drm/radeon: fixup locking inversion between, mmap_sem and reservations

op 08-10-13 18:58, Thomas Hellstrom schreef:
> On 10/08/2013 06:47 PM, Jerome Glisse wrote:
>> On Tue, Oct 08, 2013 at 06:29:35PM +0200, Thomas Hellstrom wrote:
>>> On 10/08/2013 04:55 PM, Jerome Glisse wrote:
>>>> On Tue, Oct 08, 2013 at 04:45:18PM +0200, Christian König wrote:
>>>>> Am 08.10.2013 16:33, schrieb Jerome Glisse:
>>>>>> On Tue, Oct 08, 2013 at 04:14:40PM +0200, Maarten Lankhorst wrote:
>>>>>>> Allocate and copy all kernel memory before doing reservations. This prevents a locking
>>>>>>> inversion between mmap_sem and reservation_class, and allows us to drop the trylocking
>>>>>>> in ttm_bo_vm_fault without upsetting lockdep.
>>>>>>>
>>>>>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
>>>>>> I would say NAK. Current code only allocate temporary page in AGP case.
>>>>>> So AGP case is userspace -> temp page -> cs checker -> radeon ib.
>>>>>>
>>>>>> Non AGP is directly memcpy to radeon IB.
>>>>>>
>>>>>> Your patch allocate memory memcpy userspace to it and it will then be
>>>>>> memcpy to IB. Which means you introduce an extra memcpy in the process
>>>>>> not something we want.
>>>>> Totally agree. Additional to that there is no good reason to provide
>>>>> anything else than anonymous system memory to the CS ioctl, so the
>>>>> dependency between the mmap_sem and reservations are not really
>>>>> clear to me.
>>>>>
>>>>> Christian.
>>>> I think is that in other code path you take mmap_sem first then reserve
>>>> bo. But here we reserve bo and then we take mmap_sem because of copy
>>> >from user.
>>>> Cheers,
>>>> Jerome
>>>>
>>> Actually the log message is a little confusing. I think the mmap_sem
>>> locking inversion problem is orthogonal to what's being fixed here.
>>>
>>> This patch fixes the possible recursive bo::reserve caused by
>>> malicious user-space handing a pointer to ttm memory so that the ttm
>>> fault handler is called when bos are already reserved. That may
>>> cause a (possibly interruptible) livelock.
>>>
>>> Once that is fixed, we are free to choose the mmap_sem ->
>>> bo::reserve locking order. Currently it's bo::reserve->mmap_sem(),
>>> but the hack required in the ttm fault handler is admittedly a bit
>>> ugly.  The plan is to change the locking order to
>>> mmap_sem->bo::reserve
>>>
>>> I'm not sure if it applies to this particular case, but it should be
>>> possible to make sure that copy_from_user_inatomic() will always
>>> succeed, by making sure the pages are present using
>>> get_user_pages(), and release the pages after
>>> copy_from_user_inatomic() is done. That way there's no need for a
>>> double memcpy slowpath, but if the copied data is very fragmented I
>>> guess the resulting code may look ugly. The get_user_pages()
>>> function will return an error if it hits TTM pages.
>>>
>>> /Thomas
>> get_user_pages + copy_from_user_inatomic is overkill. We should just
>> do get_user_pages which fails with ttm memory and then use copy_highpage
>> helper.
>>
>> Cheers,
>> Jerome
> Yeah, it may well be that that's the preferred solution.
>
> /Thomas
>
I still disagree, and shuffled radeon_ib_get around to be called sooner.

How does the patch below look?
8<-------
Allocate and copy all kernel memory before doing reservations. This prevents a locking
inversion between mmap_sem and reservation_class, and allows us to drop the trylocking
in ttm_bo_vm_fault without upsetting lockdep.

Changes since v1:
- Kill extra memcpy for !AGP case.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 92 insertions, 206 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
index 66c222836631..c8ab019a980e 100644
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -213,9 +213,7 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data)
                         return -EFAULT;
                 }
                 p->chunks[i].length_dw = user_chunk.length_dw;
-                p->chunks[i].kdata = NULL;
                 p->chunks[i].chunk_id = user_chunk.chunk_id;
-                p->chunks[i].user_ptr = (void __user *)(unsigned long)user_chunk.chunk_data;
                 if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_RELOCS) {
                         p->chunk_relocs_idx = i;
                 }
@@ -238,25 +236,31 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data)
                                 return -EINVAL;
                 }
 
-                cdata = (uint32_t *)(unsigned long)user_chunk.chunk_data;
-                if ((p->chunks[i].chunk_id == RADEON_CHUNK_ID_RELOCS) ||
-                    (p->chunks[i].chunk_id == RADEON_CHUNK_ID_FLAGS)) {
-                        size = p->chunks[i].length_dw * sizeof(uint32_t);
-                        p->chunks[i].kdata = kmalloc(size, GFP_KERNEL);
-                        if (p->chunks[i].kdata == NULL) {
-                                return -ENOMEM;
-                        }
-                        if (DRM_COPY_FROM_USER(p->chunks[i].kdata,
-                                               p->chunks[i].user_ptr, size)) {
-                                return -EFAULT;
-                        }
-                        if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_FLAGS) {
-                                p->cs_flags = p->chunks[i].kdata[0];
-                                if (p->chunks[i].length_dw > 1)
-                                        ring = p->chunks[i].kdata[1];
-                                if (p->chunks[i].length_dw > 2)
-                                        priority = (s32)p->chunks[i].kdata[2];
-                        }
+                size = p->chunks[i].length_dw;
+                cdata = (void __user *)(unsigned long)user_chunk.chunk_data;
+                p->chunks[i].user_ptr = cdata;
+                if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_CONST_IB)
+                        continue;
+
+                if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_IB) {
+                        if (!p->rdev || !(p->rdev->flags & RADEON_IS_AGP))
+                                continue;
+                }
+
+                p->chunks[i].kdata = drm_malloc_ab(size, sizeof(uint32_t));
+                size *= sizeof(uint32_t);
+                if (p->chunks[i].kdata == NULL) {
+                        return -ENOMEM;
+                }
+                if (DRM_COPY_FROM_USER(p->chunks[i].kdata, cdata, size)) {
+                        return -EFAULT;
+                }
+                if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_FLAGS) {
+                        p->cs_flags = p->chunks[i].kdata[0];
+                        if (p->chunks[i].length_dw > 1)
+                                ring = p->chunks[i].kdata[1];
+                        if (p->chunks[i].length_dw > 2)
+                                priority = (s32)p->chunks[i].kdata[2];
                 }
         }
 
@@ -279,34 +283,6 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data)
                 }
         }
 
-        /* deal with non-vm */
-        if ((p->chunk_ib_idx != -1) &&
-            ((p->cs_flags & RADEON_CS_USE_VM) == 0) &&
-            (p->chunks[p->chunk_ib_idx].chunk_id == RADEON_CHUNK_ID_IB)) {
-                if (p->chunks[p->chunk_ib_idx].length_dw > (16 * 1024)) {
-                        DRM_ERROR("cs IB too big: %d\n",
-                                  p->chunks[p->chunk_ib_idx].length_dw);
-                        return -EINVAL;
-                }
-                if (p->rdev && (p->rdev->flags & RADEON_IS_AGP)) {
-                        p->chunks[p->chunk_ib_idx].kpage[0] = kmalloc(PAGE_SIZE, GFP_KERNEL);
-                        p->chunks[p->chunk_ib_idx].kpage[1] = kmalloc(PAGE_SIZE, GFP_KERNEL);
-                        if (p->chunks[p->chunk_ib_idx].kpage[0] == NULL ||
-                            p->chunks[p->chunk_ib_idx].kpage[1] == NULL) {
-                                kfree(p->chunks[p->chunk_ib_idx].kpage[0]);
-                                kfree(p->chunks[p->chunk_ib_idx].kpage[1]);
-                                p->chunks[p->chunk_ib_idx].kpage[0] = NULL;
-                                p->chunks[p->chunk_ib_idx].kpage[1] = NULL;
-                                return -ENOMEM;
-                        }
-                }
-                p->chunks[p->chunk_ib_idx].kpage_idx[0] = -1;
-                p->chunks[p->chunk_ib_idx].kpage_idx[1] = -1;
-                p->chunks[p->chunk_ib_idx].last_copied_page = -1;
-                p->chunks[p->chunk_ib_idx].last_page_index =
-                        ((p->chunks[p->chunk_ib_idx].length_dw * 4) - 1) / PAGE_SIZE;
-        }
-
         return 0;
 }
 
@@ -340,13 +316,8 @@ static void radeon_cs_parser_fini(struct radeon_cs_parser *parser, int error, bo
         kfree(parser->track);
         kfree(parser->relocs);
         kfree(parser->relocs_ptr);
-        for (i = 0; i < parser->nchunks; i++) {
-                kfree(parser->chunks[i].kdata);
-                if ((parser->rdev->flags & RADEON_IS_AGP)) {
-                        kfree(parser->chunks[i].kpage[0]);
-                        kfree(parser->chunks[i].kpage[1]);
-                }
-        }
+        for (i = 0; i < parser->nchunks; i++)
+                drm_free_large(parser->chunks[i].kdata);
         kfree(parser->chunks);
         kfree(parser->chunks_array);
         radeon_ib_free(parser->rdev, &parser->ib);
@@ -356,7 +327,6 @@ static void radeon_cs_parser_fini(struct radeon_cs_parser *parser, int error, bo
 static int radeon_cs_ib_chunk(struct radeon_device *rdev,
                               struct radeon_cs_parser *parser)
 {
-        struct radeon_cs_chunk *ib_chunk;
         int r;
 
         if (parser->chunk_ib_idx == -1)
@@ -365,28 +335,11 @@ static int radeon_cs_ib_chunk(struct radeon_device *rdev,
         if (parser->cs_flags & RADEON_CS_USE_VM)
                 return 0;
 
-        ib_chunk = &parser->chunks[parser->chunk_ib_idx];
-        /* Copy the packet into the IB, the parser will read from the
-         * input memory (cached) and write to the IB (which can be
-         * uncached).
-         */
-        r =  radeon_ib_get(rdev, parser->ring, &parser->ib,
-                           NULL, ib_chunk->length_dw * 4);
-        if (r) {
-                DRM_ERROR("Failed to get ib !\n");
-                return r;
-        }
-        parser->ib.length_dw = ib_chunk->length_dw;
         r = radeon_cs_parse(rdev, parser->ring, parser);
         if (r || parser->parser_error) {
                 DRM_ERROR("Invalid command stream !\n");
                 return r;
         }
-        r = radeon_cs_finish_pages(parser);
-        if (r) {
-                DRM_ERROR("Invalid command stream !\n");
-                return r;
-        }
 
         if (parser->ring == R600_RING_TYPE_UVD_INDEX)
                 radeon_uvd_note_usage(rdev);
@@ -424,7 +377,6 @@ static int radeon_bo_vm_update_pte(struct radeon_cs_parser *parser,
 static int radeon_cs_ib_vm_chunk(struct radeon_device *rdev,
                                  struct radeon_cs_parser *parser)
 {
-        struct radeon_cs_chunk *ib_chunk;
         struct radeon_fpriv *fpriv = parser->filp->driver_priv;
         struct radeon_vm *vm = &fpriv->vm;
         int r;
@@ -434,49 +386,13 @@ static int radeon_cs_ib_vm_chunk(struct radeon_device *rdev,
         if ((parser->cs_flags & RADEON_CS_USE_VM) == 0)
                 return 0;
 
-        if ((rdev->family >= CHIP_TAHITI) &&
-            (parser->chunk_const_ib_idx != -1)) {
-                ib_chunk = &parser->chunks[parser->chunk_const_ib_idx];
-                if (ib_chunk->length_dw > RADEON_IB_VM_MAX_SIZE) {
-                        DRM_ERROR("cs IB CONST too big: %d\n", ib_chunk->length_dw);
-                        return -EINVAL;
-                }
-                r =  radeon_ib_get(rdev, parser->ring, &parser->const_ib,
-                                   vm, ib_chunk->length_dw * 4);
-                if (r) {
-                        DRM_ERROR("Failed to get const ib !\n");
-                        return r;
-                }
-                parser->const_ib.is_const_ib = true;
-                parser->const_ib.length_dw = ib_chunk->length_dw;
-                /* Copy the packet into the IB */
-                if (DRM_COPY_FROM_USER(parser->const_ib.ptr, ib_chunk->user_ptr,
-                                       ib_chunk->length_dw * 4)) {
-                        return -EFAULT;
-                }
+        if (parser->const_ib.length_dw) {
                 r = radeon_ring_ib_parse(rdev, parser->ring, &parser->const_ib);
                 if (r) {
                         return r;
                 }
         }
 
-        ib_chunk = &parser->chunks[parser->chunk_ib_idx];
-        if (ib_chunk->length_dw > RADEON_IB_VM_MAX_SIZE) {
-                DRM_ERROR("cs IB too big: %d\n", ib_chunk->length_dw);
-                return -EINVAL;
-        }
-        r =  radeon_ib_get(rdev, parser->ring, &parser->ib,
-                           vm, ib_chunk->length_dw * 4);
-        if (r) {
-                DRM_ERROR("Failed to get ib !\n");
-                return r;
-        }
-        parser->ib.length_dw = ib_chunk->length_dw;
-        /* Copy the packet into the IB */
-        if (DRM_COPY_FROM_USER(parser->ib.ptr, ib_chunk->user_ptr,
-                               ib_chunk->length_dw * 4)) {
-                return -EFAULT;
-        }
         r = radeon_ring_ib_parse(rdev, parser->ring, &parser->ib);
         if (r) {
                 return r;
@@ -528,6 +444,62 @@ static int radeon_cs_handle_lockup(struct radeon_device *rdev, int r)
         return r;
 }
 
+static int radeon_cs_ib_fill(struct radeon_device *rdev, struct radeon_cs_parser *parser)
+{
+        struct radeon_cs_chunk *ib_chunk;
+        struct radeon_vm *vm = NULL;
+        int r;
+
+        if (parser->chunk_ib_idx == -1)
+                return 0;
+
+        if (parser->cs_flags & RADEON_CS_USE_VM) {
+                struct radeon_fpriv *fpriv = parser->filp->driver_priv;
+                vm = &fpriv->vm;
+
+                if ((rdev->family >= CHIP_TAHITI) &&
+                    (parser->chunk_const_ib_idx != -1)) {
+                        ib_chunk = &parser->chunks[parser->chunk_const_ib_idx];
+                        if (ib_chunk->length_dw > RADEON_IB_VM_MAX_SIZE) {
+                                DRM_ERROR("cs IB CONST too big: %d\n", ib_chunk->length_dw);
+                                return -EINVAL;
+                        }
+                        r =  radeon_ib_get(rdev, parser->ring, &parser->const_ib,
+                                           vm, ib_chunk->length_dw * 4);
+                        if (r) {
+                                DRM_ERROR("Failed to get const ib !\n");
+                                return r;
+                        }
+                        parser->const_ib.is_const_ib = true;
+                        parser->const_ib.length_dw = ib_chunk->length_dw;
+                        if (DRM_COPY_FROM_USER(parser->const_ib.ptr,
+                                               ib_chunk->user_ptr,
+                                               ib_chunk->length_dw * 4))
+                                return -EFAULT;
+                }
+
+                ib_chunk = &parser->chunks[parser->chunk_ib_idx];
+                if (ib_chunk->length_dw > RADEON_IB_VM_MAX_SIZE) {
+                        DRM_ERROR("cs IB too big: %d\n", ib_chunk->length_dw);
+                        return -EINVAL;
+                }
+        }
+        ib_chunk = &parser->chunks[parser->chunk_ib_idx];
+
+        r =  radeon_ib_get(rdev, parser->ring, &parser->ib,
+                           vm, ib_chunk->length_dw * 4);
+        if (r) {
+                DRM_ERROR("Failed to get ib !\n");
+                return r;
+        }
+        parser->ib.length_dw = ib_chunk->length_dw;
+        if (ib_chunk->kdata)
+                memcpy(parser->ib.ptr, ib_chunk->kdata, ib_chunk->length_dw * 4);
+        else if (DRM_COPY_FROM_USER(parser->ib.ptr, ib_chunk->user_ptr, ib_chunk->length_dw * 4))
+                return -EFAULT;
+        return 0;
+}
+
 int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 {
         struct radeon_device *rdev = dev->dev_private;
@@ -553,10 +525,15 @@ int radeon_cs_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
                 r = radeon_cs_handle_lockup(rdev, r);
                 return r;
         }
-        r = radeon_cs_parser_relocs(&parser);
-        if (r) {
-                if (r != -ERESTARTSYS)
+
+        r = radeon_cs_ib_fill(rdev, &parser);
+        if (!r) {
+                r = radeon_cs_parser_relocs(&parser);
+                if (r && r != -ERESTARTSYS)
                         DRM_ERROR("Failed to parse relocation %d!\n", r);
+        }
+
+        if (r) {
                 radeon_cs_parser_fini(&parser, r, false);
                 up_read(&rdev->exclusive_lock);
                 r = radeon_cs_handle_lockup(rdev, r);
@@ -580,97 +557,6 @@ out:
         return r;
 }
 
-int radeon_cs_finish_pages(struct radeon_cs_parser *p)
-{
-        struct radeon_cs_chunk *ibc = &p->chunks[p->chunk_ib_idx];
-        int i;
-        int size = PAGE_SIZE;
-
-        for (i = ibc->last_copied_page + 1; i <= ibc->last_page_index; i++) {
-                if (i == ibc->last_page_index) {
-                        size = (ibc->length_dw * 4) % PAGE_SIZE;
-                        if (size == 0)
-                                size = PAGE_SIZE;
-                }
-                
-                if (DRM_COPY_FROM_USER(p->ib.ptr + (i * (PAGE_SIZE/4)),
-                                       ibc->user_ptr + (i * PAGE_SIZE),
-                                       size))
-                        return -EFAULT;
-        }
-        return 0;
-}
-
-static int radeon_cs_update_pages(struct radeon_cs_parser *p, int pg_idx)
-{
-        int new_page;
-        struct radeon_cs_chunk *ibc = &p->chunks[p->chunk_ib_idx];
-        int i;
-        int size = PAGE_SIZE;
-        bool copy1 = (p->rdev && (p->rdev->flags & RADEON_IS_AGP)) ?
-                false : true;
-
-        for (i = ibc->last_copied_page + 1; i < pg_idx; i++) {
-                if (DRM_COPY_FROM_USER(p->ib.ptr + (i * (PAGE_SIZE/4)),
-                                       ibc->user_ptr + (i * PAGE_SIZE),
-                                       PAGE_SIZE)) {
-                        p->parser_error = -EFAULT;
-                        return 0;
-                }
-        }
-
-        if (pg_idx == ibc->last_page_index) {
-                size = (ibc->length_dw * 4) % PAGE_SIZE;
-                if (size == 0)
-                        size = PAGE_SIZE;
-        }
-
-        new_page = ibc->kpage_idx[0] < ibc->kpage_idx[1] ? 0 : 1;
-        if (copy1)
-                ibc->kpage[new_page] = p->ib.ptr + (pg_idx * (PAGE_SIZE / 4));
-
-        if (DRM_COPY_FROM_USER(ibc->kpage[new_page],
-                               ibc->user_ptr + (pg_idx * PAGE_SIZE),
-                               size)) {
-                p->parser_error = -EFAULT;
-                return 0;
-        }
-
-        /* copy to IB for non single case */
-        if (!copy1)
-                memcpy((void *)(p->ib.ptr+(pg_idx*(PAGE_SIZE/4))), ibc->kpage[new_page], size);
-
-        ibc->last_copied_page = pg_idx;
-        ibc->kpage_idx[new_page] = pg_idx;
-
-        return new_page;
-}
-
-u32 radeon_get_ib_value(struct radeon_cs_parser *p, int idx)
-{
-        struct radeon_cs_chunk *ibc = &p->chunks[p->chunk_ib_idx];
-        u32 pg_idx, pg_offset;
-        u32 idx_value = 0;
-        int new_page;
-
-        pg_idx = (idx * 4) / PAGE_SIZE;
-        pg_offset = (idx * 4) % PAGE_SIZE;
-
-        if (ibc->kpage_idx[0] == pg_idx)
-                return ibc->kpage[0][pg_offset/4];
-        if (ibc->kpage_idx[1] == pg_idx)
-                return ibc->kpage[1][pg_offset/4];
-
-        new_page = radeon_cs_update_pages(p, pg_idx);
-        if (new_page < 0) {
-                p->parser_error = new_page;
-                return 0;
-        }
-
-        idx_value = ibc->kpage[new_page][pg_offset/4];
-        return idx_value;
-}
-
 /**
  * radeon_cs_packet_parse() - parse cp packet and point ib index to next packet
  * @parser:     parser structure holding parsing context.