powerpc/mm: Use pte_user() instead of open coding

We have a common declaration in pte-common.h Add a book3s specific one
and switch to pte_user() in callchain.c. In a subsequent patch we will
switch _PAGE_USER to _PAGE_PRIVILEGED in the book3s version only.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -185,6 +185,11 @@ extern struct page *pgd_page(pgd_t pgd);
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val((pte)) & ~_PAGE_PTE })
 #define __swp_entry_to_pte(x)	__pte((x).val | _PAGE_PTE)
 
+static inline bool pte_user(pte_t pte)
+{
+	return !!(pte_val(pte) & _PAGE_USER);
+}
+
 #ifdef CONFIG_MEM_SOFT_DIRTY
 #define _PAGE_SWP_SOFT_DIRTY   (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE))
 #else

arch/powerpc/perf/callchain.c

@@ -137,7 +137,7 @@ static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
 	offset = addr & ((1UL << shift) - 1);
 
 	pte = READ_ONCE(*ptep);
-	if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER))
+	if (!pte_present(pte) || !pte_user(pte))
 		goto err_out;
 	pfn = pte_pfn(pte);
 	if (!page_is_ram(pfn))