On Tue, Mar 26, 2024 at 12:12:03PM +0100, Boris Brezillon wrote:
> When mapping an IO region, the pseudo-file offset is dependent on the
> userspace architecture. panthor_device_mmio_offset() abstracts that
> away for us by turning a userspace MMIO offset into its kernel
> equivalent, but we were not updating vm_area_struct::vm_pgoff
> accordingly, leading us to attach the MMIO region to the wrong file
> offset.
>
> This has implications when we start mixing 64 bit and 32 bit apps, but
> that's only really a problem when we start having more that 2^43 bytes of
> memory allocated, which is very unlikely to happen.
>
> What's more problematic is the fact this turns our
> unmap_mapping_range(DRM_PANTHOR_USER_MMIO_OFFSET) calls, which are
> supposed to kill the MMIO mapping when entering suspend, into NOPs.
> Which means we either keep the dummy flush_id mapping active at all
> times, or we risk a BUS_FAULT if the MMIO region was mapped, and the
> GPU is suspended after that.
>
> Solve that by patching vm_pgoff early in panthor_mmap(). With
> this in place, we no longer need the panthor_device_mmio_offset()
> helper.
>
> v3:
> - No changes
>
> v2:
> - Kill panthor_device_mmio_offset()
>
> Fixes: 5fe909cae118 ("drm/panthor: Add the device logical block")
> Reported-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> Reported-by: Lukas F. Hartmann <lukas@xxxxxxxxx>
> Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10835
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Reviewed-by: Steven Price <steven.price@xxxxxxx>
Reviewed-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Best regards,
Liviu
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 8 ++++----
> drivers/gpu/drm/panthor/panthor_device.h | 24 ------------------------
> drivers/gpu/drm/panthor/panthor_drv.c | 17 ++++++++++++++++-
> 3 files changed, 20 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index bfe8da4a6e4c..3ddc4ba0acbe 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -334,7 +334,7 @@ static vm_fault_t panthor_mmio_vm_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct panthor_device *ptdev = vma->vm_private_data;
> - u64 id = (u64)vma->vm_pgoff << PAGE_SHIFT;
> + u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT;
> unsigned long pfn;
> pgprot_t pgprot;
> vm_fault_t ret;
> @@ -347,7 +347,7 @@ static vm_fault_t panthor_mmio_vm_fault(struct vm_fault *vmf)
> mutex_lock(&ptdev->pm.mmio_lock);
> active = atomic_read(&ptdev->pm.state) == PANTHOR_DEVICE_PM_STATE_ACTIVE;
>
> - switch (panthor_device_mmio_offset(id)) {
> + switch (offset) {
> case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET:
> if (active)
> pfn = __phys_to_pfn(ptdev->phys_addr + CSF_GPU_LATEST_FLUSH_ID);
> @@ -378,9 +378,9 @@ static const struct vm_operations_struct panthor_mmio_vm_ops = {
>
> int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *vma)
> {
> - u64 id = (u64)vma->vm_pgoff << PAGE_SHIFT;
> + u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT;
>
> - switch (panthor_device_mmio_offset(id)) {
> + switch (offset) {
> case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET:
> if (vma->vm_end - vma->vm_start != PAGE_SIZE ||
> (vma->vm_flags & (VM_WRITE | VM_EXEC)))
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index 51c9d61b6796..7ee4987a3796 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -365,30 +365,6 @@ static int panthor_request_ ## __name ## _irq(struct panthor_device *ptdev, \
> pirq); \
> }
>
> -/**
> - * panthor_device_mmio_offset() - Turn a user MMIO offset into a kernel one
> - * @offset: Offset to convert.
> - *
> - * With 32-bit systems being limited by the 32-bit representation of mmap2's
> - * pgoffset field, we need to make the MMIO offset arch specific. This function
> - * converts a user MMIO offset into something the kernel driver understands.
> - *
> - * If the kernel and userspace architecture match, the offset is unchanged. If
> - * the kernel is 64-bit and userspace is 32-bit, the offset is adjusted to match
> - * 64-bit offsets. 32-bit kernel with 64-bit userspace is impossible.
> - *
> - * Return: Adjusted offset.
> - */
> -static inline u64 panthor_device_mmio_offset(u64 offset)
> -{
> -#ifdef CONFIG_ARM64
> - if (test_tsk_thread_flag(current, TIF_32BIT))
> - offset += DRM_PANTHOR_USER_MMIO_OFFSET_64BIT - DRM_PANTHOR_USER_MMIO_OFFSET_32BIT;
> -#endif
> -
> - return offset;
> -}
> -
> extern struct workqueue_struct *panthor_cleanup_wq;
>
> #endif
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index ff484506229f..0097a01d0fc7 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -1327,7 +1327,22 @@ static int panthor_mmap(struct file *filp, struct vm_area_struct *vma)
> if (!drm_dev_enter(file->minor->dev, &cookie))
> return -ENODEV;
>
> - if (panthor_device_mmio_offset(offset) >= DRM_PANTHOR_USER_MMIO_OFFSET)
> +#ifdef CONFIG_ARM64
> + /*
> + * With 32-bit systems being limited by the 32-bit representation of
> + * mmap2's pgoffset field, we need to make the MMIO offset arch
> + * specific. This converts a user MMIO offset into something the kernel
> + * driver understands.
> + */
> + if (test_tsk_thread_flag(current, TIF_32BIT) &&
> + offset >= DRM_PANTHOR_USER_MMIO_OFFSET_32BIT) {
> + offset += DRM_PANTHOR_USER_MMIO_OFFSET_64BIT -
> + DRM_PANTHOR_USER_MMIO_OFFSET_32BIT;
> + vma->vm_pgoff = offset >> PAGE_SHIFT;
> + }
> +#endif
> +
> + if (offset >= DRM_PANTHOR_USER_MMIO_OFFSET)
> ret = panthor_device_mmap_io(ptdev, vma);
> else
> ret = drm_gem_mmap(filp, vma);
> --
> 2.44.0
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
