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

[Sumit Garg <sumit.garg@linaro.org>]

On Thu, 20 Jan 2022 at 19:42, Jens Wiklander <jens.wiklander@linaro.org> wrote:
>
> On Thu, Jan 20, 2022 at 12:51 PM Sumit Garg <sumit.garg@linaro.org> wrote:
> >
> > On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@linaro.org> 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@linaro.org>
> > > ---
> > >  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.
>
> Fair point, I'll fix what's changed here.
>
> >
> > > +
> > > +       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);
>
> I noticed that too. I'd rather keep it as it is for now as changing
> would a bit of a ABI change even if I doubt that anyone is depending
> on this particular errno value.
>

Okay, I am fine with this.

-Sumit

> >
> > > +               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.
>
> Thanks,
> Jens
>
> >
> > -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
> > >