1 files changed, 13 insertions, 34 deletions

diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c
index df1ffd8b20f2..fa2a1b83b9b0 100644
--- a/arch/powerpc/perf/callchain_64.c
+++ b/arch/powerpc/perf/callchain_64.c
@@ -11,7 +11,6 @@
 #include <linux/uaccess.h>
 #include <linux/mm.h>
 #include <asm/ptrace.h>
-#include <asm/pgtable.h>
 #include <asm/sigcontext.h>
 #include <asm/ucontext.h>
 #include <asm/vdso.h>
@@ -26,43 +25,23 @@
  */
 int read_user_stack_slow(void __user *ptr, void *buf, int nb)
 {
-	int ret = -EFAULT;
-	pgd_t *pgdir;
-	pte_t *ptep, pte;
-	unsigned int shift;
+
 	unsigned long addr = (unsigned long) ptr;
 	unsigned long offset;
-	unsigned long pfn, flags;
+	struct page *page;
 	void *kaddr;
 
-	pgdir = current->mm->pgd;
-	if (!pgdir)
-		return -EFAULT;
+	if (get_user_page_fast_only(addr, FOLL_WRITE, &page)) {
+		kaddr = page_address(page);
+
+		/* align address to page boundary */
+		offset = addr & ~PAGE_MASK;
 
-	local_irq_save(flags);
-	ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
-	if (!ptep)
-		goto err_out;
-	if (!shift)
-		shift = PAGE_SHIFT;
-
-	/* align address to page boundary */
-	offset = addr & ((1UL << shift) - 1);
-
-	pte = READ_ONCE(*ptep);
-	if (!pte_present(pte) || !pte_user(pte))
-		goto err_out;
-	pfn = pte_pfn(pte);
-	if (!page_is_ram(pfn))
-		goto err_out;
-
-	/* no highmem to worry about here */
-	kaddr = pfn_to_kaddr(pfn);
-	memcpy(buf, kaddr + offset, nb);
-	ret = 0;
-err_out:
-	local_irq_restore(flags);
-	return ret;
+		memcpy(buf, kaddr + offset, nb);
+		put_page(page);
+		return 0;
+	}
+	return -EFAULT;
 }
 
 static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
@@ -71,7 +50,7 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
 	    ((unsigned long)ptr & 7))
 		return -EFAULT;
 
-	if (!probe_user_read(ret, ptr, sizeof(*ret)))
+	if (!copy_from_user_nofault(ret, ptr, sizeof(*ret)))
 		return 0;
 
 	return read_user_stack_slow(ptr, ret, 8);