linux-kernel - Re: [PATCH v2 09/12] tee: add tee_shm_register_{user,kernel}

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Date:   Thu, 20 Jan 2022 16:30:28 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Jens Wiklander <jens.wiklander@...aro.org>
Cc:     linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Devaraj Rangasamy <Devaraj.Rangasamy@....com>,
        Rijo Thomas <Rijo-john.Thomas@....com>,
        David Howells <dhowells@...hat.com>,
        Tyler Hicks <tyhicks@...ux.microsoft.com>
Subject: Re: [PATCH v2 09/12] tee: add tee_shm_register_{user,kernel}_buf()

On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@...aro.org> wrote:
>
> Adds the two new functions tee_shm_register_user_buf() and
> tee_shm_register_kernel_buf() which should be used instead of the old
> tee_shm_register().
>
> This avoids having the caller supplying the flags parameter which
> exposes a bit more than desired of the internals of the TEE subsystem.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@...aro.org>
> ---
>  drivers/tee/tee_core.c  |  3 +--
>  drivers/tee/tee_shm.c   | 34 ++++++++++++++++++++++++++++++++++
>  include/linux/tee_drv.h |  4 ++++
>  3 files changed, 39 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index a15812baaeb1..8aa1a4836b92 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -334,8 +334,7 @@ tee_ioctl_shm_register(struct tee_context *ctx,
>         if (data.flags)
>                 return -EINVAL;
>
> -       shm = tee_shm_register(ctx, data.addr, data.length,
> -                              TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED);
> +       shm = tee_shm_register_user_buf(ctx, data.addr, data.length);
>         if (IS_ERR(shm))
>                 return PTR_ERR(shm);
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index d51bf97ce7e5..6a1dbce75616 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -301,6 +301,40 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>  }
>  EXPORT_SYMBOL_GPL(tee_shm_register);
>
> +/**
> + * tee_shm_register_user_buf() - Register a userspace shared memory buffer
> + * @ctx:       Context that registers the shared memory
> + * @addr:      The userspace address of the shared buffer
> + * @length:    Length of the shared buffer
> + *
> + * @returns a pointer to 'struct tee_shm'
> + */
> +struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
> +                                         unsigned long addr, size_t length)
> +{
> +       return tee_shm_register(ctx, addr, length,
> +                               TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED);
> +}
> +EXPORT_SYMBOL_GPL(tee_shm_register_user_buf);
> +

Similar comment as for tee_shm_alloc_user_buf() in patch #3. This
isn't required to be exported but rather a private function to TEE
core.

-Sumit

> +/**
> + * tee_shm_register_kernel_buf() - Register kernel memory to be shared with
> + *                                secure world
> + * @ctx:       Context that registers the shared memory
> + * @addr:      The buffer
> + * @length:    Length of the buffer
> + *
> + * @returns a pointer to 'struct tee_shm'
> + */
> +
> +struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
> +                                           void *addr, size_t length)
> +{
> +       return tee_shm_register(ctx, (unsigned long)addr, length,
> +                               TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED);
> +}
> +EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);
> +
>  static int tee_shm_fop_release(struct inode *inode, struct file *filp)
>  {
>         tee_shm_put(filp->private_data);
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index e71cb0411e9c..029c9a0590cc 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -289,6 +289,10 @@ struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
>   */
>  struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>                                  size_t length, u32 flags);
> +struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
> +                                         unsigned long addr, size_t length);
> +struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
> +                                           void *addr, size_t length);
>
>  /**
>   * tee_shm_is_registered() - Check if shared memory object in registered in TEE
> --
> 2.31.1
>