[PATCH v2 1/3] [mm-unstable] Revert "mm: move follow_phys to arch/x86/mm/pat/memtype.c"

[David Hildenbrand <david@xxxxxxxxxx>]

Revert mm-unstable patches:
 * mm-move-follow_phys-to-arch-x86-mm-pat-memtypec-fix-2
 * mm-move-follow_phys-to-arch-x86-mm-pat-memtypec-fix
 * mm: move follow_phys to arch/x86/mm/pat/memtype.c

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 arch/x86/mm/pat/memtype.c | 24 ++----------------------
 include/linux/mm.h        |  2 ++
 mm/memory.c               | 28 ++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index 143d1e3d3fd2..0d72183b5dd0 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -39,7 +39,6 @@
 #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>
 
@@ -948,25 +947,6 @@ 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);
-	*prot = pgprot_val(pte_pgprot(pte));
-	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
-	pte_unmap_unlock(ptep, ptl);
-	return 0;
-}
-
 /*
  * track_pfn_copy is called when vma that is covering the pfnmap gets
  * copied through copy_page_range().
@@ -986,7 +966,7 @@ int track_pfn_copy(struct vm_area_struct *vma)
 		 * reserve the whole chunk covered by vma. We need the
 		 * starting address and protection from pte.
 		 */
-		if (follow_phys(vma, &prot, &paddr)) {
+		if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) {
 			WARN_ON_ONCE(1);
 			return -EINVAL;
 		}
@@ -1073,7 +1053,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
 	/* free the chunk starting from pfn or the whole chunk */
 	paddr = (resource_size_t)pfn << PAGE_SHIFT;
 	if (!paddr && !size) {
-		if (follow_phys(vma, &prot, &paddr)) {
+		if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) {
 			WARN_ON_ONCE(1);
 			return;
 		}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc0cd34a8042..97e779993c74 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2424,6 +2424,8 @@ 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 912cd738ec03..1211e2090c1a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5987,6 +5987,34 @@ 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);
+
+	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