On 22/03/2019 15:59, Catalin Marinas wrote:
On Wed, Mar 20, 2019 at 03:51:28PM +0100, Andrey Konovalov wrote:
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.
amdgpu_ttm_tt_get_user_pages() uses provided user pointers for vma
lookups, which can only by done with untagged pointers.
Untag user pointers in this function.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 73e71e61dc99..891b027fa33b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -751,10 +751,11 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages)
* check that we only use anonymous memory to prevent problems
* with writeback
*/
- unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
+ unsigned long userptr = untagged_addr(gtt->userptr);
+ unsigned long end = userptr + ttm->num_pages * PAGE_SIZE;
struct vm_area_struct *vma;
- vma = find_vma(mm, gtt->userptr);
+ vma = find_vma(mm, userptr);
if (!vma || vma->vm_file || vma->vm_end < end) {
up_read(&mm->mmap_sem);
return -EPERM;
I tried to track this down but I failed to see whether user could
provide an tagged pointer here (under the restrictions as per Vincenzo's
ABI document).
->userptr is set by radeon_ttm_tt_set_userptr(), itself called from
radeon_gem_userptr_ioctl(). Any page-aligned value is allowed.
Kevin
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