linux-kernel - Re: [PATCH v2 03/12] tee: add tee_shm_alloc_user

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Date:   Tue, 18 Jan 2022 18:41:20 +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 03/12] tee: add tee_shm_alloc_user_buf()

On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@...aro.org> wrote:
>
> Adds a new function tee_shm_alloc_user_buf() or user mode allocations,
> replacing passing the flags TEE_SHM_MAPPED | TEE_SHM_DMA_BUF to
> tee_shm_alloc().
>
> Signed-off-by: Jens Wiklander <jens.wiklander@...aro.org>
> ---
>  drivers/tee/tee_core.c     |  2 +-
>  drivers/tee/tee_shm.c      | 18 ++++++++++++++++++
>  drivers/tee/tee_shm_pool.c |  2 +-
>  include/linux/tee_drv.h    |  3 ++-
>  4 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index 3fc426dad2df..a15812baaeb1 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -297,7 +297,7 @@ static int tee_ioctl_shm_alloc(struct tee_context *ctx,
>         if (data.flags)
>                 return -EINVAL;
>
> -       shm = tee_shm_alloc(ctx, data.size, TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
> +       shm = tee_shm_alloc_user_buf(ctx, data.size);

Since it's the only place this API would be used within the driver
itself and I can't see any future usage from other kernel drivers..

>         if (IS_ERR(shm))
>                 return PTR_ERR(shm);
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 499fccba3d74..b43178986985 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -127,6 +127,24 @@ struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
>  }
>  EXPORT_SYMBOL_GPL(tee_shm_alloc);
>
> +/**
> + * tee_shm_alloc_user_buf() - Allocate shared memory for user space
> + * @ctx:       Context that allocates the shared memory
> + * @size:      Requested size of shared memory
> + *
> + * Memory allocated as user space shared memory is automatically freed when
> + * the TEE file pointer is closed. The primary usage of this function is
> + * when the TEE driver doesn't support registering ordinary user space
> + * memory.
> + *
> + * @returns a pointer to 'struct tee_shm'
> + */
> +struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size)
> +{
> +       return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED | TEE_SHM_DMA_BUF);
> +}
> +EXPORT_SYMBOL_GPL(tee_shm_alloc_user_buf);
> +

..so I don't see any value-add for this export..

>  /**
>   * tee_shm_alloc_kernel_buf() - Allocate shared memory for kernel buffer
>   * @ctx:       Context that allocates the shared memory
> diff --git a/drivers/tee/tee_shm_pool.c b/drivers/tee/tee_shm_pool.c
> index a9f9d50fd181..0e460347138a 100644
> --- a/drivers/tee/tee_shm_pool.c
> +++ b/drivers/tee/tee_shm_pool.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /*
> - * Copyright (c) 2015, Linaro Limited
> + * Copyright (c) 2015, 2017, 2022 Linaro Limited
>   */
>  #include <linux/device.h>
>  #include <linux/dma-buf.h>
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index 6b0f0d01ebdf..26b450484ac1 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -1,6 +1,6 @@
>  /* SPDX-License-Identifier: GPL-2.0-only */
>  /*
> - * Copyright (c) 2015-2016, Linaro Limited
> + * Copyright (c) 2015-2022 Linaro Limited
>   */
>
>  #ifndef __TEE_DRV_H
> @@ -308,6 +308,7 @@ void *tee_get_drvdata(struct tee_device *teedev);
>   * @returns a pointer to 'struct tee_shm'
>   */
>  struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags);
> +struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size);

..and it should rather belong to drivers/tee/tee_private.h.

-Sumit

>  struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
>
>  /**
> --
> 2.31.1
>