[PATCH master 3/3] ARM64: reloc: fix relocation error for big fat bareboxes

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

A multi_v8 barebox with KASAN enabled is 2051804 even after compression
and this breaks linking for me:

  arch/arm/cpu/common.o: in function `global_variable_offset':
  arch/arm/include/asm/reloc.h:20:(.text.relocate_to_current_adr+0x1c):
    relocation truncated to fit: R_AARCH64_ADR_PREL_LO21 against symbol
    `_text' defined in .text section in .tmp_barebox1
  arch/arm/include/asm/reloc.h:20:(.text.relocate_to_current_adr+0x40):
    relocation truncated to fit: R_AARCH64_ADR_PREL_LO21 against symbol
    `_text' defined in .text section in .tmp_barebox1

This is due to adr's limitation of only addressing bytes +/- 1 MiB from
the current PC. We have a solution for this in the form of the adrp
macro, which we define for out-of-line assembly. Opencode this into the
inline assembly function, by using adrp to compute the page offset and
then add to arrive at the correct offset within the page.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/include/asm/reloc.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/reloc.h b/arch/arm/include/asm/reloc.h
index 95b4ef0af88b..2d7411ab5284 100644
--- a/arch/arm/include/asm/reloc.h
+++ b/arch/arm/include/asm/reloc.h
@@ -18,7 +18,8 @@ static inline __prereloc unsigned long global_variable_offset(void)
 	unsigned long text;
 
 	__asm__ __volatile__(
-		"adr    %0, _text\n"
+		"adrp   %0, _text\n"
+		"add    %0, %0, :lo12:_text\n"
 		: "=r" (text)
 		:
 		: "memory");
-- 
2.39.2