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c=simple/simple; d=arm.com; s=foss; t=1788245703; bh=azovFHyuoM3M1QIKlu9UrG4EHV9CqavEpXrZmiNGkU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D8VzCyXQSX+7dZrHhOE9ruOuTTvVRHuCsBZT4IBYETdjEN5AUxk4hf97bBbfq44i6 c81fpEHWqkkoFgJebUuaxtqbXrlleRNOMTq1hHOKQny5lC8f4bZ212nNNJxmQ3vxR1 eNDWhuP0YWkeTVNMjzpIn/zyLe0t0bw6nrxVxvcg= From: Anshuman Khandual To: linux-arm-kernel@lists.infradead.org Cc: Anshuman Khandual , David Hildenbrand , Mike Rapoport , Andrew Morton , Lorenzo Stoakes , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 1/2] arm64/mm: Move __check_safe_pte_update() Date: Tue, 1 Sep 2026 12:24:53 +0530 Message-ID: <20260901065454.1906343-2-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260901065454.1906343-1-anshuman.khandual@arm.com> References: <20260901065454.1906343-1-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: di5puu5nuonezxurfa68jmxcqd4sf9kq X-Rspamd-Queue-Id: 5ED4C20007 X-Rspamd-Server: rspam06 X-HE-Tag: 1788245704-404638 X-HE-Meta: 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 vRyUws8m aSNkiSzFMsBslJ9PWzjssaEMdfwYE86zLuat5OOOy7kNtH7K92/W7LXCDNaQQlZv4828KfhUHvSSuGCGgiYaE0TsLtDuqceFV7GEqki0qPGMOv2jfC8w5H7jlSE/y+gqAvlYLQfP/PJjto5cTvzjrWTsm+ERMd0HGWGcBDtU3oaPMAcEnBpZkJ0UofEhgPUimTSsgyzBfVRrKg6uFizxltw666kVkuYCszUA9LbSCnH6PYeeRPMJwavaFl/MGw9xdGtIoNs5R0tOTXpZ1YxhJvgYaR4d2LbRRItefGilZNVdjZ9Zd+AZaYtdHTRZfl2Moi6N1McGOvB7tkKrxvM7usRe6FWmUOuqGkOk86todD2yEBVSYBa3wFaOW7eGb11tAM4zUAXMZjK6H2Mw+YE8gV2e//pd6arAzi90/14N9RYK02qs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The page table entry print helpers and related macros which are defined in will not be accessible in platform which is basically caused by cycling dependency. Move __check_safe_pte_update() inside arch/arm64/mm/mmu.c as a preparation for subsequent usage of the afore mentioned generic MM helpers. This does not cause any functional change. Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual --- Should __check_safe_pte_update() be wrapped in #ifdef CONFIG_DEBUG_VM along with dropping off current IS_ENABLED() test. That would ensure the function never gets called when CONFIG_DEBUG_VM is disabled. That will preserve current behaviour as the inline function gets dropped when CONFIG_DEBUG_VM remains disabled. arch/arm64/include/asm/pgtable.h | 47 +------------------------------- arch/arm64/mm/mmu.c | 45 ++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+), 46 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e89ec5f4787b..61fbfab3e06e 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -387,52 +387,7 @@ static inline pte_t __ptep_get(pte_t *ptep) extern void __sync_icache_dcache(pte_t pteval); bool pgattr_change_is_safe(pteval_t old, pteval_t new); -/* - * PTE bits configuration in the presence of hardware Dirty Bit Management - * (PTE_WRITE == PTE_DBM): - * - * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw) - * 0 0 | 1 0 0 - * 0 1 | 1 1 0 - * 1 0 | 1 0 1 - * 1 1 | 0 1 x - * - * When hardware DBM is not present, the software PTE_DIRTY bit is updated via - * the page fault mechanism. Checking the dirty status of a pte becomes: - * - * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) - */ - -static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, - pte_t pte) -{ - pte_t old_pte; - - if (!IS_ENABLED(CONFIG_DEBUG_VM)) - return; - - old_pte = __ptep_get(ptep); - - if (!pte_valid(old_pte) || !pte_valid(pte)) - return; - if (mm != current->active_mm && atomic_read(&mm->mm_users) <= 1) - return; - - /* - * Check for potential race with hardware updates of the pte - * (__ptep_set_access_flags safely changes valid ptes without going - * through an invalid entry). - */ - VM_WARN_ONCE(!pte_young(pte), - "%s: racy access flag clearing: 0x%016llx -> 0x%016llx", - __func__, pte_val(old_pte), pte_val(pte)); - VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), - "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx", - __func__, pte_val(old_pte), pte_val(pte)); - VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)), - "%s: unsafe attribute change: 0x%016llx -> 0x%016llx", - __func__, pte_val(old_pte), pte_val(pte)); -} +void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte); static inline void __sync_cache_and_tags(pte_t pte, unsigned int nr_pages) { diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 79d90226fd5d..e9c66d26bc0a 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -2392,4 +2392,49 @@ int arch_set_user_pkey_access(int pkey, unsigned long init_val) return 0; } + +/* + * PTE bits configuration in the presence of hardware Dirty Bit Management + * (PTE_WRITE == PTE_DBM): + * + * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw) + * 0 0 | 1 0 0 + * 0 1 | 1 1 0 + * 1 0 | 1 0 1 + * 1 1 | 0 1 x + * + * When hardware DBM is not present, the software PTE_DIRTY bit is updated via + * the page fault mechanism. Checking the dirty status of a pte becomes: + * + * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) + */ +void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte) +{ + pte_t old_pte; + + if (!IS_ENABLED(CONFIG_DEBUG_VM)) + return; + + old_pte = __ptep_get(ptep); + + if (!pte_valid(old_pte) || !pte_valid(pte)) + return; + if (mm != current->active_mm && atomic_read(&mm->mm_users) <= 1) + return; + + /* + * Check for potential race with hardware updates of the pte + * (__ptep_set_access_flags safely changes valid ptes without going + * through an invalid entry). + */ + VM_WARN_ONCE(!pte_young(pte), + "%s: racy access flag clearing: 0x%016llx -> 0x%016llx", + __func__, pte_val(old_pte), pte_val(pte)); + VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte), + "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx", + __func__, pte_val(old_pte), pte_val(pte)); + VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)), + "%s: unsafe attribute change: 0x%016llx -> 0x%016llx", + __func__, pte_val(old_pte), pte_val(pte)); +} #endif -- 2.43.0