[PATCH 4.9 37/78] efi: provide empty efi_enter_virtual_mode implementation

[Greg Kroah-Hartman]

From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

[ Upstream commit 2c547f9da0539ad1f7ef7f08c8c82036d61b011a ]

When CONFIG_EFI is not enabled, we might get an undefined reference to
efi_enter_virtual_mode() error, if this efi_enabled() call isn't inlined
into start_kernel().  This happens in particular, if start_kernel() is
annodated with __no_sanitize_address.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Elena Petrova <lenaptr@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Walter Wu <walter-zh.wu@xxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/6514652d3a32d3ed33d6eb5c91d0af63bf0d1a0c.1596544734.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/linux/efi.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 02c4f16685b69..69605956beb85 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -910,7 +910,11 @@ extern void *efi_get_pal_addr (void);
 extern void efi_map_pal_code (void);
 extern void efi_memmap_walk (efi_freemem_callback_t callback, void *arg);
 extern void efi_gettimeofday (struct timespec64 *ts);
+#ifdef CONFIG_EFI
 extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if possible */
+#else
+static inline void efi_enter_virtual_mode (void) {}
+#endif
 #ifdef CONFIG_X86
 extern void efi_late_init(void);
 extern void efi_free_boot_services(void);
-- 
2.25.1