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drm/i915: Always use kref tracking for all contexts.

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If we always initialize kref for the context, even if we are using fake
contexts for hangstats when there is no hw support, we can forgo the
dance to dereference the ctx->obj and inspect whether we are permitted
to use kref inside i915_gem_context_reference() and _unreference().

My ulterior motive here is to improve the debugging of a use-after-free
of ctx->obj. This patch avoids the dereference here and instead forces
the assertion checks associated with kref.

v2: Refactor the fake contexts to being even more like the real
contexts, so that there is much less duplicated and special case code.

v3: Tweaks.
v4: Tweaks, minor.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76671
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: lu hua <huax.lu@intel.com>
Cc: Ben Widawsky <benjamin.widawsky@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
[Jani: tiny change to backport to drm-intel-fixes.]
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2014-04-09 09:07:36 +01:00 committed by Jani Nikula
parent c675949ec5
commit 691e6415c8
4 changed files with 94 additions and 138 deletions
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8
drivers/gpu/drm/i915/i915_drv.h
View File

@ -2432,20 +2432,18 @@ int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
int i915_gem_context_enable(struct drm_i915_private *dev_priv);
void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
int i915_switch_context(struct intel_ring_buffer *ring,
struct drm_file *file, struct i915_hw_context *to);
struct i915_hw_context *to);
struct i915_hw_context *
i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id);
void i915_gem_context_free(struct kref *ctx_ref);
static inline void i915_gem_context_reference(struct i915_hw_context *ctx)
{
if (ctx->obj && HAS_HW_CONTEXTS(ctx->obj->base.dev))
kref_get(&ctx->ref);
kref_get(&ctx->ref);
}
static inline void i915_gem_context_unreference(struct i915_hw_context *ctx)
{
if (ctx->obj && HAS_HW_CONTEXTS(ctx->obj->base.dev))
kref_put(&ctx->ref, i915_gem_context_free);
kref_put(&ctx->ref, i915_gem_context_free);
}
static inline bool i915_gem_context_is_default(const struct i915_hw_context *c)

2
drivers/gpu/drm/i915/i915_gem.c
View File

@ -2790,7 +2790,7 @@ int i915_gpu_idle(struct drm_device *dev)
/* Flush everything onto the inactive list. */
for_each_ring(ring, dev_priv, i) {
ret = i915_switch_context(ring, NULL, ring->default_context);
ret = i915_switch_context(ring, ring->default_context);
if (ret)
return ret;

220
drivers/gpu/drm/i915/i915_gem_context.c
View File

@ -96,9 +96,6 @@
#define GEN6_CONTEXT_ALIGN (64<<10)
#define GEN7_CONTEXT_ALIGN 4096
static int do_switch(struct intel_ring_buffer *ring,
struct i915_hw_context *to);
static void do_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
{
struct drm_device *dev = ppgtt->base.dev;
@ -185,13 +182,15 @@ void i915_gem_context_free(struct kref *ctx_ref)
typeof(*ctx), ref);
struct i915_hw_ppgtt *ppgtt = NULL;
/* We refcount even the aliasing PPGTT to keep the code symmetric */
if (USES_PPGTT(ctx->obj->base.dev))
ppgtt = ctx_to_ppgtt(ctx);
if (ctx->obj) {
/* We refcount even the aliasing PPGTT to keep the code symmetric */
if (USES_PPGTT(ctx->obj->base.dev))
ppgtt = ctx_to_ppgtt(ctx);
/* XXX: Free up the object before tearing down the address space, in
* case we're bound in the PPGTT */
drm_gem_object_unreference(&ctx->obj->base);
/* XXX: Free up the object before tearing down the address space, in
* case we're bound in the PPGTT */
drm_gem_object_unreference(&ctx->obj->base);
}
if (ppgtt)
kref_put(&ppgtt->ref, ppgtt_release);
@ -232,32 +231,32 @@ __create_hw_context(struct drm_device *dev,
return ERR_PTR(-ENOMEM);
kref_init(&ctx->ref);
ctx->obj = i915_gem_alloc_object(dev, dev_priv->hw_context_size);
INIT_LIST_HEAD(&ctx->link);
if (ctx->obj == NULL) {
kfree(ctx);
DRM_DEBUG_DRIVER("Context object allocated failed\n");
return ERR_PTR(-ENOMEM);
}
if (INTEL_INFO(dev)->gen >= 7) {
ret = i915_gem_object_set_cache_level(ctx->obj,
I915_CACHE_L3_LLC);
/* Failure shouldn't ever happen this early */
if (WARN_ON(ret))
goto err_out;
}
list_add_tail(&ctx->link, &dev_priv->context_list);
/* Default context will never have a file_priv */
if (file_priv == NULL)
return ctx;
if (dev_priv->hw_context_size) {
ctx->obj = i915_gem_alloc_object(dev, dev_priv->hw_context_size);
if (ctx->obj == NULL) {
ret = -ENOMEM;
goto err_out;
}
ret = idr_alloc(&file_priv->context_idr, ctx, DEFAULT_CONTEXT_ID, 0,
GFP_KERNEL);
if (ret < 0)
goto err_out;
if (INTEL_INFO(dev)->gen >= 7) {
ret = i915_gem_object_set_cache_level(ctx->obj,
I915_CACHE_L3_LLC);
/* Failure shouldn't ever happen this early */
if (WARN_ON(ret))
goto err_out;
}
}
/* Default context will never have a file_priv */
if (file_priv != NULL) {
ret = idr_alloc(&file_priv->context_idr, ctx,
DEFAULT_CONTEXT_ID, 0, GFP_KERNEL);
if (ret < 0)
goto err_out;
} else
ret = DEFAULT_CONTEXT_ID;
ctx->file_priv = file_priv;
ctx->id = ret;
@ -294,7 +293,7 @@ i915_gem_create_context(struct drm_device *dev,
if (IS_ERR(ctx))
return ctx;
if (is_global_default_ctx) {
if (is_global_default_ctx && ctx->obj) {
/* We may need to do things with the shrinker which
* require us to immediately switch back to the default
* context. This can cause a problem as pinning the
@ -342,7 +341,7 @@ i915_gem_create_context(struct drm_device *dev,
return ctx;
err_unpin:
if (is_global_default_ctx)
if (is_global_default_ctx && ctx->obj)
i915_gem_object_ggtt_unpin(ctx->obj);
err_destroy:
i915_gem_context_unreference(ctx);
@ -352,32 +351,22 @@ i915_gem_create_context(struct drm_device *dev,
void i915_gem_context_reset(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_ring_buffer *ring;
int i;
if (!HAS_HW_CONTEXTS(dev))
return;
/* Prevent the hardware from restoring the last context (which hung) on
* the next switch */
for (i = 0; i < I915_NUM_RINGS; i++) {
struct i915_hw_context *dctx;
if (!(INTEL_INFO(dev)->ring_mask & (1<<i)))
continue;
struct intel_ring_buffer *ring = &dev_priv->ring[i];
struct i915_hw_context *dctx = ring->default_context;
/* Do a fake switch to the default context */
ring = &dev_priv->ring[i];
dctx = ring->default_context;
if (WARN_ON(!dctx))
if (ring->last_context == dctx)
continue;
if (!ring->last_context)
continue;
if (ring->last_context == dctx)
continue;
if (i == RCS) {
if (dctx->obj && i == RCS) {
WARN_ON(i915_gem_obj_ggtt_pin(dctx->obj,
get_context_alignment(dev), 0));
/* Fake a finish/inactive */
@ -394,44 +383,35 @@ void i915_gem_context_reset(struct drm_device *dev)
int i915_gem_context_init(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_ring_buffer *ring;
struct i915_hw_context *ctx;
int i;
if (!HAS_HW_CONTEXTS(dev))
return 0;
/* Init should only be called once per module load. Eventually the
* restriction on the context_disabled check can be loosened. */
if (WARN_ON(dev_priv->ring[RCS].default_context))
return 0;
dev_priv->hw_context_size = round_up(get_context_size(dev), 4096);
if (dev_priv->hw_context_size > (1<<20)) {
DRM_DEBUG_DRIVER("Disabling HW Contexts; invalid size\n");
return -E2BIG;
if (HAS_HW_CONTEXTS(dev)) {
dev_priv->hw_context_size = round_up(get_context_size(dev), 4096);
if (dev_priv->hw_context_size > (1<<20)) {
DRM_DEBUG_DRIVER("Disabling HW Contexts; invalid size %d\n",
dev_priv->hw_context_size);
dev_priv->hw_context_size = 0;
}
}
dev_priv->ring[RCS].default_context =
i915_gem_create_context(dev, NULL, USES_PPGTT(dev));
if (IS_ERR_OR_NULL(dev_priv->ring[RCS].default_context)) {
DRM_DEBUG_DRIVER("Disabling HW Contexts; create failed %ld\n",
PTR_ERR(dev_priv->ring[RCS].default_context));
return PTR_ERR(dev_priv->ring[RCS].default_context);
ctx = i915_gem_create_context(dev, NULL, USES_PPGTT(dev));
if (IS_ERR(ctx)) {
DRM_ERROR("Failed to create default global context (error %ld)\n",
PTR_ERR(ctx));
return PTR_ERR(ctx);
}
for (i = RCS + 1; i < I915_NUM_RINGS; i++) {
if (!(INTEL_INFO(dev)->ring_mask & (1<<i)))
continue;
/* NB: RCS will hold a ref for all rings */
for (i = 0; i < I915_NUM_RINGS; i++)
dev_priv->ring[i].default_context = ctx;
ring = &dev_priv->ring[i];
/* NB: RCS will hold a ref for all rings */
ring->default_context = dev_priv->ring[RCS].default_context;
}
DRM_DEBUG_DRIVER("HW context support initialized\n");
DRM_DEBUG_DRIVER("%s context support initialized\n", dev_priv->hw_context_size ? "HW" : "fake");
return 0;
}
@ -441,33 +421,30 @@ void i915_gem_context_fini(struct drm_device *dev)
struct i915_hw_context *dctx = dev_priv->ring[RCS].default_context;
int i;
if (!HAS_HW_CONTEXTS(dev))
return;
if (dctx->obj) {
/* The only known way to stop the gpu from accessing the hw context is
* to reset it. Do this as the very last operation to avoid confusing
* other code, leading to spurious errors. */
intel_gpu_reset(dev);
/* The only known way to stop the gpu from accessing the hw context is
* to reset it. Do this as the very last operation to avoid confusing
* other code, leading to spurious errors. */
intel_gpu_reset(dev);
/* When default context is created and switched to, base object refcount
* will be 2 (+1 from object creation and +1 from do_switch()).
* i915_gem_context_fini() will be called after gpu_idle() has switched
* to default context. So we need to unreference the base object once
* to offset the do_switch part, so that i915_gem_context_unreference()
* can then free the base object correctly. */
WARN_ON(!dev_priv->ring[RCS].last_context);
if (dev_priv->ring[RCS].last_context == dctx) {
/* Fake switch to NULL context */
WARN_ON(dctx->obj->active);
i915_gem_object_ggtt_unpin(dctx->obj);
i915_gem_context_unreference(dctx);
dev_priv->ring[RCS].last_context = NULL;
/* When default context is created and switched to, base object refcount
* will be 2 (+1 from object creation and +1 from do_switch()).
* i915_gem_context_fini() will be called after gpu_idle() has switched
* to default context. So we need to unreference the base object once
* to offset the do_switch part, so that i915_gem_context_unreference()
* can then free the base object correctly. */
WARN_ON(!dev_priv->ring[RCS].last_context);
if (dev_priv->ring[RCS].last_context == dctx) {
/* Fake switch to NULL context */
WARN_ON(dctx->obj->active);
i915_gem_object_ggtt_unpin(dctx->obj);
i915_gem_context_unreference(dctx);
dev_priv->ring[RCS].last_context = NULL;
}
}
for (i = 0; i < I915_NUM_RINGS; i++) {
struct intel_ring_buffer *ring = &dev_priv->ring[i];
if (!(INTEL_INFO(dev)->ring_mask & (1<<i)))
continue;
if (ring->last_context)
i915_gem_context_unreference(ring->last_context);
@ -478,7 +455,6 @@ void i915_gem_context_fini(struct drm_device *dev)
i915_gem_object_ggtt_unpin(dctx->obj);
i915_gem_context_unreference(dctx);
dev_priv->mm.aliasing_ppgtt = NULL;
}
int i915_gem_context_enable(struct drm_i915_private *dev_priv)
@ -486,9 +462,6 @@ int i915_gem_context_enable(struct drm_i915_private *dev_priv)
struct intel_ring_buffer *ring;
int ret, i;
if (!HAS_HW_CONTEXTS(dev_priv->dev))
return 0;
/* This is the only place the aliasing PPGTT gets enabled, which means
* it has to happen before we bail on reset */
if (dev_priv->mm.aliasing_ppgtt) {
@ -503,7 +476,7 @@ int i915_gem_context_enable(struct drm_i915_private *dev_priv)
BUG_ON(!dev_priv->ring[RCS].default_context);
for_each_ring(ring, dev_priv, i) {
ret = do_switch(ring, ring->default_context);
ret = i915_switch_context(ring, ring->default_context);
if (ret)
return ret;
}
@ -526,19 +499,6 @@ static int context_idr_cleanup(int id, void *p, void *data)
int i915_gem_context_open(struct drm_device *dev, struct drm_file *file)
{
struct drm_i915_file_private *file_priv = file->driver_priv;
struct drm_i915_private *dev_priv = dev->dev_private;
if (!HAS_HW_CONTEXTS(dev)) {
/* Cheat for hang stats */
file_priv->private_default_ctx =
kzalloc(sizeof(struct i915_hw_context), GFP_KERNEL);
if (file_priv->private_default_ctx == NULL)
return -ENOMEM;
file_priv->private_default_ctx->vm = &dev_priv->gtt.base;
return 0;
}
idr_init(&file_priv->context_idr);
@ -559,14 +519,10 @@ void i915_gem_context_close(struct drm_device *dev, struct drm_file *file)
{
struct drm_i915_file_private *file_priv = file->driver_priv;
if (!HAS_HW_CONTEXTS(dev)) {
kfree(file_priv->private_default_ctx);
return;
}
idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL);
i915_gem_context_unreference(file_priv->private_default_ctx);
idr_destroy(&file_priv->context_idr);
i915_gem_context_unreference(file_priv->private_default_ctx);
}
struct i915_hw_context *
@ -574,9 +530,6 @@ i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id)
{
struct i915_hw_context *ctx;
if (!HAS_HW_CONTEXTS(file_priv->dev_priv->dev))
return file_priv->private_default_ctx;
ctx = (struct i915_hw_context *)idr_find(&file_priv->context_idr, id);
if (!ctx)
return ERR_PTR(-ENOENT);
@ -758,7 +711,6 @@ static int do_switch(struct intel_ring_buffer *ring,
/**
* i915_switch_context() - perform a GPU context switch.
* @ring: ring for which we'll execute the context switch
* @file_priv: file_priv associated with the context, may be NULL
* @to: the context to switch to
*
* The context life cycle is simple. The context refcount is incremented and
@ -767,24 +719,30 @@ static int do_switch(struct intel_ring_buffer *ring,
* object while letting the normal object tracking destroy the backing BO.
*/
int i915_switch_context(struct intel_ring_buffer *ring,
struct drm_file *file,
struct i915_hw_context *to)
{
struct drm_i915_private *dev_priv = ring->dev->dev_private;
WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
BUG_ON(file && to == NULL);
/* We have the fake context */
if (!HAS_HW_CONTEXTS(ring->dev)) {
ring->last_context = to;
if (to->obj == NULL) { /* We have the fake context */
if (to != ring->last_context) {
i915_gem_context_reference(to);
if (ring->last_context)
i915_gem_context_unreference(ring->last_context);
ring->last_context = to;
}
return 0;
}
return do_switch(ring, to);
}
static bool hw_context_enabled(struct drm_device *dev)
{
return to_i915(dev)->hw_context_size;
}
int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
struct drm_file *file)
{
@ -793,7 +751,7 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
struct i915_hw_context *ctx;
int ret;
if (!HAS_HW_CONTEXTS(dev))
if (!hw_context_enabled(dev))
return -ENODEV;
ret = i915_mutex_lock_interruptible(dev);

2
drivers/gpu/drm/i915/i915_gem_execbuffer.c
View File

@ -1221,7 +1221,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
if (ret)
goto err;
ret = i915_switch_context(ring, file, ctx);
ret = i915_switch_context(ring, ctx);
if (ret)
goto err;