powerpc/64s/radix: prefetch user address in update_mmu_cache

Prefetch the faulting address in update_mmu_cache to give the page table walker perhaps 100 cycles head start as locks are dropped and the interrupt completed. Signed-off-by: Nicholas Piggin <[email protected]> Signed-off-by: Michael Ellerman <[email protected]>
zandrey · Jun 3, 2018 · 68662f8 · 68662f8
1 parent f569bd9
commit 68662f8
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
@@ -509,8 +509,10 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 	 */
 	unsigned long access, trap;
 
-	if (radix_enabled())
+	if (radix_enabled()) {
+		prefetch((void *)address);
 		return;
+	}
 
 	/* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
 	if (!pte_young(*ptep) || address >= TASK_SIZE)

diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c
@@ -152,7 +152,8 @@ pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
 			  pmd_t *pmd)
 {
-	return;
+	if (radix_enabled())
+		prefetch((void *)addr);
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */