[PATCH master v3 1/3] ARM: asm: fix miscompilation of 32-bit ENTRY_FUNCTION_WITHSTACK

[Ahmad Fatoum]

gcc-11.1.1 shipped with OSELAS.Toolchain-2021.07.0 hoists a single
instruction from __ARM_SETUP_STACK in front of __barebox_arm_head
breaking the barebox header format for the Raspberry Pi 3. This can't
happen with ARM64 and the Raspberry Pi entry points are currently the
only 32-bit users.

While the resulting barebox image was still bootable, header detection
would fail. Add an intermediate naked function for arm32 to work around
this.

This is not required for plain ENTRY_FUNCTION, because the
board-supplied entry point is already NAKED. For
ENTRY_FUNCTION_WITH_FUNCTION, that naked entry point is moved
to arch code intentionally to reduce pitfalls for board code authors..

Fixes: 880c9803b95a ("ARM: implement ENTRY_FUNCTION_WITHSTACK")
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/arm/include/asm/barebox-arm.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index d915cde294a4..15b3b6c44479 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -190,12 +190,13 @@ static inline unsigned long arm_mem_barebox_image(unsigned long membase,
  * Stack top of 0 means stack is already set up. In that case, the follow-up
  * code block will not be inlined and may spill to stack right away.
  */
+#ifdef CONFIG_CPU_64
 #define ENTRY_FUNCTION_WITHSTACK(name, stack_top, arg0, arg1, arg2)	\
 	void name(ulong r0, ulong r1, ulong r2);			\
 									\
 	static void __##name(ulong, ulong, ulong);			\
 									\
-	void NAKED __section(.text_head_entry_##name)	name		\
+	void __section(.text_head_entry_##name)	name			\
 				(ulong r0, ulong r1, ulong r2)		\
 		{							\
 			__barebox_arm_head();				\
@@ -204,6 +205,17 @@ static inline unsigned long arm_mem_barebox_image(unsigned long membase,
 		}							\
 		static void noinline __##name				\
 			(ulong arg0, ulong arg1, ulong arg2)
+#else
+#define ENTRY_FUNCTION_WITHSTACK(name, stack_top, arg0, arg1, arg2)	\
+	static void ____##name(ulong, ulong, ulong);			\
+	ENTRY_FUNCTION(name, arg0, arg1, arg2)				\
+	{								\
+		__ARM_SETUP_STACK(stack_top);				\
+		____##name(arg0, arg1, arg2);				\
+	}								\
+	static void noinline ____##name					\
+		(ulong arg0, ulong arg1, ulong arg2)
+#endif
 
 
 #define ENTRY_FUNCTION(name, arg0, arg1, arg2)				\
-- 
2.30.2