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

[Tom Rini]

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On 07/05/2012 11:10 PM, Tetsuyuki Kobayashi wrote:
> 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 /* 
> *************************************************************************

We
>
> 
shouldn't, I believe, need to call this save_boot_params_default
and then alias it.  We should be able to just call it save_boot_params
and declare it weak, then omap3 for example will override a link time
(this should be easily verifiable with objdump).  Thanks!

- -- 
Tom

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