[PATCH v2 3/3] mm: move follow_phys to arch/x86/mm/pat/memtype.c

[David Hildenbrand]

From: Christoph Hellwig <hch@xxxxxx>

follow_phys is only used by two callers in arch/x86/mm/pat/memtype.c.
Move it there and hardcode the two arguments that get the same values
passed by both callers.

Link: https://lkml.kernel.org/r/20240324234542.2038726-4-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fei Li <fei1.li@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> # rebased, applied fixups
---
 arch/x86/mm/pat/memtype.c | 29 ++++++++++++++++++++++++++++-
 include/linux/mm.h        |  2 --
 mm/memory.c               | 32 --------------------------------
 3 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index 36b603d0cdde..d01c3b0bd6eb 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -39,6 +39,7 @@
 #include <linux/pfn_t.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
+#include <linux/highmem.h>
 #include <linux/fs.h>
 #include <linux/rbtree.h>
 
@@ -947,6 +948,32 @@ static void free_pfn_range(u64 paddr, unsigned long size)
 		memtype_free(paddr, paddr + size);
 }
 
+static int follow_phys(struct vm_area_struct *vma, unsigned long *prot,
+		resource_size_t *phys)
+{
+	pte_t *ptep, pte;
+	spinlock_t *ptl;
+
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+		return -EINVAL;
+
+	if (follow_pte(vma->vm_mm, vma->vm_start, &ptep, &ptl))
+		return -EINVAL;
+
+	pte = ptep_get(ptep);
+
+	/* Never return PFNs of anon folios in COW mappings. */
+	if (vm_normal_folio(vma, vma->vm_start, pte)) {
+		pte_unmap_unlock(ptep, ptl);
+		return -EINVAL;
+	}
+
+	*prot = pgprot_val(pte_pgprot(pte));
+	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+	pte_unmap_unlock(ptep, ptl);
+	return 0;
+}
+
 static int get_pat_info(struct vm_area_struct *vma, resource_size_t *paddr,
 		pgprot_t *pgprot)
 {
@@ -964,7 +991,7 @@ static int get_pat_info(struct vm_area_struct *vma, resource_size_t *paddr,
 	 * detect the PFN. If we need the cachemode as well, we're out of luck
 	 * for now and have to fail fork().
 	 */
-	if (!follow_phys(vma, vma->vm_start, 0, &prot, paddr)) {
+	if (!follow_phys(vma, &prot, paddr)) {
 		if (pgprot)
 			*pgprot = __pgprot(prot);
 		return 0;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 97e779993c74..bc0cd34a8042 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2424,8 +2424,6 @@ int
 copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma);
 int follow_pte(struct mm_struct *mm, unsigned long address,
 	       pte_t **ptepp, spinlock_t **ptlp);
-int follow_phys(struct vm_area_struct *vma, unsigned long address,
-		unsigned int flags, unsigned long *prot, resource_size_t *phys);
 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 1e9a0288fdaf..912cd738ec03 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5987,38 +5987,6 @@ int follow_pte(struct mm_struct *mm, unsigned long address,
 EXPORT_SYMBOL_GPL(follow_pte);
 
 #ifdef CONFIG_HAVE_IOREMAP_PROT
-int follow_phys(struct vm_area_struct *vma,
-		unsigned long address, unsigned int flags,
-		unsigned long *prot, resource_size_t *phys)
-{
-	int ret = -EINVAL;
-	pte_t *ptep, pte;
-	spinlock_t *ptl;
-
-	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
-		goto out;
-
-	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
-		goto out;
-	pte = ptep_get(ptep);
-
-	/* Never return PFNs of anon folios in COW mappings. */
-	if (vm_normal_folio(vma, address, pte))
-		goto unlock;
-
-	if ((flags & FOLL_WRITE) && !pte_write(pte))
-		goto unlock;
-
-	*prot = pgprot_val(pte_pgprot(pte));
-	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
-
-	ret = 0;
-unlock:
-	pte_unmap_unlock(ptep, ptl);
-out:
-	return ret;
-}
-
 /**
  * generic_access_phys - generic implementation for iomem mmap access
  * @vma: the vma to access
-- 
2.44.0