[PATCH 15/19] mm/access_process_vm: Use the new follow_pfnmap API

[Peter Xu <peterx@redhat.com>]

Use the new API that can understand huge pfn mappings.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/memory.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 2194e0f9f541..313c17eedf56 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6504,34 +6504,34 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 	resource_size_t phys_addr;
 	unsigned long prot = 0;
 	void __iomem *maddr;
-	pte_t *ptep, pte;
-	spinlock_t *ptl;
 	int offset = offset_in_page(addr);
 	int ret = -EINVAL;
+	bool writable;
+	struct follow_pfnmap_args args = { .vma = vma, .address = addr };
 
 retry:
-	if (follow_pte(vma, addr, &ptep, &ptl))
+	if (follow_pfnmap_start(&args))
 		return -EINVAL;
-	pte = ptep_get(ptep);
-	pte_unmap_unlock(ptep, ptl);
+	prot = pgprot_val(args.pgprot);
+	phys_addr = (resource_size_t)args.pfn << PAGE_SHIFT;
+	writable = args.writable;
+	follow_pfnmap_end(&args);
 
-	prot = pgprot_val(pte_pgprot(pte));
-	phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
-
-	if ((write & FOLL_WRITE) && !pte_write(pte))
+	if ((write & FOLL_WRITE) && !writable)
 		return -EINVAL;
 
 	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
 	if (!maddr)
 		return -ENOMEM;
 
-	if (follow_pte(vma, addr, &ptep, &ptl))
+	if (follow_pfnmap_start(&args))
 		goto out_unmap;
 
-	if (!pte_same(pte, ptep_get(ptep))) {
-		pte_unmap_unlock(ptep, ptl);
+	if ((prot != pgprot_val(args.pgprot)) ||
+	    (phys_addr != (args.pfn << PAGE_SHIFT)) ||
+	    (writable != args.writable)) {
+		follow_pfnmap_end(&args);
 		iounmap(maddr);
-
 		goto retry;
 	}
 
@@ -6540,7 +6540,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 	else
 		memcpy_fromio(buf, maddr + offset, len);
 	ret = len;
-	pte_unmap_unlock(ptep, ptl);
+	follow_pfnmap_end(&args);
 out_unmap:
 	iounmap(maddr);
 
-- 
2.45.0