On Mon, 25 Mar 2024 11:12:40 +0000 Steven Price <steven.pr...@arm.com> wrote:
> On 25/03/2024 10:41, Boris Brezillon wrote: > > When mapping an IO region, the pseudo-file offset is dependent on the > > userspace architecture. panthor_device_mmio_offset() abstract 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. > > > > Fixes: 5fe909cae118 ("drm/panthor: Add the device logical block") > > Reported-by: Adrián Larumbe <adrian.laru...@collabora.com> > > Reported-by: Lukas F. Hartmann <lu...@mntmn.com> > > Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10835 > > Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com> > > Pesky 32 bit again ;) > > Looks fine, although I'm wondering whether you'd consider squashing > something like the below on top? I think it helps contain the 32 bit > specific code to the one place. I like that. I'll steal your changes for v2 and update the commit message to reflect the fact we no longer need this panthor_device_mmio_offset() helper. > Either way: > > Reviewed-by: Steven Price <steven.pr...@arm.com> > > --- > diff --git a/drivers/gpu/drm/panthor/panthor_device.c > b/drivers/gpu/drm/panthor/panthor_device.c > index f7f8184b1992..75276cbeba20 100644 > --- a/drivers/gpu/drm/panthor/panthor_device.c > +++ b/drivers/gpu/drm/panthor/panthor_device.c > @@ -392,7 +392,7 @@ 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 offset = panthor_device_mmio_offset((u64)vma->vm_pgoff << > PAGE_SHIFT); > + u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT; > > switch (offset) { > case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET: > @@ -406,9 +406,6 @@ int panthor_device_mmap_io(struct panthor_device *ptdev, > struct vm_area_struct * > return -EINVAL; > } > > - /* Adjust vm_pgoff for 32-bit userspace on 64-bit kernel. */ > - vma->vm_pgoff = offset >> PAGE_SHIFT; > - > /* Defer actual mapping to the fault handler. */ > vma->vm_private_data = ptdev; > vma->vm_ops = &panthor_mmio_vm_ops; > diff --git a/drivers/gpu/drm/panthor/panthor_device.h > b/drivers/gpu/drm/panthor/panthor_device.h > index 8e2922c79aca..99ad576912b3 100644 > --- a/drivers/gpu/drm/panthor/panthor_device.h > +++ b/drivers/gpu/drm/panthor/panthor_device.h > @@ -373,30 +373,6 @@ 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 11b3ccd58f85..730dd0c69cb8 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); >