Re: [PATCH 13/14] powerpc/rtas: enture rtas_call is called with MMU enabled

[Laurent Dufour <ldufour@linux.ibm.com>]

On 08/03/2022, 14:50:46, Nicholas Piggin wrote:
> rtas_call must not be called with the MMU disabled because in case
> of rtas error, log_error is called which requires MMU enabled. Add
> a test and warning for this.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>

> ---
>  arch/powerpc/kernel/rtas.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 1fc22138e3ab..adf4892aeecd 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -479,6 +479,11 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
>  	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
>  		return -1;
>  
> +	if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
> +		WARN_ON_ONCE(1);
> +		return -1;
> +	}
> +
>  	s = lock_rtas();
>  
>  	/* We use the global rtas args buffer */