[PATCH 16/19] mm: Remove follow_pte()

Peter Xu
2024-08-09T16:10:07Z

follow_pte() users have been converted to follow_pfnmap*(). Remove the
API.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
include/linux/mm.h | 2 --
mm/memory.c | 73 ----------------------------------------------
2 files changed, 75 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7471302658af..c5949b8052c6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2369,8 +2369,6 @@ void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
int
copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma);
-int follow_pte(struct vm_area_struct *vma, unsigned long address,
- pte_t **ptepp, spinlock_t **ptlp);
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write);

diff --git a/mm/memory.c b/mm/memory.c
index 313c17eedf56..72f61fffdda2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6265,79 +6265,6 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
}
#endif /* __PAGETABLE_PMD_FOLDED */

-/**
- * follow_pte - look up PTE at a user virtual address
- * @vma: the memory mapping
- * @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 using
- * pte_unmap_unlock(). This function will fail if the PTE is non-present.
- * Present PTEs may include PTEs that map refcounted pages, such as
- * anonymous folios in COW mappings.
- *
- * Callers must be careful when relying on PTE content after
- * pte_unmap_unlock(). Especially if the PTE maps a refcounted page,
- * callers must protect against invalidation with MMU notifiers; otherwise
- * access to the PFN at a later point in time can trigger use-after-free.
- *
- * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
- * should be taken for read.
- *
- * This function must not be used to modify PTE content.
- *
- * Return: zero on success, -ve otherwise.
- */
-int follow_pte(struct vm_area_struct *vma, unsigned long address,
- pte_t **ptepp, spinlock_t **ptlp)
-{
- struct mm_struct *mm = vma->vm_mm;
- pgd_t *pgd;
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep;
-
- mmap_assert_locked(mm);
- if (unlikely(address < vma->vm_start || address >= vma->vm_end))
- goto out;
-
- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- goto out;
-
- pgd = pgd_offset(mm, address);
- if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
- goto out;
-
- p4d = p4d_offset(pgd, address);
- if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
- goto out;
-
- pud = pud_offset(p4d, address);
- if (pud_none(*pud) || unlikely(pud_bad(*pud)))
- goto out;
-
- pmd = pmd_offset(pud, address);
- VM_BUG_ON(pmd_trans_huge(*pmd));
-
- ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
- if (!ptep)
- goto out;
- if (!pte_present(ptep_get(ptep)))
- goto unlock;
- *ptepp = ptep;
- return 0;
-unlock:
- pte_unmap_unlock(ptep, *ptlp);
-out:
- return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(follow_pte);
-
static inline void pfnmap_args_setup(struct follow_pfnmap_args *args,
spinlock_t *lock, pte_t *ptep,
pgprot_t pgprot, unsigned long pfn_base,
--
2.45.0