Re: [PATCH v2 04/10] arm: socfpga: iossm: store size in bytes

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

Hello,

On 4/9/26 3:52 PM, Michael Tretter wrote:
> The mem_width_info is the memory size in gigabits. Convert it to bytes
> before storing it for each bank to have a more convenient format and
> simplify the conversion when reading the value.
> 
> Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
> ---
> Changes in v2:
> 
> - Change memory_size in io96b_mb_ctrl to phys_size_t to prevent overflow

Thanks for addressing the concern. I looked it over and there's still a
chance for overflow.

> diff --git a/arch/arm/mach-socfpga/iossm_mailbox.c b/arch/arm/mach-socfpga/iossm_mailbox.c
> index 9299fee71e0b..042ea4a99e5c 100644
> --- a/arch/arm/mach-socfpga/iossm_mailbox.c
> +++ b/arch/arm/mach-socfpga/iossm_mailbox.c
> @@ -9,6 +9,7 @@
>  #include <common.h>
>  #include <io.h>
>  #include <linux/bitfield.h>
> +#include <linux/sizes.h>
>  #include "iossm_mailbox.h"
>  #include <mach/socfpga/generic.h>
>  #include <mach/socfpga/soc64-regs.h>
> @@ -404,21 +405,25 @@ int io96b_get_mem_width_info(struct io96b_info *io96b_ctrl)
>  	struct io96b_mb_resp usr_resp;
>  	struct io96b_mb_ctrl *mb_ctrl;
>  	int i, j;
> -	u16 memory_size;
> -	u16 total_memory_size = 0;
> +	phys_size_t memory_size;
> +	u32 mem_width_info;
> +	phys_size_t total_memory_size = 0;
>  
>  	/* Get all memory interface(s) total memory size on all instance(s) */
>  	for (i = 0; i < io96b_ctrl->num_instance; i++) {
>  		mb_ctrl = &io96b_ctrl->io96b[i].mb_ctrl;
>  		memory_size = 0;
> +
>  		for (j = 0; j < mb_ctrl->num_mem_interface; j++) {
>  			io96b_mb_req_no_param(io96b_ctrl->io96b[i].io96b_csr_addr,
>  					      mb_ctrl->ip_type[j],
>  					      mb_ctrl->ip_instance_id[j],
>  					      CMD_GET_MEM_INFO, GET_MEM_WIDTH_INFO, &usr_resp);
> +			mem_width_info = usr_resp.cmd_resp_data[1] & GENMASK(7, 0);

I assume this is the RAM memory width in bytes, e.g. 2 or 4 bytes, but
the mask  allows it to be up to 255.

>  
> -			memory_size = memory_size +
> -				(usr_resp.cmd_resp_data[1] & GENMASK(7, 0));
> +			mb_ctrl->memory_size[j] = mem_width_info * (SZ_1G / SZ_8);

SZ_4G / (SZ_1G / 8) = 32

So the maximum value permitted in mem_width_info without overflowing is
31, but the code accepts up to 255. As all types on the left hand side
are 32-bit only.

Worth a check or adaptation of the mask?

Cheers,
Ahmad

> +
> +			memory_size += mb_ctrl->memory_size[j];
>  		}
>  
>  		if (!memory_size) {
> diff --git a/arch/arm/mach-socfpga/iossm_mailbox.h b/arch/arm/mach-socfpga/iossm_mailbox.h
> index bd66621d5f70..0c15c92bb867 100644
> --- a/arch/arm/mach-socfpga/iossm_mailbox.h
> +++ b/arch/arm/mach-socfpga/iossm_mailbox.h
> @@ -79,6 +79,7 @@ struct io96b_mb_ctrl {
>  	u32 num_mem_interface;
>  	u32 ip_type[2];
>  	u32 ip_instance_id[2];
> +	phys_size_t memory_size[2];
>  };
>  
>  /*
> @@ -101,7 +102,7 @@ struct io96b_mb_resp {
>   * @mb_ctrl:		IOSSM mailbox required information
>   */
>  struct io96b_instance {
> -	u16 size;
> +	phys_size_t size;
>  	phys_addr_t io96b_csr_addr;
>  	bool cal_status;
>  	struct io96b_mb_ctrl mb_ctrl;
> @@ -126,7 +127,7 @@ struct io96b_info {
>  	bool			 overall_cal_status;
>  	const char		*ddr_type;
>  	bool			 ecc_status;
> -	u16			 overall_size;
> +	phys_size_t		 overall_size;
>  	struct io96b_instance	 io96b[MAX_IO96B_SUPPORTED];
>  	bool			 ckgen_lock;
>  	u8			 num_port;
> 

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