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Re: [Qemu-arm] [Qemu-devel] [PATCH v4] char: cadence: check baud rate ge


From: Alistair Francis
Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH v4] char: cadence: check baud rate generator and divider values
Date: Fri, 28 Oct 2016 08:34:05 -0700

On Thu, Oct 27, 2016 at 12:24 PM, P J P <address@hidden> wrote:
> From: Prasad J Pandit <address@hidden>
>
> The Cadence UART device emulator calculates speed by dividing the
> baud rate by a 'baud rate generator' & 'baud rate divider' value.
> The device specification defines these register values to be
> non-zero and within certain limits. Add checks for these limits
> to avoid errors like divide by zero.
>
> Reported-by: Huawei PSIRT <address@hidden>
> Signed-off-by: Prasad J Pandit <address@hidden>

This looks good to me. I'll spin up a new patch for the migration fix
next week (I won't have time today).

Reviewed-by: Alistair Francis <address@hidden>

Thanks,

Alistair

> ---
>  hw/char/cadence_uart.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> Update: remove default reset value assignment.
>   -> https://lists.gnu.org/archive/html/qemu-devel/2016-10/msg07206.html
>
> diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
> index e3bc52f..4a3c4c6 100644
> --- a/hw/char/cadence_uart.c
> +++ b/hw/char/cadence_uart.c
> @@ -1,6 +1,11 @@
>  /*
>   * Device model for Cadence UART
>   *
> + * Reference: Xilinx Zynq 7000 reference manual
> + *   - 
> http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf
> + *   - Chapter 19 UART Controller
> + *   - Appendix B for Register details
> + *
>   * Copyright (c) 2010 Xilinx Inc.
>   * Copyright (c) 2012 Peter A.G. Crosthwaite (address@hidden)
>   * Copyright (c) 2012 PetaLogix Pty Ltd.
> @@ -410,6 +415,16 @@ static void uart_write(void *opaque, hwaddr offset,
>              break;
>          }
>          break;
> +    case R_BRGR: /* Baud rate generator */
> +        if (value >= 0x01) {
> +            s->r[offset] = value & 0xFFFF;
> +        }
> +        break;
> +    case R_BDIV:    /* Baud rate divider */
> +        if (value >= 0x04) {
> +            s->r[offset] = value & 0xFF;
> +        }
> +        break;
>      default:
>          s->r[offset] = value;
>      }
> --
> 2.7.4
>
>



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