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Tue, 16 Jun 2026 12:40:39 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with SMTP; Tue, 16 Jun 2026 12:40:39 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 55669) id 8E863E0E21; Tue, 16 Jun 2026 14:40:39 +0200 (CEST) From: Alexander Gordeev To: Gerald Schaefer , Heiko Carstens , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda Cc: linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kevin Brodsky , David Hildenbrand Subject: [PATCH v3 6/7] mm/kasan: Introduce helpers for lazy MMU mode sanitizer Date: Tue, 16 Jun 2026 14:40:38 +0200 Message-ID: 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-Spam-Info: AW1haW4tMjYwNjE2MDEyNSBTYWx0ZWRfX2M9hgxPj5oJb 0F3NsExc8Va46IiKTMXLRysZQVwfB946uEdbxk7KoGgKaOherCE7owiYD9+mpLqo4UdW9eT6obH cHvEtFynvJG7YKy+WrXYgbvMjSfIOF0= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjE2MDEyNSBTYWx0ZWRfX6BqdBTWJ8EHc RD37L6sQWHF74bGTgDNIIJ50kUu5gNkv8TIjHH+iQHjmObk+WrCB0ifKq4+2sVewzoxZnnmUQP4 u+IaYsiGEg3KEAiWNQ0xMZzvWcnSiEapfChp3zYrzCr3PRVOLQkW0JZEkMhc/el3kU/9+5h8/C0 fj2k0KLN1HXv9iQ3PViMyijJscAGcNHaaHLDaclLXBR+nMKxfAb4dCKUpfsovBx68yh0Maf4a6Z O+EwJlx4HJeGerAD7EABnVJ2RROsGpjxW1EF7MA17MCSRLWZQvPC58bh6r2zNzyzTQ/9PgXSUcW aQhOM0jufNAY1d3Oz44N901Fboeo7fd8Ah67nmEF0ObIGQ9XFJsFOGON8MUoO05Cu3g6U7Q9nUr gY1Ob25UJ2d6ILqWtAJEgyEi9WfVn3eFQm6Gvv7Ov8Sk3aHQqChbh9MPLOhtxiOXZnk42pAWn21 nNkrjp3VjQTNohkeP1A== X-Proofpoint-GUID: 4Xqwqj3nFd1R4rD5liTXXmuEnhty_zX4 X-Authority-Analysis: v=2.4 cv=NuDhtcdJ c=1 sm=1 tr=0 ts=6a31444c cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=lldn-txhwCp5ury-Zd0A:9 X-Proofpoint-ORIG-GUID: 4Xqwqj3nFd1R4rD5liTXXmuEnhty_zX4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-16_03,2026-06-15_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 suspectscore=0 impostorscore=0 clxscore=1015 phishscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606040000 definitions=main-2606160125 Provide helpers that allow architectures implement illegitimate PTE direct accesses while the lazy MMU mode is enabled, such as: pte_t pte =3D *ptep; *ptep =3D pte; By contrast, these would have to be: pte_t pte =3D ptep_get(ptep); set_pte(ptep, pte); The direct PTE accesses pose a real issue on s390. Suggested-by: Ilya Leoshkevich Signed-off-by: Alexander Gordeev --- include/linux/kasan.h | 16 ++++++++++++++++ mm/kasan/common.c | 10 ++++++++++ mm/kasan/kasan.h | 2 ++ 3 files changed, 28 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index bf233bde68c7..deadf566b84a 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -134,6 +134,20 @@ static __always_inline void kasan_poison_slab(struct= slab *slab) __kasan_poison_slab(slab); } =20 +void __kasan_poison_pte(pte_t *pte, int nr); +static __always_inline void kasan_poison_pte(pte_t *pte, int nr) +{ + if (kasan_enabled()) + __kasan_poison_pte(pte, nr); +} + +void __kasan_unpoison_pte(pte_t *pte, int nr); +static __always_inline void kasan_unpoison_pte(pte_t *pte, int nr) +{ + if (kasan_enabled()) + __kasan_unpoison_pte(pte, nr); +} + void __kasan_unpoison_new_object(struct kmem_cache *cache, void *object)= ; /** * kasan_unpoison_new_object - Temporarily unpoison a new slab object. @@ -414,6 +428,8 @@ static inline bool kasan_unpoison_pages(struct page *= page, unsigned int order, return false; } static inline void kasan_poison_slab(struct slab *slab) {} +static inline void kasan_poison_pte(pte_t *pte, int nr) {} +static inline void kasan_unpoison_pte(pte_t *pte, int nr) {} static inline void kasan_unpoison_new_object(struct kmem_cache *cache, void *object) {} static inline void kasan_poison_new_object(struct kmem_cache *cache, diff --git a/mm/kasan/common.c b/mm/kasan/common.c index b7d05c2a6d93..cbf68680614e 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -163,6 +163,16 @@ void __kasan_poison_slab(struct slab *slab) KASAN_SLAB_REDZONE, false); } =20 +void __kasan_poison_pte(pte_t *pte, int nr) +{ + kasan_poison(pte, sizeof(*pte) * nr, KASAN_LAZY_MMU_PTE, false); +} + +void __kasan_unpoison_pte(pte_t *pte, int nr) +{ + kasan_unpoison(pte, sizeof(*pte) * nr, false); +} + void __kasan_unpoison_new_object(struct kmem_cache *cache, void *object) { kasan_unpoison(object, cache->object_size, false); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index fc9169a54766..8ba0fbabd75b 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -144,12 +144,14 @@ static inline bool kasan_requires_meta(void) #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocation= */ #define KASAN_SLAB_REDZONE 0xFC /* redzone for slab object */ #define KASAN_SLAB_FREE 0xFB /* freed slab object */ +#define KASAN_LAZY_MMU_PTE 0xFD #define KASAN_VMALLOC_INVALID 0xF8 /* inaccessible space in vmap area *= / #else #define KASAN_PAGE_FREE KASAN_TAG_INVALID #define KASAN_PAGE_REDZONE KASAN_TAG_INVALID #define KASAN_SLAB_REDZONE KASAN_TAG_INVALID #define KASAN_SLAB_FREE KASAN_TAG_INVALID +#define KASAN_LAZY_MMU_PTE KASAN_TAG_INVALID #define KASAN_VMALLOC_INVALID KASAN_TAG_INVALID /* only used for SW_TAGS= */ #endif =20 --=20 2.53.0