1 files changed, 46 insertions, 0 deletions
diff --git a/arch/s390/kernel/abs_lowcore.c b/arch/s390/kernel/abs_lowcore.c
new file mode 100644
index 000000000..f9efc54ec
--- /dev/null
+++ b/arch/s390/kernel/abs_lowcore.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pgtable.h>
+#include <asm/abs_lowcore.h>
+
+unsigned long __bootdata_preserved(__abs_lowcore);
+
+int abs_lowcore_map(int cpu, struct lowcore *lc, bool alloc)
+{
+	unsigned long addr = __abs_lowcore + (cpu * sizeof(struct lowcore));
+	unsigned long phys = __pa(lc);
+	int rc, i;
+
+	for (i = 0; i < LC_PAGES; i++) {
+		rc = __vmem_map_4k_page(addr, phys, PAGE_KERNEL, alloc);
+		if (rc) {
+			/*
+			 * Do not unmap allocated page tables in case the
+			 * allocation was not requested. In such a case the
+			 * request is expected coming from an atomic context,
+			 * while the unmap attempt might sleep.
+			 */
+			if (alloc) {
+				for (--i; i >= 0; i--) {
+					addr -= PAGE_SIZE;
+					vmem_unmap_4k_page(addr);
+				}
+			}
+			return rc;
+		}
+		addr += PAGE_SIZE;
+		phys += PAGE_SIZE;
+	}
+	return 0;
+}
+
+void abs_lowcore_unmap(int cpu)
+{
+	unsigned long addr = __abs_lowcore + (cpu * sizeof(struct lowcore));
+	int i;
+
+	for (i = 0; i < LC_PAGES; i++) {
+		vmem_unmap_4k_page(addr);
+		addr += PAGE_SIZE;
+	}
+}