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drm/radeon: use mmu_notifier_get/put for struct radeon_mn 

radeon is using a device global hash table to track what mmu_notifiers
have been registered on struct mm. This is better served with the new
get/put scheme instead.

radeon has a bug where it was not blocking notifier release() until all
the BO's had been invalidated. This could result in a use after free of
pages the BOs. This is tied into a second bug where radeon left the
notifiers running endlessly even once the interval tree became
empty. This could result in a use after free with module unload.

Both are fixed by changing the lifetime model, the BOs exist in the
interval tree with their natural lifetimes independent of the mm_struct
lifetime using the get/put scheme. The release runs synchronously and just
does invalidate_start across the entire interval tree to create the
required DMA fence.

Additions to the interval tree after release are already impossible as
only current->mm is used during the add.

Link: https://lore.kernel.org/r/20190806231548.25242-9-jgg@ziepe.ca
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2019-08-06 20:15:45 -03:00
parent c7d8b7824f
commit 534e5f84b7
4 changed files with 44 additions and 132 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/gpu/drm/radeon/radeon.h
View File

@ -2451,9 +2451,6 @@ struct radeon_device {
/* tracking pinned memory */
u64 vram_pin_size;
u64 gart_pin_size;
struct mutex mn_lock;
DECLARE_HASHTABLE(mn_hash, 7);
};
bool radeon_is_px(struct drm_device *dev);

2
drivers/gpu/drm/radeon/radeon_device.c
View File

@ -1325,8 +1325,6 @@ int radeon_device_init(struct radeon_device *rdev,
init_rwsem(&rdev->pm.mclk_lock);
init_rwsem(&rdev->exclusive_lock);
init_waitqueue_head(&rdev->irq.vblank_queue);
mutex_init(&rdev->mn_lock);
hash_init(rdev->mn_hash);
r = radeon_gem_init(rdev);
if (r)
return r;

2
drivers/gpu/drm/radeon/radeon_drv.c
View File

@ -35,6 +35,7 @@
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/vga_switcheroo.h>
#include <linux/mmu_notifier.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_drv.h>
@ -624,6 +625,7 @@ static void __exit radeon_exit(void)
{
pci_unregister_driver(pdriver);
radeon_unregister_atpx_handler();
mmu_notifier_synchronize();
}
module_init(radeon_init);

169
drivers/gpu/drm/radeon/radeon_mn.c
View File

@ -37,17 +37,8 @@
#include "radeon.h"
struct radeon_mn {
/* constant after initialisation */
struct radeon_device *rdev;
struct mm_struct *mm;
struct mmu_notifier mn;
/* only used on destruction */
struct work_struct work;
/* protected by rdev->mn_lock */
struct hlist_node node;
/* objects protected by lock */
struct mutex lock;
struct rb_root_cached objects;
@ -58,55 +49,6 @@ struct radeon_mn_node {
struct list_head bos;
};
/**
* radeon_mn_destroy - destroy the rmn
*
* @work: previously sheduled work item
*
* Lazy destroys the notifier from a work item
*/
static void radeon_mn_destroy(struct work_struct *work)
{
struct radeon_mn *rmn = container_of(work, struct radeon_mn, work);
struct radeon_device *rdev = rmn->rdev;
struct radeon_mn_node *node, *next_node;
struct radeon_bo *bo, *next_bo;
mutex_lock(&rdev->mn_lock);
mutex_lock(&rmn->lock);
hash_del(&rmn->node);
rbtree_postorder_for_each_entry_safe(node, next_node,
&rmn->objects.rb_root, it.rb) {
interval_tree_remove(&node->it, &rmn->objects);
list_for_each_entry_safe(bo, next_bo, &node->bos, mn_list) {
bo->mn = NULL;
list_del_init(&bo->mn_list);
}
kfree(node);
}
mutex_unlock(&rmn->lock);
mutex_unlock(&rdev->mn_lock);
mmu_notifier_unregister(&rmn->mn, rmn->mm);
kfree(rmn);
}
/**
* radeon_mn_release - callback to notify about mm destruction
*
* @mn: our notifier
* @mn: the mm this callback is about
*
* Shedule a work item to lazy destroy our notifier.
*/
static void radeon_mn_release(struct mmu_notifier *mn,
struct mm_struct *mm)
{
struct radeon_mn *rmn = container_of(mn, struct radeon_mn, mn);
INIT_WORK(&rmn->work, radeon_mn_destroy);
schedule_work(&rmn->work);
}
/**
* radeon_mn_invalidate_range_start - callback to notify about mm change
*
@ -183,65 +125,44 @@ static int radeon_mn_invalidate_range_start(struct mmu_notifier *mn,
return ret;
}
static void radeon_mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct mmu_notifier_range range = {
.mm = mm,
.start = 0,
.end = ULONG_MAX,
.flags = 0,
.event = MMU_NOTIFY_UNMAP,
};
radeon_mn_invalidate_range_start(mn, &range);
}
static struct mmu_notifier *radeon_mn_alloc_notifier(struct mm_struct *mm)
{
struct radeon_mn *rmn;
rmn = kzalloc(sizeof(*rmn), GFP_KERNEL);
if (!rmn)
return ERR_PTR(-ENOMEM);
mutex_init(&rmn->lock);
rmn->objects = RB_ROOT_CACHED;
return &rmn->mn;
}
static void radeon_mn_free_notifier(struct mmu_notifier *mn)
{
kfree(container_of(mn, struct radeon_mn, mn));
}
static const struct mmu_notifier_ops radeon_mn_ops = {
.release = radeon_mn_release,
.invalidate_range_start = radeon_mn_invalidate_range_start,
.alloc_notifier = radeon_mn_alloc_notifier,
.free_notifier = radeon_mn_free_notifier,
};
/**
* radeon_mn_get - create notifier context
*
* @rdev: radeon device pointer
*
* Creates a notifier context for current->mm.
*/
static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)
{
struct mm_struct *mm = current->mm;
struct radeon_mn *rmn;
int r;
if (down_write_killable(&mm->mmap_sem))
return ERR_PTR(-EINTR);
mutex_lock(&rdev->mn_lock);
hash_for_each_possible(rdev->mn_hash, rmn, node, (unsigned long)mm)
if (rmn->mm == mm)
goto release_locks;
rmn = kzalloc(sizeof(*rmn), GFP_KERNEL);
if (!rmn) {
rmn = ERR_PTR(-ENOMEM);
goto release_locks;
}
rmn->rdev = rdev;
rmn->mm = mm;
rmn->mn.ops = &radeon_mn_ops;
mutex_init(&rmn->lock);
rmn->objects = RB_ROOT_CACHED;
r = __mmu_notifier_register(&rmn->mn, mm);
if (r)
goto free_rmn;
hash_add(rdev->mn_hash, &rmn->node, (unsigned long)mm);
release_locks:
mutex_unlock(&rdev->mn_lock);
up_write(&mm->mmap_sem);
return rmn;
free_rmn:
mutex_unlock(&rdev->mn_lock);
up_write(&mm->mmap_sem);
kfree(rmn);
return ERR_PTR(r);
}
/**
* radeon_mn_register - register a BO for notifier updates
*
@ -254,15 +175,16 @@ static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)
int radeon_mn_register(struct radeon_bo *bo, unsigned long addr)
{
unsigned long end = addr + radeon_bo_size(bo) - 1;
struct radeon_device *rdev = bo->rdev;
struct mmu_notifier *mn;
struct radeon_mn *rmn;
struct radeon_mn_node *node = NULL;
struct list_head bos;
struct interval_tree_node *it;
rmn = radeon_mn_get(rdev);
if (IS_ERR(rmn))
return PTR_ERR(rmn);
mn = mmu_notifier_get(&radeon_mn_ops, current->mm);
if (IS_ERR(mn))
return PTR_ERR(mn);
rmn = container_of(mn, struct radeon_mn, mn);
INIT_LIST_HEAD(&bos);
@ -309,22 +231,13 @@ int radeon_mn_register(struct radeon_bo *bo, unsigned long addr)
*/
void radeon_mn_unregister(struct radeon_bo *bo)
{
struct radeon_device *rdev = bo->rdev;
struct radeon_mn *rmn;
struct radeon_mn *rmn = bo->mn;
struct list_head *head;
mutex_lock(&rdev->mn_lock);
rmn = bo->mn;
if (rmn == NULL) {
mutex_unlock(&rdev->mn_lock);
return;
}
mutex_lock(&rmn->lock);
/* save the next list entry for later */
head = bo->mn_list.next;
bo->mn = NULL;
list_del(&bo->mn_list);
if (list_empty(head)) {
@ -335,5 +248,7 @@ void radeon_mn_unregister(struct radeon_bo *bo)
}
mutex_unlock(&rmn->lock);
mutex_unlock(&rdev->mn_lock);
mmu_notifier_put(&rmn->mn);
bo->mn = NULL;
}