Mailing List Archive: [PATCH] arm: optee: don't print warning about "wrong" RPC buffer

On Mon, 5 Oct 2020, Volodymyr Babchuk wrote:
> OP-TEE mediator tracks cookie value for a last buffer which
> was requested by OP-TEE. This tracked value serves one important
> purpose: if OP-TEE wants to request another buffer, we know
> that it finished importing previous one and we can free page list
> associated with it.
>
> Also, we had false premise that OP_TEE will free requested buffers in
> reversed order. So we checked rpc_data_cookie during handling
> OPTEE_RPC_CMD_SHM_FREE call and printed warning if cookie of buffer
> which is requested to be freed differs from last allocated one.
>
> During testing RPMB FS services I discovered, that RPMB code frees
> request and response buffers in the same order is it allocated
> them. And this is perfectly fine, actually.
>
> So, we are removing mentioned warning message in Xen, as it is
> perfectly normal to free buffers in arbitrary order.
>
> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

I am going to fix the grammar on commit

> ---
> xen/arch/arm/tee/optee.c | 20 +-------------------
> 1 file changed, 1 insertion(+), 19 deletions(-)
>
> diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
> index 8a39fe33b0..ee85359742 100644
> --- a/xen/arch/arm/tee/optee.c
> +++ b/xen/arch/arm/tee/optee.c
> @@ -1127,25 +1127,7 @@ static int handle_rpc_return(struct optee_domain *ctx,
> */
> if ( shm_rpc->xen_arg->cmd == OPTEE_RPC_CMD_SHM_FREE )
> {
> - uint64_t cookie = shm_rpc->xen_arg->params[0].u.value.b;
> -
> - free_optee_shm_buf(ctx, cookie);
> -
> - /*
> - * OP-TEE asks to free the buffer, but this is not the same
> - * buffer we previously allocated for it. While nothing
> - * prevents OP-TEE from asking this, it is the strange
> - * situation. This may or may not be caused by a bug in
> - * OP-TEE or mediator. But is better to print warning.
> - */
> - if ( call->rpc_data_cookie && call->rpc_data_cookie != cookie )
> - {
> - gprintk(XENLOG_ERR,
> - "Saved RPC cookie does not corresponds to OP-TEE's (%"PRIx64" != %"PRIx64")\n",
> - call->rpc_data_cookie, cookie);
> -
> - WARN();
> - }
> + free_optee_shm_buf(ctx, shm_rpc->xen_arg->params[0].u.value.b);
> call->rpc_data_cookie = 0;
> }
> unmap_domain_page(shm_rpc->xen_arg);
> --
> 2.27.0
>