Re: [PATCH v2 03/12] tee: add tee_shm_alloc_user_buf()

From: Sumit Garg
Date: Tue Jan 18 2022 - 08:11:39 EST


On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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
>