[PATCH 1/2 v2] efi: add a function to convert the status value to string

[Lee, Chun-Yi]

This function can be used to convert EFI status value to string
for printing out debug message. Using this function can improve
the readability of log.

v2.
- Changed the wording in subject and description.
- Moved the marco immediately after the status value definitions.
- Turned into a proper function instead of inline.

Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Cc: Kees Cook <keescook at chromium.org>
Cc: Anton Vorontsov <anton at enomsg.org>
Cc: Colin Cross <ccross at android.com>
Cc: Tony Luck <tony.luck at intel.com>
Signed-off-by: "Lee, Chun-Yi" <jlee at suse.com>
---
 include/linux/efi.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 54357a258b35..6f3f89a32eef 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -42,6 +42,34 @@
 #define EFI_ABORTED		(21 | (1UL << (BITS_PER_LONG-1)))
 #define EFI_SECURITY_VIOLATION	(26 | (1UL << (BITS_PER_LONG-1)))
 
+#define EFI_STATUS_STR(_status) \
+case EFI_##_status: \
+	return "EFI_" __stringify(_status);
+
+static __attribute__((unused)) char *
+efi_status_to_str(unsigned long status)
+{
+	switch (status) {
+	EFI_STATUS_STR(SUCCESS)
+	EFI_STATUS_STR(LOAD_ERROR)
+	EFI_STATUS_STR(INVALID_PARAMETER)
+	EFI_STATUS_STR(UNSUPPORTED)
+	EFI_STATUS_STR(BAD_BUFFER_SIZE)
+	EFI_STATUS_STR(BUFFER_TOO_SMALL)
+	EFI_STATUS_STR(NOT_READY)
+	EFI_STATUS_STR(DEVICE_ERROR)
+	EFI_STATUS_STR(WRITE_PROTECTED)
+	EFI_STATUS_STR(OUT_OF_RESOURCES)
+	EFI_STATUS_STR(NOT_FOUND)
+	EFI_STATUS_STR(ABORTED)
+	EFI_STATUS_STR(SECURITY_VIOLATION)
+	default:
+		pr_warn("Unknown efi status: 0x%lx", status);
+	}
+
+	return "Unknown efi status";
+}
+
 typedef unsigned long efi_status_t;
 typedef u8 efi_bool_t;
 typedef u16 efi_char16_t;		/* UNICODE character */
-- 
2.16.4