[PATCH v2 05/12] powerpc/pseries/ras: FWNMI_VALID off by one

[Mahesh J Salgaonkar]

On 2020-03-25 20:34:03 Wed, Nicholas Piggin wrote:
> This was discovered developing qemu fwnmi sreset support. This
> off-by-one bug means the last 16 bytes of the rtas area can not
> be used for a 16 byte save area.
> 
> It's not a serious bug, and QEMU implementation has to retain a
> workaround for old kernels, but it's good to tighten it.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>  arch/powerpc/platforms/pseries/ras.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index c74d5e740922..9a37bda47468 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -395,10 +395,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
>  /*
>   * Some versions of FWNMI place the buffer inside the 4kB page starting at
>   * 0x7000. Other versions place it inside the rtas buffer. We check both.
> + * Minimum size of the buffer is 16 bytes.

Acked-by: Mahesh Salgaonkar <mahesh at linux.ibm.com>

Thanks,
-Mahesh.

>   */
>  #define VALID_FWNMI_BUFFER(A) \
> -	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
> -	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
> +	((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
> +	(((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))
> 
>  static inline struct rtas_error_log *fwnmi_get_errlog(void)
>  {
> -- 
> 2.23.0
> 

-- 
Mahesh J Salgaonkar