); + local_bh_enable(); } =20 @@ -125,6 +133,7 @@ static void leave_ipte_range(void) pte_t *start_cache, *cache; hw_pte_t *ptep, *start; struct ipte_range *range; + unsigned int nr_ptes; int start_idx; =20 if (!static_branch_likely(&lazy_mmu_enabled)) @@ -163,6 +172,9 @@ static void leave_ipte_range(void) range->end_pte =3D NULL; =20 done: + nr_ptes =3D (range->base_end - range->base_addr) / PAGE_SIZE; + kasan_unpoison_pte(range->base_pte, nr_ptes); + range->mm =3D NULL; range->base_addr =3D 0; range->base_end =3D 0; @@ -244,10 +256,17 @@ static void __ipte_range_set_pte(struct ipte_range = *range, hw_pte_t *ptep, pte_t static pte_t __ipte_range_ptep_get(struct ipte_range *range, hw_pte_t *p= tep) { unsigned int idx =3D ptep - range->base_pte; + pte_t pte; =20 lockdep_assert_preemption_disabled(); - if (pte_val(range->cache[idx]) =3D=3D PTE_POISON) - return __ptep_get(ptep); + if (pte_val(range->cache[idx]) =3D=3D PTE_POISON) { + kasan_unpoison_pte(ptep, 1); + pte =3D __ptep_get(ptep); + kasan_poison_pte(ptep, 1); + + return pte; + } + return range->cache[idx]; } =20 --=20 2.53.0