Re: [PATCH 4/4] drm/tegra: Use u64_to_user_ptr helper

From: Dmitry Osipenko
Date: Fri Aug 18 2017 - 18:05:27 EST


On 18.08.2017 19:15, Mikko Perttunen wrote:
> Use the u64_to_user_ptr helper macro to cast IOCTL argument u64 values
> to user pointers instead of writing out the cast manually.
>
> Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
> ---
> drivers/gpu/drm/tegra/drm.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index e3331a2bc082..78c98736b0a5 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -389,11 +389,10 @@ int tegra_drm_submit(struct tegra_drm_context *context,
> unsigned int num_relocs = args->num_relocs;
> unsigned int num_waitchks = args->num_waitchks;
> struct drm_tegra_cmdbuf __user *cmdbufs =
> - (void __user *)(uintptr_t)args->cmdbufs;
> - struct drm_tegra_reloc __user *relocs =
> - (void __user *)(uintptr_t)args->relocs;
> + u64_to_user_ptr(args->cmdbufs);
> + struct drm_tegra_reloc __user *relocs = u64_to_user_ptr(args->relocs);
> struct drm_tegra_waitchk __user *waitchks =
> - (void __user *)(uintptr_t)args->waitchks;
> + u64_to_user_ptr(args->waitchks);

What about to factor out 'u64_to_user_ptr()' assignments to reduce messiness a
tad? Like this:

struct drm_tegra_waitchk __user *waitchks;
struct drm_tegra_cmdbuf __user *cmdbufs;
struct drm_tegra_reloc __user *relocs;
...
waitchks = u64_to_user_ptr(args->waitchks);
cmdbufs = u64_to_user_ptr(args->cmdbufs);
relocs = u64_to_user_ptr(args->relocs);


> struct drm_tegra_syncpt syncpt;
> struct host1x *host1x = dev_get_drvdata(drm->dev->parent);
> struct host1x_syncpt *sp;
> @@ -520,7 +519,7 @@ int tegra_drm_submit(struct tegra_drm_context *context,
> }
> }
>
> - if (copy_from_user(&syncpt, (void __user *)(uintptr_t)args->syncpts,
> + if (copy_from_user(&syncpt, u64_to_user_ptr(args->syncpts),

What about to define and use 'struct drm_tegra_reloc __user *syncpts' for
consistency with other '__user' definitions?

> sizeof(syncpt))) {
> err = -EFAULT;
> goto fail;
>

--
Dmitry