@@ -51,6 +51,13 @@
#define EFI_DEBUG 1
+#define EFI_MIN_RESERVE 5120
+
+#define EFI_DUMMY_GUID \
+ EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
+
+static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
+
struct efi __read_mostly efi = {
.mps = EFI_INVALID_TABLE_ADDR,
.acpi = EFI_INVALID_TABLE_ADDR,
@@ -972,6 +979,13 @@ void __init efi_enter_virtual_mode(void)
runtime_code_page_mkexec();
kfree(new_memmap);
+
+ /* clean DUMMY object */
+ efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+ EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS,
+ 0, NULL);
}
/*
@@ -1023,14 +1037,65 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
efi_status_t status;
u64 storage_size, remaining_size, max_size;
+ if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
+ return 0;
+
status = efi.query_variable_info(attributes, &storage_size,
&remaining_size, &max_size);
if (status != EFI_SUCCESS)
return status;
- if (!storage_size || size > remaining_size || size > max_size ||
- (remaining_size - size) < (storage_size / 2))
- return EFI_OUT_OF_RESOURCES;
+ /*
+ * Some firmware implementations refuse to boot if there's insufficient
+ * space in the variable store. We account for that by refusing the
+ * write if permitting it would reduce the available space to under
+ * 5KB. This figure was provided by Samsung, so should be safe.
+ */
+ if ((remaining_size - size < EFI_MIN_RESERVE) &&
+ !efi_no_storage_paranoia) {
+
+ /*
+ * Triggering garbage collection may require that the firmware
+ * generate a real EFI_OUT_OF_RESOURCES error. We can force
+ * that by attempting to use more space than is available.
+ */
+ unsigned long dummy_size = remaining_size + 1024;
+ void *dummy = kmalloc(dummy_size, GFP_ATOMIC);
+
+ status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+ EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS,
+ dummy_size, dummy);
+
+ if (status == EFI_SUCCESS) {
+ /*
+ * This should have failed, so if it didn't make sure
+ * that we delete it...
+ */
+ efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+ EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS,
+ 0, dummy);
+ }
+
+ /*
+ * The runtime code may now have triggered a garbage collection
+ * run, so check the variable info again
+ */
+ status = efi.query_variable_info(attributes, &storage_size,
+ &remaining_size, &max_size);
+
+ if (status != EFI_SUCCESS)
+ return status;
+
+ /*
+ * There still isn't enough room, so return an error
+ */
+ if (remaining_size - size < EFI_MIN_RESERVE)
+ return EFI_OUT_OF_RESOURCES;
+ }
return EFI_SUCCESS;
}