[PATCH V2] cpu: imx8_cpu: Avoid revision to corrupt device tree

[Lothar Waßmann]

Hi,

On Thu, 17 Oct 2024 16:12:36 +0800 Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan at nxp.com>
> 
> U-Boot device tree is padded just after U-Boot proper.
> After the whole stuff loaded to DRAM space, the device tree
> area is conflict with BSS region before U-Boot relocation.
> 
> So any write to BSS area before reloc_fdt will corrupt the
> device tree. Without the fix, there is issue that “binman_init
> failed:-2” on i.MX8MP-EVK board.
> 
Placing the 'revision' variable into the 'data' section would achieve
the same goal without any further code change:
static char revision[4] __section(".data");

> Signed-off-by: Peng Fan <peng.fan at nxp.com>
> ---
> 
> V2:
>  move the rev to malloc area in cpu_imx_plat
>  tested on i.MX8MP EVK
> 
>  drivers/cpu/imx8_cpu.c | 35 ++++++++++++++++++++---------------
>  1 file changed, 20 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/cpu/imx8_cpu.c b/drivers/cpu/imx8_cpu.c
> index 6c0a8c0cbe4..b11f8dc0c91 100644
> --- a/drivers/cpu/imx8_cpu.c
> +++ b/drivers/cpu/imx8_cpu.c
> @@ -20,10 +20,11 @@
>  
>  DECLARE_GLOBAL_DATA_PTR;
>  
> +#define IMX_REV_LEN	4
>  struct cpu_imx_plat {
>  	const char *name;
> -	const char *rev;
>  	const char *type;
> +	char rev[IMX_REV_LEN];
>  	u32 cpu_rsrc;
>  	u32 cpurev;
>  	u32 freq_mhz;
> @@ -69,28 +70,32 @@ static const char *get_imx_type_str(u32 imxtype)
>  	}
>  }
>  
> -static const char *get_imx_rev_str(u32 rev)
> +static void get_imx_rev_str(struct cpu_imx_plat *plat, u32 rev)
>  {
> -	static char revision[4];
> -
>  	if (IS_ENABLED(CONFIG_IMX8)) {
> +		char rev;
> +
>  		switch (rev) {
>  		case CHIP_REV_A:
> -			return "A";
> +			rev = 'A';
> +			break;
>  		case CHIP_REV_B:
> -			return "B";
> +			rev = 'B';
> +			break;
>  		case CHIP_REV_C:
> -			return "C";
> +			rev = 'C';
> +			break;
>  		default:
> -			return "?";
> +			rev = '?';
> +			break;
>  		}
> +		plat->rev[0] = rev;
> +		plat->rev[1] = '\0';
>  	} else {
> -		revision[0] = '1' + (((rev & 0xf0) - CHIP_REV_1_0) >> 4);
> -		revision[1] = '.';
> -		revision[2] = '0' + (rev & 0xf);
> -		revision[3] = '\0';
> -
> -		return revision;
> +		plat->rev[0] = '1' + (((rev & 0xf0) - CHIP_REV_1_0) >> 4);
> +		plat->rev[1] = '.';
> +		plat->rev[2] = '0' + (rev & 0xf);
> +		plat->rev[3] = '\0';
>  	}
>  }
>  
> @@ -318,7 +323,7 @@ static int imx_cpu_probe(struct udevice *dev)
>  	set_core_data(dev);
>  	cpurev = get_cpu_rev();
>  	plat->cpurev = cpurev;
> -	plat->rev = get_imx_rev_str(cpurev & 0xFFF);
> +	get_imx_rev_str(plat, cpurev & 0xFFF);
>  	plat->type = get_imx_type_str((cpurev & 0x1FF000) >> 12);
>  	plat->freq_mhz = imx_get_cpu_rate(dev) / 1000000;
>  	plat->mpidr = dev_read_addr(dev);


Lothar Waßmann
-- 
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