Re: [PATCH v2 11/12] tee: replace tee_shm_register()

From: Sumit Garg
Date: Thu Jan 20 2022 - 06:51:28 EST

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On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> tee_shm_register() is replaced by the previously introduced functions
> tee_shm_register_user_buf() and tee_shm_register_kernel_buf().
>
> Since there are not external callers left we can remove tee_shm_register()
> and refactor the remains.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> ---
> drivers/tee/tee_shm.c | 157 +++++++++++++++++++++++-----------------
> include/linux/tee_drv.h | 11 ---
> 2 files changed, 91 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 6a1dbce75616..fe3e5977dd7c 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -12,17 +12,43 @@
> #include <linux/uio.h>
> #include "tee_private.h"
>
> +static void shm_put_kernel_pages(struct page **pages, unsigned long npages)
> +{
> + unsigned long n;

nit: Can we have a consistent prototype for the number of pages?
size_t as used by struct tee_shm or unsigned long? Same holds true for
variables below as well: npages, page_count, num_pages, n.

> +
> + for (n = 0; n < npages; n++)
> + put_page(pages[n]);
> +}
> +
> +static int shm_get_kernel_pages(unsigned long start, int page_count,
> + struct page **pages)
> +{
> + struct kvec *kiov;
> + unsigned int n;
> + int rc;
> +
> + kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> + if (!kiov)
> + return -ENOMEM;
> +
> + for (n = 0; n < page_count; n++) {
> + kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> + kiov[n].iov_len = PAGE_SIZE;
> + }
> +
> + rc = get_kernel_pages(kiov, page_count, 0, pages);
> + kfree(kiov);
> +
> + return rc;
> +}
> +
> static void release_registered_pages(struct tee_shm *shm)
> {
> if (shm->pages) {
> - if (shm->flags & TEE_SHM_USER_MAPPED) {
> + if (shm->flags & TEE_SHM_USER_MAPPED)
> unpin_user_pages(shm->pages, shm->num_pages);
> - } else {
> - size_t n;
> -
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> - }
> + else
> + shm_put_kernel_pages(shm->pages, shm->num_pages);
>
> kfree(shm->pages);
> }
> @@ -191,28 +217,24 @@ struct tee_shm *tee_shm_alloc_priv_kernel_buf(struct tee_context *ctx,
> }
> EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_kernel_buf);
>
> -struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> - size_t length, u32 flags)
> +static struct tee_shm *
> +register_shm_helper(struct tee_context *ctx, unsigned long addr,
> + size_t length, u32 flags, int id)
> {
> struct tee_device *teedev = ctx->teedev;
> - const u32 req_user_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
> - const u32 req_kernel_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
> struct tee_shm *shm;
> + unsigned long start;
> + int num_pages;
> void *ret;
> int rc;
> - int num_pages;
> - unsigned long start;
> -
> - if (flags != req_user_flags && flags != req_kernel_flags)
> - return ERR_PTR(-ENOTSUPP);
>
> if (!tee_device_get(teedev))
> return ERR_PTR(-EINVAL);
>
> if (!teedev->desc->ops->shm_register ||
> !teedev->desc->ops->shm_unregister) {
> - tee_device_put(teedev);
> - return ERR_PTR(-ENOTSUPP);
> + ret = ERR_PTR(-ENOTSUPP);

Checkpatch warns about this error code:

WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP
#104: FILE: drivers/tee/tee_shm.c:236:
+ ret = ERR_PTR(-ENOTSUPP);

> + goto err_dev_put;
> }
>
> teedev_ctx_get(ctx);
> @@ -220,13 +242,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> shm = kzalloc(sizeof(*shm), GFP_KERNEL);
> if (!shm) {
> ret = ERR_PTR(-ENOMEM);
> - goto err;
> + goto err_ctx_put;
> }
>
> refcount_set(&shm->refcount, 1);
> - shm->flags = flags | TEE_SHM_REGISTER;
> + shm->flags = flags;
> shm->ctx = ctx;
> - shm->id = -1;
> + shm->id = id;
> addr = untagged_addr(addr);
> start = rounddown(addr, PAGE_SIZE);
> shm->offset = addr - start;
> @@ -235,71 +257,45 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
> if (!shm->pages) {
> ret = ERR_PTR(-ENOMEM);
> - goto err;
> + goto err_free_shm;
> }
>
> - if (flags & TEE_SHM_USER_MAPPED) {
> + if (flags & TEE_SHM_USER_MAPPED)
> rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
> shm->pages);
> - } else {
> - struct kvec *kiov;
> - int i;
> -
> - kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
> - if (!kiov) {
> - ret = ERR_PTR(-ENOMEM);
> - goto err;
> - }
> -
> - for (i = 0; i < num_pages; i++) {
> - kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
> - kiov[i].iov_len = PAGE_SIZE;
> - }
> -
> - rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
> - kfree(kiov);
> - }
> + else
> + rc = shm_get_kernel_pages(start, num_pages, shm->pages);
> if (rc > 0)
> shm->num_pages = rc;
> if (rc != num_pages) {
> if (rc >= 0)
> rc = -ENOMEM;
> ret = ERR_PTR(rc);
> - goto err;
> - }
> -
> - mutex_lock(&teedev->mutex);
> - shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
> - mutex_unlock(&teedev->mutex);
> -
> - if (shm->id < 0) {
> - ret = ERR_PTR(shm->id);
> - goto err;
> + goto err_put_shm_pages;
> }
>
> rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
> shm->num_pages, start);
> if (rc) {
> ret = ERR_PTR(rc);
> - goto err;
> + goto err_put_shm_pages;
> }
>
> return shm;
> -err:
> - if (shm) {
> - if (shm->id >= 0) {
> - mutex_lock(&teedev->mutex);
> - idr_remove(&teedev->idr, shm->id);
> - mutex_unlock(&teedev->mutex);
> - }
> - release_registered_pages(shm);
> - }
> +err_put_shm_pages:
> + if (flags & TEE_SHM_USER_MAPPED)
> + unpin_user_pages(shm->pages, shm->num_pages);
> + else
> + shm_put_kernel_pages(shm->pages, shm->num_pages);
> + kfree(shm->pages);
> +err_free_shm:
> kfree(shm);
> +err_ctx_put:
> teedev_ctx_put(ctx);
> +err_dev_put:
> tee_device_put(teedev);
> return ret;
> }
> -EXPORT_SYMBOL_GPL(tee_shm_register);
>
> /**
> * tee_shm_register_user_buf() - Register a userspace shared memory buffer
> @@ -312,8 +308,36 @@ EXPORT_SYMBOL_GPL(tee_shm_register);
> 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);
> + u32 f = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED | TEE_SHM_REGISTER;

nit: I would prefer to write variable name as "flags" for clarity.

> + struct tee_device *teedev = ctx->teedev;
> + struct tee_shm *shm;
> + void *ret;
> + int id;
> +
> + mutex_lock(&teedev->mutex);
> + id = idr_alloc(&teedev->idr, NULL, 1, 0, GFP_KERNEL);
> + mutex_unlock(&teedev->mutex);
> +

nit: redundant extra line.

> + if (id < 0)
> + return ERR_PTR(id);
> +
> + shm = register_shm_helper(ctx, addr, length, f, id);
> + if (IS_ERR(shm)) {
> + mutex_lock(&teedev->mutex);
> + idr_remove(&teedev->idr, id);
> + mutex_unlock(&teedev->mutex);
> + return shm;
> + }
> +
> + mutex_lock(&teedev->mutex);
> + ret = idr_replace(&teedev->idr, shm, id);
> + mutex_unlock(&teedev->mutex);
> + if (IS_ERR(ret)) {
> + tee_shm_free(shm);
> + return ret;
> + }
> +
> + return shm;
> }
> EXPORT_SYMBOL_GPL(tee_shm_register_user_buf);
>
> @@ -330,8 +354,9 @@ EXPORT_SYMBOL_GPL(tee_shm_register_user_buf);
> 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);
> + u32 f = TEE_SHM_REGISTER | TEE_SHM_KERNEL_MAPPED;

Ditto.

-Sumit

> +
> + return register_shm_helper(ctx, (unsigned long)addr, length, f, -1);
> }
> EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);
>
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index 029c9a0590cc..e4f32885e273 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -278,17 +278,6 @@ struct tee_shm *tee_shm_alloc_priv_kernel_buf(struct tee_context *ctx,
> size_t size);
> struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
>
> -/**
> - * tee_shm_register() - Register shared memory buffer
> - * @ctx: Context that registers the shared memory
> - * @addr: Address is userspace of the shared buffer
> - * @length: Length of the shared buffer
> - * @flags: Flags setting properties for the requested shared memory.
> - *
> - * @returns a pointer to 'struct tee_shm'
> - */
> -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,
> --
> 2.31.1
>

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