mm/vmalloc: add vmap_range_noflush variant

ascend inclusion
category: feature
bugzilla: NA
CVE: NA

https://lwn.net/ml/linux-kernel/20200825145753.529284-11-npiggin@gmail.com/
--------------

As a side-effect, the order of flush_cache_vmap() and
arch_sync_kernel_mappings() calls are switched, but that now matches
the other callers in this file.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NRui Xiang <rui.xiang@huawei.com>
Reviewed-by: NDing Tianhong <dingtianhong@huawei.com>
Reviewed-by: NZefan Li <lizefan@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

mm/vmalloc.c

@@ -209,7 +209,7 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 	return 0;
 }
 
-int vmap_range(unsigned long addr, unsigned long end,
+static int vmap_range_noflush(unsigned long addr, unsigned long end,
 			phys_addr_t phys_addr, pgprot_t prot,
 			unsigned int max_page_shift)
 {
@@ -230,7 +230,17 @@ int vmap_range(unsigned long addr, unsigned long end,
 			break;
 	} while (pgd++, phys_addr += (next - addr), addr = next, addr != end);
 
-	flush_cache_vmap(start, end);
+	return err;
+}
+
+int vmap_range(unsigned long addr, unsigned long end,
+			phys_addr_t phys_addr, pgprot_t prot,
+			unsigned int max_page_shift)
+{
+	int err;
+
+	err = vmap_range_noflush(addr, end, phys_addr, prot, max_page_shift);
+	flush_cache_vmap(addr, end);
 
 	return err;
 }