diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 41 |
1 files changed, 36 insertions, 5 deletions
diff --git a/mm/memory.c b/mm/memory.c index feff48e1465a..985dac0958dc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4709,9 +4709,9 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) } #endif /* __PAGETABLE_PMD_FOLDED */ -int follow_pte(struct mm_struct *mm, unsigned long address, - struct mmu_notifier_range *range, pte_t **ptepp, pmd_t **pmdpp, - spinlock_t **ptlp) +int follow_invalidate_pte(struct mm_struct *mm, unsigned long address, + struct mmu_notifier_range *range, pte_t **ptepp, + pmd_t **pmdpp, spinlock_t **ptlp) { pgd_t *pgd; p4d_t *p4d; @@ -4777,6 +4777,34 @@ out: } /** + * follow_pte - look up PTE at a user virtual address + * @mm: the mm_struct of the target address space + * @address: user virtual address + * @ptepp: location to store found PTE + * @ptlp: location to store the lock for the PTE + * + * On a successful return, the pointer to the PTE is stored in @ptepp; + * the corresponding lock is taken and its location is stored in @ptlp. + * The contents of the PTE are only stable until @ptlp is released; + * any further use, if any, must be protected against invalidation + * with MMU notifiers. + * + * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore + * should be taken for read. + * + * KVM uses this function. While it is arguably less bad than ``follow_pfn``, + * it is not a good general-purpose API. + * + * Return: zero on success, -ve otherwise. + */ +int follow_pte(struct mm_struct *mm, unsigned long address, + pte_t **ptepp, spinlock_t **ptlp) +{ + return follow_invalidate_pte(mm, address, NULL, ptepp, NULL, ptlp); +} +EXPORT_SYMBOL_GPL(follow_pte); + +/** * follow_pfn - look up PFN at a user virtual address * @vma: memory mapping * @address: user virtual address @@ -4784,6 +4812,9 @@ out: * * Only IO mappings and raw PFN mappings are allowed. * + * This function does not allow the caller to read the permissions + * of the PTE. Do not use it. + * * Return: zero and the pfn at @pfn on success, -ve otherwise. */ int follow_pfn(struct vm_area_struct *vma, unsigned long address, @@ -4796,7 +4827,7 @@ int follow_pfn(struct vm_area_struct *vma, unsigned long address, if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) return ret; - ret = follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl); + ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); if (ret) return ret; *pfn = pte_pfn(*ptep); @@ -4817,7 +4848,7 @@ int follow_phys(struct vm_area_struct *vma, if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) goto out; - if (follow_pte(vma->vm_mm, address, NULL, &ptep, NULL, &ptl)) + if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) goto out; pte = *ptep; |