[U-Boot] [PATCH v4] arm: bugfix: save_boot_params_default accesses uninitalized stack when -O0

[Tetsuyuki Kobayashi]

save_boot_params_default() in cpu.c accesses uninitialized stack area
when it compiled with -O0 (not optimized).

Signed-off-by: Tetsuyuki Kobayashi <koba at kmckk.co.jp>
---
Hi Tom, Albert,

I rewrite them in asm language and put it to start.S.
No warning now.
I tested it quickly on my kzm9g board.

Changes for v2:
 - include <linux/compiler.h> and use __naked instead of __attribute__((naked))

Changes for v3:
 - move __naked after void
 - reformat comments

Changes for v4:
 - v3 causes following warnings
  cpu.c: In function 'save_boot_params_default':
  cpu.c:48:1: warning: -fstack-usage not supported for this target [enabled by default]
 - move save_boot_params_default() and save_boot_params() from cpu.c to start.S
   and write them in asm language

 arch/arm/cpu/armv7/cpu.c   |    7 -------
 arch/arm/cpu/armv7/start.S |   15 +++++++++++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/arm/cpu/armv7/cpu.c b/arch/arm/cpu/armv7/cpu.c
index c6fa8ef..b0677f4 100644
--- a/arch/arm/cpu/armv7/cpu.c
+++ b/arch/arm/cpu/armv7/cpu.c
@@ -37,13 +37,6 @@
 #include <asm/cache.h>
 #include <asm/armv7.h>
 
-void save_boot_params_default(u32 r0, u32 r1, u32 r2, u32 r3)
-{
-}
-
-void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
-	__attribute__((weak, alias("save_boot_params_default")));
-
 int cleanup_before_linux(void)
 {
 	/*
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 261835b..4feade5 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -350,6 +350,21 @@ ENTRY(cpu_init_crit)
 ENDPROC(cpu_init_crit)
 #endif
 
+/*************************************************************************
+ *
+ * void save_boot_params_default(u32 r0, u32 r1, u32 r2, u32 r3)	
+ *
+ * Stack pointer is not yet initialized
+ * Don't save anything to stack even if compiled with -O0
+ *	
+ *************************************************************************/
+ENTRY(save_boot_params_default)
+	bx	lr			@ back to my caller
+ENDPROC(save_boot_params_default)
+
+	.weak	save_boot_params
+	.set	save_boot_params, save_boot_params_default
+
 #ifndef CONFIG_SPL_BUILD
 /*
  *************************************************************************
--
1.7.9.5