[PATCH v3 2/6] vdso/datastore: Map pages in terms of the faults pgoff

["Thomas Weißschuh" <thomas.weissschuh@linutronix.de>]

To support mlockall() on the datapages the VMA can have no holes where
inner pages return VM_FAULT_SIGBUS. An upcoming change will avoid these
holes by mapping a zeroed pages into these holes. That logic will be
simpler when the mapping logic is based on vmf->pgoff instead of the
vdso_k_ symbols.

Switch to the equivalent vmf->pgoff logic.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Tested-by: Nam Cao <namcao@linutronix.de>
---
 lib/vdso/datastore.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lib/vdso/datastore.c b/lib/vdso/datastore.c
index 9d66ac2fdb8d..8aabb289a7b5 100644
--- a/lib/vdso/datastore.c
+++ b/lib/vdso/datastore.c
@@ -29,10 +29,11 @@ struct vdso_arch_data *vdso_k_arch_data __refdata =
 	(void *)&vdso_initdata[VDSO_ARCH_PAGES_START * PAGE_SIZE];
 #endif /* CONFIG_ARCH_HAS_VDSO_ARCH_DATA */
 
+static struct page *vdso_data_pages __ro_after_init;
+
 void __init vdso_setup_data_pages(void)
 {
 	unsigned int order = get_order(VDSO_NR_PAGES * PAGE_SIZE);
-	struct page *vdso_data_pages;
 
 	/*
 	 * Allocate the data pages dynamically. SPARC does not support mapping
@@ -67,13 +68,13 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 {
 	struct page *page, *timens_page;
 
+	page = vdso_data_pages + vmf->pgoff;
 	timens_page = find_timens_vvar_page(vma);
 
 	switch (vmf->pgoff) {
 	case VDSO_TIME_PAGE_OFFSET:
 		if (!IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY))
 			return VM_FAULT_SIGBUS;
-		page = virt_to_page(vdso_k_time_data);
 		if (timens_page) {
 			/*
 			 * Fault in VVAR page too, since it will be accessed
@@ -99,17 +100,15 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		 */
 		if (!IS_ENABLED(CONFIG_TIME_NS) || !timens_page)
 			return VM_FAULT_SIGBUS;
-		page = virt_to_page(vdso_k_time_data);
+		page = vdso_data_pages + VDSO_TIME_PAGE_OFFSET;
 		break;
 	case VDSO_RNG_PAGE_OFFSET:
 		if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM))
 			return VM_FAULT_SIGBUS;
-		page = virt_to_page(vdso_k_rng_data);
 		break;
 	case VDSO_ARCH_PAGES_START ... VDSO_ARCH_PAGES_END:
 		if (!IS_ENABLED(CONFIG_ARCH_HAS_VDSO_ARCH_DATA))
 			return VM_FAULT_SIGBUS;
-		page = virt_to_page(vdso_k_arch_data) + vmf->pgoff - VDSO_ARCH_PAGES_START;
 		break;
 	default:
 		return VM_FAULT_SIGBUS;

-- 
2.53.0