1 files changed, 24 insertions, 4 deletions

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 56c3327bbf79..e72f3100958f 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -414,13 +414,24 @@ static int __init arm64_enter_virtual_mode(void)
         for_each_efi_memory_desc(&memmap, md) {
                 if (!(md->attribute & EFI_MEMORY_RUNTIME))
                         continue;
-                if (remap_region(md, &virt_md))
-                        ++count;
+                if (!remap_region(md, &virt_md))
+                        goto err_unmap;
+                ++count;
         }
 
         efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table);
-        if (efi.systab)
-                set_bit(EFI_SYSTEM_TABLES, &efi.flags);
+        if (!efi.systab) {
+                /*
+                 * If we have no virtual mapping for the System Table at this
+                 * point, the memory map doesn't cover the physical offset where
+                 * it resides. This means the System Table will be inaccessible
+                 * to Runtime Services themselves once the virtual mapping is
+                 * installed.
+                 */
+                pr_err("Failed to remap EFI System Table -- buggy firmware?\n");
+                goto err_unmap;
+        }
+        set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 
         local_irq_save(flags);
         cpu_switch_mm(idmap_pg_dir, &init_mm);
@@ -453,5 +464,14 @@ static int __init arm64_enter_virtual_mode(void)
         set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 
         return 0;
+
+err_unmap:
+        /* unmap all mappings that succeeded: there are 'count' of those */
+        for (virt_md = virtmap; count--; virt_md += memmap.desc_size) {
+                md = virt_md;
+                iounmap((__force void __iomem *)md->virt_addr);
+        }
+        kfree(virtmap);
+        return -1;
 }
 early_initcall(arm64_enter_virtual_mode);