zircon/kernel/object/vm_object_dispatcher.cc - fuchsia - Git at Google

 // Copyright 2016 The Fuchsia Authors
 //
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT

 #include "object/vm_object_dispatcher.h"

 #include <assert.h>
 #include <inttypes.h>
 #include <lib/boot-options/boot-options.h>
 #include <lib/counters.h>
 #include <trace.h>
 #include <zircon/errors.h>
 #include <zircon/rights.h>

 #include <fbl/alloc_checker.h>
 #include <ktl/algorithm.h>
 #include <ktl/atomic.h>
 #include <ktl/optional.h>
 #include <vm/page_source.h>
 #include <vm/vm_aspace.h>
 #include <vm/vm_object.h>
 #include <vm/vm_object_paged.h>

 #include <ktl/enforce.h>

 #define LOCAL_TRACE 0

 KCOUNTER(dispatcher_vmo_create_count, "dispatcher.vmo.create")
 KCOUNTER(dispatcher_vmo_destroy_count, "dispatcher.vmo.destroy")

 zx_status_t VmObjectDispatcher::parse_create_syscall_flags(uint32_t flags, uint32_t* out_flags) {
   uint32_t res = 0;
   if (flags & ZX_VMO_RESIZABLE) {
     res |= VmObjectPaged::kResizable;
     flags &= ~ZX_VMO_RESIZABLE;
   }
   if (flags & ZX_VMO_DISCARDABLE) {
     res |= VmObjectPaged::kDiscardable;
     flags &= ~ZX_VMO_DISCARDABLE;
   }

   if (flags) {
     return ZX_ERR_INVALID_ARGS;
   }

   *out_flags = res;

   return ZX_OK;
 }

 zx_status_t VmObjectDispatcher::Create(fbl::RefPtr<VmObject> vmo, uint64_t content_size,
                                        zx_koid_t pager_koid, InitialMutability initial_mutability,
                                        KernelHandle<VmObjectDispatcher>* handle,
                                        zx_rights_t* rights) {
   fbl::AllocChecker ac;
   KernelHandle new_handle(fbl::AdoptRef(
       new (&ac) VmObjectDispatcher(ktl::move(vmo), content_size, pager_koid, initial_mutability)));
   if (!ac.check())
     return ZX_ERR_NO_MEMORY;

   new_handle.dispatcher()->vmo()->set_user_id(new_handle.dispatcher()->get_koid());
   *rights = default_rights();
   *handle = ktl::move(new_handle);
   return ZX_OK;
 }

 VmObjectDispatcher::VmObjectDispatcher(fbl::RefPtr<VmObject> vmo, uint64_t content_size,
                                        zx_koid_t pager_koid, InitialMutability initial_mutability)
     : SoloDispatcher(ZX_VMO_ZERO_CHILDREN),
       vmo_(ktl::move(vmo)),
       content_size_mgr_(content_size),
       pager_koid_(pager_koid),
       initial_mutability_(initial_mutability) {
   kcounter_add(dispatcher_vmo_create_count, 1);
   vmo_->SetChildObserver(this);
 }

 VmObjectDispatcher::~VmObjectDispatcher() {
   kcounter_add(dispatcher_vmo_destroy_count, 1);
   // Intentionally leave vmo_->user_id() set to our koid even though we're
   // dying and the koid will no longer map to a Dispatcher. koids are never
   // recycled, and it could be a useful breadcrumb.
 }

 void VmObjectDispatcher::OnZeroChild() { UpdateState(0, ZX_VMO_ZERO_CHILDREN); }

 void VmObjectDispatcher::OnOneChild() { UpdateState(ZX_VMO_ZERO_CHILDREN, 0); }

 void VmObjectDispatcher::get_name(char (&out_name)[ZX_MAX_NAME_LEN]) const {
   canary_.Assert();
   vmo_->get_name(out_name, ZX_MAX_NAME_LEN);
 }

 zx_status_t VmObjectDispatcher::set_name(const char* name, size_t len) {
   canary_.Assert();
   return vmo_->set_name(name, len);
 }

 void VmObjectDispatcher::on_zero_handles() {
   // Clear when handle count reaches zero rather in the destructor because we're retaining a
   // VmObject that might call back into |this| via VmObjectChildObserver when it's destroyed.
   vmo_->SetChildObserver(nullptr);
 }

 zx_status_t VmObjectDispatcher::Read(VmAspace* current_aspace, user_out_ptr<char> user_data,
                                      size_t length, uint64_t offset, size_t* out_actual) {
   canary_.Assert();

   return vmo_->ReadUser(current_aspace, user_data, offset, length, out_actual);
 }

 zx_status_t VmObjectDispatcher::ReadVector(VmAspace* current_aspace, user_out_iovec_t user_data,
                                            size_t length, uint64_t offset, size_t* out_actual) {
   canary_.Assert();

   return vmo_->ReadUserVector(current_aspace, user_data, offset, length, out_actual);
 }

 zx_status_t VmObjectDispatcher::WriteVector(VmAspace* current_aspace, user_in_iovec_t user_data,
                                             size_t length, uint64_t offset, size_t* out_actual) {
   canary_.Assert();

   return vmo_->WriteUserVector(current_aspace, user_data, offset, length, out_actual);
 }

 zx_status_t VmObjectDispatcher::Write(VmAspace* current_aspace, user_in_ptr<const char> user_data,
                                       size_t length, uint64_t offset, size_t* out_actual) {
   canary_.Assert();

   return vmo_->WriteUser(current_aspace, user_data, offset, length, out_actual);
 }

 zx_status_t VmObjectDispatcher::SetSize(uint64_t size) {
   canary_.Assert();

   ContentSizeManager::Operation op;
   Guard<Mutex> guard{content_size_mgr_.lock()};

   content_size_mgr_.BeginSetContentSizeLocked(size, &op, &guard);

   uint64_t size_aligned = ROUNDUP(size, PAGE_SIZE);
   // Check for overflow when rounding up.
   if (size_aligned < size) {
     op.AssertParentLockHeld();
     op.CancelLocked();
     return ZX_ERR_OUT_OF_RANGE;
   }

   zx_status_t status = vmo_->Resize(size_aligned);
   if (status != ZX_OK) {
     op.AssertParentLockHeld();
     op.CancelLocked();
     return status;
   }

   uint64_t remaining = size_aligned - size;
   if (remaining > 0) {
     // TODO(fxbug.dev/102757): Determine whether failure to ZeroRange here should undo this
     // operation.
     //
     // Dropping the lock here is fine, as an `Operation` only needs to be locked when initializing,
     // committing, or cancelling.
     guard.CallUnlocked([&] { vmo_->ZeroRange(size, remaining); });
   }

   op.AssertParentLockHeld();
   op.CommitLocked();
   return status;
 }

 zx_status_t VmObjectDispatcher::GetSize(uint64_t* size) {
   canary_.Assert();

   *size = vmo_->size();

   return ZX_OK;
 }

 zx_info_vmo_t VmoToInfoEntry(const VmObject* vmo, bool is_handle, zx_rights_t handle_rights) {
   zx_info_vmo_t entry = {};
   entry.koid = vmo->user_id();
   vmo->get_name(entry.name, sizeof(entry.name));
   entry.size_bytes = vmo->size();
   entry.parent_koid = vmo->parent_user_id();
   entry.num_children = vmo->num_user_children();
   entry.num_mappings = vmo->num_mappings();
   entry.share_count = vmo->share_count();
   entry.flags = (vmo->is_paged() ? ZX_INFO_VMO_TYPE_PAGED : ZX_INFO_VMO_TYPE_PHYSICAL) |
                 (vmo->is_resizable() ? ZX_INFO_VMO_RESIZABLE : 0) |
                 (vmo->is_discardable() ? ZX_INFO_VMO_DISCARDABLE : 0) |
                 (vmo->is_user_pager_backed() ? ZX_INFO_VMO_PAGER_BACKED : 0) |
                 (vmo->is_contiguous() ? ZX_INFO_VMO_CONTIGUOUS : 0);
   entry.committed_bytes = vmo->AttributedPages() * PAGE_SIZE;
   entry.cache_policy = vmo->GetMappingCachePolicy();
   if (is_handle) {
     entry.flags |= ZX_INFO_VMO_VIA_HANDLE;
     entry.handle_rights = handle_rights;
   } else {
     entry.flags |= ZX_INFO_VMO_VIA_MAPPING;
   }
   if (vmo->child_type() == VmObject::ChildType::kCowClone) {
     entry.flags |= ZX_INFO_VMO_IS_COW_CLONE;
   }
   entry.metadata_bytes = vmo->HeapAllocationBytes();
   // Only events that change committed pages are evictions at the moment.
   entry.committed_change_events = vmo->EvictionEventCount();
   return entry;
 }

 zx_info_vmo_t VmObjectDispatcher::GetVmoInfo(zx_rights_t rights) {
   zx_info_vmo_t info = VmoToInfoEntry(vmo().get(), true, rights);
   if (initial_mutability_ == InitialMutability::kImmutable) {
     info.flags |= ZX_INFO_VMO_IMMUTABLE;
   }
   return info;
 }

 zx_status_t VmObjectDispatcher::SetContentSize(uint64_t content_size) {
   canary_.Assert();

   ContentSizeManager::Operation op;
   Guard<Mutex> guard{content_size_mgr_.lock()};
   content_size_mgr_.BeginSetContentSizeLocked(content_size, &op, &guard);

   op.AssertParentLockHeld();
   op.CommitLocked();
   return ZX_OK;
 }

 uint64_t VmObjectDispatcher::GetContentSize() const {
   canary_.Assert();

   Guard<Mutex> guard{content_size_mgr_.lock()};
   return content_size_mgr_.content_size_locked();
 }

 zx_status_t VmObjectDispatcher::ExpandIfNecessary(uint64_t requested_vmo_size,
                                                   uint64_t* out_actual) {
   canary_.Assert();

   uint64_t current_vmo_size = vmo_->size();
   *out_actual = current_vmo_size;

   uint64_t required_vmo_size = ROUNDUP(requested_vmo_size, PAGE_SIZE);
   // Overflow when rounding up.
   if (required_vmo_size < requested_vmo_size) {
     return ZX_ERR_OUT_OF_RANGE;
   }

   if (required_vmo_size > current_vmo_size) {
     zx_status_t status = vmo_->Resize(required_vmo_size);
     if (status != ZX_OK) {
       // Resizing failed but the rest of the current VMO size can be used.
       return status;
     }

     *out_actual = required_vmo_size;
   }

   return ZX_OK;
 }

 zx_status_t VmObjectDispatcher::RangeOp(uint32_t op, uint64_t offset, uint64_t size,
                                         user_inout_ptr<void> buffer, size_t buffer_size,
                                         zx_rights_t rights) {
   canary_.Assert();

   LTRACEF("op %u offset %#" PRIx64 " size %#" PRIx64 " buffer %p buffer_size %zu rights %#x\n", op,
           offset, size, buffer.get(), buffer_size, rights);

   switch (op) {
     case ZX_VMO_OP_COMMIT: {
       if ((rights & ZX_RIGHT_WRITE) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       // TODO: handle partial commits
       auto status = vmo_->CommitRange(offset, size);
       return status;
     }
     case ZX_VMO_OP_DECOMMIT: {
       if ((rights & ZX_RIGHT_WRITE) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       // TODO: handle partial decommits
       auto status = vmo_->DecommitRange(offset, size);
       return status;
     }
     case ZX_VMO_OP_LOCK: {
       if ((rights & (ZX_RIGHT_READ | ZX_RIGHT_WRITE)) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }

       zx_vmo_lock_state_t lock_state = {};
       zx_status_t status = vmo_->LockRange(offset, size, &lock_state);
       if (status != ZX_OK) {
         return status;
       }
       // If an error is encountered from this point on, the lock operation MUST be reverted
       // before returning.

       if (buffer_size < sizeof(zx_vmo_lock_state_t)) {
         // Undo the lock before returning an error.
         vmo_->UnlockRange(offset, size);
         return ZX_ERR_INVALID_ARGS;
       }

       auto lock_state_out = buffer.reinterpret<zx_vmo_lock_state_t>();
       if ((status = lock_state_out.copy_to_user(lock_state)) != ZX_OK) {
         // Undo the lock before returning an error.
         vmo_->UnlockRange(offset, size);
         return status;
       }

       return status;
     }
     case ZX_VMO_OP_TRY_LOCK:
       if ((rights & (ZX_RIGHT_READ | ZX_RIGHT_WRITE)) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->TryLockRange(offset, size);
     case ZX_VMO_OP_UNLOCK:
       if ((rights & (ZX_RIGHT_READ | ZX_RIGHT_WRITE)) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->UnlockRange(offset, size);
     case ZX_VMO_OP_CACHE_SYNC:
       if ((rights & ZX_RIGHT_READ) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Sync);
     case ZX_VMO_OP_CACHE_INVALIDATE:
       if (!gBootOptions->enable_debugging_syscalls) {
         return ZX_ERR_NOT_SUPPORTED;
       }
       // A straight invalidate op requires the write right since
       // it may drop dirty cache lines, thus modifying the contents
       // of the VMO.
       if ((rights & ZX_RIGHT_WRITE) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Invalidate);
     case ZX_VMO_OP_CACHE_CLEAN:
       if ((rights & ZX_RIGHT_READ) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Clean);
     case ZX_VMO_OP_CACHE_CLEAN_INVALIDATE:
       if ((rights & ZX_RIGHT_READ) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->CacheOp(offset, size, VmObject::CacheOpType::CleanInvalidate);
     case ZX_VMO_OP_ZERO:
       if ((rights & ZX_RIGHT_WRITE) == 0) {
         return ZX_ERR_ACCESS_DENIED;
       }
       return vmo_->ZeroRange(offset, size);
     case ZX_VMO_OP_ALWAYS_NEED:
       return vmo_->HintRange(offset, size, VmObject::EvictionHint::AlwaysNeed);
     case ZX_VMO_OP_DONT_NEED:
       return vmo_->HintRange(offset, size, VmObject::EvictionHint::DontNeed);
     default:
       return ZX_ERR_INVALID_ARGS;
   }
 }

 zx_status_t VmObjectDispatcher::SetMappingCachePolicy(uint32_t cache_policy) {
   return vmo_->SetMappingCachePolicy(cache_policy);
 }

 zx_status_t VmObjectDispatcher::CreateChild(uint32_t options, uint64_t offset, uint64_t size,
                                             bool copy_name, fbl::RefPtr<VmObject>* child_vmo) {
   canary_.Assert();

   LTRACEF("options 0x%x offset %#" PRIx64 " size %#" PRIx64 "\n", options, offset, size);

   // Clones are not supported for discardable VMOs.
   if (vmo_->is_discardable()) {
     return ZX_ERR_NOT_SUPPORTED;
   }

   if (options & ZX_VMO_CHILD_SLICE) {
     // No other flags are valid for slices.
     options &= ~ZX_VMO_CHILD_SLICE;
     if (options) {
       return ZX_ERR_INVALID_ARGS;
     }
     return vmo_->CreateChildSlice(offset, size, copy_name, child_vmo);
   }

   // Check for mutually-exclusive child type flags.
   CloneType type;
   if (options & ZX_VMO_CHILD_SNAPSHOT) {
     options &= ~ZX_VMO_CHILD_SNAPSHOT;
     type = CloneType::Snapshot;
   } else if (options & ZX_VMO_CHILD_SNAPSHOT_AT_LEAST_ON_WRITE) {
     options &= ~ZX_VMO_CHILD_SNAPSHOT_AT_LEAST_ON_WRITE;
     if (vmo_->is_private_pager_copy_supported()) {
       type = CloneType::PrivatePagerCopy;
     } else {
       type = CloneType::Snapshot;
     }
   } else {
     return ZX_ERR_INVALID_ARGS;
   }

   Resizability resizable = Resizability::NonResizable;
   if (options & ZX_VMO_CHILD_RESIZABLE) {
     resizable = Resizability::Resizable;
     options &= ~ZX_VMO_CHILD_RESIZABLE;
   }

   if (options)
     return ZX_ERR_INVALID_ARGS;

   return vmo_->CreateClone(resizable, type, offset, size, copy_name, child_vmo);
 }
	// Copyright 2016 The Fuchsia Authors
	//
	// Use of this source code is governed by a MIT-style
	// license that can be found in the LICENSE file or at
	// https://opensource.org/licenses/MIT

	#include "object/vm_object_dispatcher.h"

	#include <assert.h>
	#include <inttypes.h>
	#include <lib/boot-options/boot-options.h>
	#include <lib/counters.h>
	#include <trace.h>
	#include <zircon/errors.h>
	#include <zircon/rights.h>

	#include <fbl/alloc_checker.h>
	#include <ktl/algorithm.h>
	#include <ktl/atomic.h>
	#include <ktl/optional.h>
	#include <vm/page_source.h>
	#include <vm/vm_aspace.h>
	#include <vm/vm_object.h>
	#include <vm/vm_object_paged.h>

	#include <ktl/enforce.h>

	#define LOCAL_TRACE 0

	KCOUNTER(dispatcher_vmo_create_count, "dispatcher.vmo.create")
	KCOUNTER(dispatcher_vmo_destroy_count, "dispatcher.vmo.destroy")

	zx_status_t VmObjectDispatcher::parse_create_syscall_flags(uint32_t flags, uint32_t* out_flags) {
	uint32_t res = 0;
	if (flags & ZX_VMO_RESIZABLE) {
	res \|= VmObjectPaged::kResizable;
	flags &= ~ZX_VMO_RESIZABLE;
	}
	if (flags & ZX_VMO_DISCARDABLE) {
	res \|= VmObjectPaged::kDiscardable;
	flags &= ~ZX_VMO_DISCARDABLE;
	}

	if (flags) {
	return ZX_ERR_INVALID_ARGS;
	}

	*out_flags = res;

	return ZX_OK;
	}

	zx_status_t VmObjectDispatcher::Create(fbl::RefPtr<VmObject> vmo, uint64_t content_size,
	zx_koid_t pager_koid, InitialMutability initial_mutability,
	KernelHandle<VmObjectDispatcher>* handle,
	zx_rights_t* rights) {
	fbl::AllocChecker ac;
	KernelHandle new_handle(fbl::AdoptRef(
	new (&ac) VmObjectDispatcher(ktl::move(vmo), content_size, pager_koid, initial_mutability)));
	if (!ac.check())
	return ZX_ERR_NO_MEMORY;

	new_handle.dispatcher()->vmo()->set_user_id(new_handle.dispatcher()->get_koid());
	*rights = default_rights();
	*handle = ktl::move(new_handle);
	return ZX_OK;
	}

	VmObjectDispatcher::VmObjectDispatcher(fbl::RefPtr<VmObject> vmo, uint64_t content_size,
	zx_koid_t pager_koid, InitialMutability initial_mutability)
	: SoloDispatcher(ZX_VMO_ZERO_CHILDREN),
	vmo_(ktl::move(vmo)),
	content_size_mgr_(content_size),
	pager_koid_(pager_koid),
	initial_mutability_(initial_mutability) {
	kcounter_add(dispatcher_vmo_create_count, 1);
	vmo_->SetChildObserver(this);
	}

	VmObjectDispatcher::~VmObjectDispatcher() {
	kcounter_add(dispatcher_vmo_destroy_count, 1);
	// Intentionally leave vmo_->user_id() set to our koid even though we're
	// dying and the koid will no longer map to a Dispatcher. koids are never
	// recycled, and it could be a useful breadcrumb.
	}

	void VmObjectDispatcher::OnZeroChild() { UpdateState(0, ZX_VMO_ZERO_CHILDREN); }

	void VmObjectDispatcher::OnOneChild() { UpdateState(ZX_VMO_ZERO_CHILDREN, 0); }

	void VmObjectDispatcher::get_name(char (&out_name)[ZX_MAX_NAME_LEN]) const {
	canary_.Assert();
	vmo_->get_name(out_name, ZX_MAX_NAME_LEN);
	}

	zx_status_t VmObjectDispatcher::set_name(const char* name, size_t len) {
	canary_.Assert();
	return vmo_->set_name(name, len);
	}

	void VmObjectDispatcher::on_zero_handles() {
	// Clear when handle count reaches zero rather in the destructor because we're retaining a
	// VmObject that might call back into \|this\| via VmObjectChildObserver when it's destroyed.
	vmo_->SetChildObserver(nullptr);
	}

	zx_status_t VmObjectDispatcher::Read(VmAspace* current_aspace, user_out_ptr<char> user_data,
	size_t length, uint64_t offset, size_t* out_actual) {
	canary_.Assert();

	return vmo_->ReadUser(current_aspace, user_data, offset, length, out_actual);
	}

	zx_status_t VmObjectDispatcher::ReadVector(VmAspace* current_aspace, user_out_iovec_t user_data,
	size_t length, uint64_t offset, size_t* out_actual) {
	canary_.Assert();

	return vmo_->ReadUserVector(current_aspace, user_data, offset, length, out_actual);
	}

	zx_status_t VmObjectDispatcher::WriteVector(VmAspace* current_aspace, user_in_iovec_t user_data,
	size_t length, uint64_t offset, size_t* out_actual) {
	canary_.Assert();

	return vmo_->WriteUserVector(current_aspace, user_data, offset, length, out_actual);
	}

	zx_status_t VmObjectDispatcher::Write(VmAspace* current_aspace, user_in_ptr<const char> user_data,
	size_t length, uint64_t offset, size_t* out_actual) {
	canary_.Assert();

	return vmo_->WriteUser(current_aspace, user_data, offset, length, out_actual);
	}

	zx_status_t VmObjectDispatcher::SetSize(uint64_t size) {
	canary_.Assert();

	ContentSizeManager::Operation op;
	Guard<Mutex> guard{content_size_mgr_.lock()};

	content_size_mgr_.BeginSetContentSizeLocked(size, &op, &guard);

	uint64_t size_aligned = ROUNDUP(size, PAGE_SIZE);
	// Check for overflow when rounding up.
	if (size_aligned < size) {
	op.AssertParentLockHeld();
	op.CancelLocked();
	return ZX_ERR_OUT_OF_RANGE;
	}

	zx_status_t status = vmo_->Resize(size_aligned);
	if (status != ZX_OK) {
	op.AssertParentLockHeld();
	op.CancelLocked();
	return status;
	}

	uint64_t remaining = size_aligned - size;
	if (remaining > 0) {
	// TODO(fxbug.dev/102757): Determine whether failure to ZeroRange here should undo this
	// operation.
	//
	// Dropping the lock here is fine, as an `Operation` only needs to be locked when initializing,
	// committing, or cancelling.
	guard.CallUnlocked([&] { vmo_->ZeroRange(size, remaining); });
	}

	op.AssertParentLockHeld();
	op.CommitLocked();
	return status;
	}

	zx_status_t VmObjectDispatcher::GetSize(uint64_t* size) {
	canary_.Assert();

	*size = vmo_->size();

	return ZX_OK;
	}

	zx_info_vmo_t VmoToInfoEntry(const VmObject* vmo, bool is_handle, zx_rights_t handle_rights) {
	zx_info_vmo_t entry = {};
	entry.koid = vmo->user_id();
	vmo->get_name(entry.name, sizeof(entry.name));
	entry.size_bytes = vmo->size();
	entry.parent_koid = vmo->parent_user_id();
	entry.num_children = vmo->num_user_children();
	entry.num_mappings = vmo->num_mappings();
	entry.share_count = vmo->share_count();
	entry.flags = (vmo->is_paged() ? ZX_INFO_VMO_TYPE_PAGED : ZX_INFO_VMO_TYPE_PHYSICAL) \|
	(vmo->is_resizable() ? ZX_INFO_VMO_RESIZABLE : 0) \|
	(vmo->is_discardable() ? ZX_INFO_VMO_DISCARDABLE : 0) \|
	(vmo->is_user_pager_backed() ? ZX_INFO_VMO_PAGER_BACKED : 0) \|
	(vmo->is_contiguous() ? ZX_INFO_VMO_CONTIGUOUS : 0);
	entry.committed_bytes = vmo->AttributedPages() * PAGE_SIZE;
	entry.cache_policy = vmo->GetMappingCachePolicy();
	if (is_handle) {
	entry.flags \|= ZX_INFO_VMO_VIA_HANDLE;
	entry.handle_rights = handle_rights;
	} else {
	entry.flags \|= ZX_INFO_VMO_VIA_MAPPING;
	}
	if (vmo->child_type() == VmObject::ChildType::kCowClone) {
	entry.flags \|= ZX_INFO_VMO_IS_COW_CLONE;
	}
	entry.metadata_bytes = vmo->HeapAllocationBytes();
	// Only events that change committed pages are evictions at the moment.
	entry.committed_change_events = vmo->EvictionEventCount();
	return entry;
	}

	zx_info_vmo_t VmObjectDispatcher::GetVmoInfo(zx_rights_t rights) {
	zx_info_vmo_t info = VmoToInfoEntry(vmo().get(), true, rights);
	if (initial_mutability_ == InitialMutability::kImmutable) {
	info.flags \|= ZX_INFO_VMO_IMMUTABLE;
	}
	return info;
	}

	zx_status_t VmObjectDispatcher::SetContentSize(uint64_t content_size) {
	canary_.Assert();

	ContentSizeManager::Operation op;
	Guard<Mutex> guard{content_size_mgr_.lock()};
	content_size_mgr_.BeginSetContentSizeLocked(content_size, &op, &guard);

	op.AssertParentLockHeld();
	op.CommitLocked();
	return ZX_OK;
	}

	uint64_t VmObjectDispatcher::GetContentSize() const {
	canary_.Assert();

	Guard<Mutex> guard{content_size_mgr_.lock()};
	return content_size_mgr_.content_size_locked();
	}

	zx_status_t VmObjectDispatcher::ExpandIfNecessary(uint64_t requested_vmo_size,
	uint64_t* out_actual) {
	canary_.Assert();

	uint64_t current_vmo_size = vmo_->size();
	*out_actual = current_vmo_size;

	uint64_t required_vmo_size = ROUNDUP(requested_vmo_size, PAGE_SIZE);
	// Overflow when rounding up.
	if (required_vmo_size < requested_vmo_size) {
	return ZX_ERR_OUT_OF_RANGE;
	}

	if (required_vmo_size > current_vmo_size) {
	zx_status_t status = vmo_->Resize(required_vmo_size);
	if (status != ZX_OK) {
	// Resizing failed but the rest of the current VMO size can be used.
	return status;
	}

	*out_actual = required_vmo_size;
	}

	return ZX_OK;
	}

	zx_status_t VmObjectDispatcher::RangeOp(uint32_t op, uint64_t offset, uint64_t size,
	user_inout_ptr<void> buffer, size_t buffer_size,
	zx_rights_t rights) {
	canary_.Assert();

	LTRACEF("op %u offset %#" PRIx64 " size %#" PRIx64 " buffer %p buffer_size %zu rights %#x\n", op,
	offset, size, buffer.get(), buffer_size, rights);

	switch (op) {
	case ZX_VMO_OP_COMMIT: {
	if ((rights & ZX_RIGHT_WRITE) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	// TODO: handle partial commits
	auto status = vmo_->CommitRange(offset, size);
	return status;
	}
	case ZX_VMO_OP_DECOMMIT: {
	if ((rights & ZX_RIGHT_WRITE) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	// TODO: handle partial decommits
	auto status = vmo_->DecommitRange(offset, size);
	return status;
	}
	case ZX_VMO_OP_LOCK: {
	if ((rights & (ZX_RIGHT_READ \| ZX_RIGHT_WRITE)) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}

	zx_vmo_lock_state_t lock_state = {};
	zx_status_t status = vmo_->LockRange(offset, size, &lock_state);
	if (status != ZX_OK) {
	return status;
	}
	// If an error is encountered from this point on, the lock operation MUST be reverted
	// before returning.

	if (buffer_size < sizeof(zx_vmo_lock_state_t)) {
	// Undo the lock before returning an error.
	vmo_->UnlockRange(offset, size);
	return ZX_ERR_INVALID_ARGS;
	}

	auto lock_state_out = buffer.reinterpret<zx_vmo_lock_state_t>();
	if ((status = lock_state_out.copy_to_user(lock_state)) != ZX_OK) {
	// Undo the lock before returning an error.
	vmo_->UnlockRange(offset, size);
	return status;
	}

	return status;
	}
	case ZX_VMO_OP_TRY_LOCK:
	if ((rights & (ZX_RIGHT_READ \| ZX_RIGHT_WRITE)) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->TryLockRange(offset, size);
	case ZX_VMO_OP_UNLOCK:
	if ((rights & (ZX_RIGHT_READ \| ZX_RIGHT_WRITE)) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->UnlockRange(offset, size);
	case ZX_VMO_OP_CACHE_SYNC:
	if ((rights & ZX_RIGHT_READ) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Sync);
	case ZX_VMO_OP_CACHE_INVALIDATE:
	if (!gBootOptions->enable_debugging_syscalls) {
	return ZX_ERR_NOT_SUPPORTED;
	}
	// A straight invalidate op requires the write right since
	// it may drop dirty cache lines, thus modifying the contents
	// of the VMO.
	if ((rights & ZX_RIGHT_WRITE) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Invalidate);
	case ZX_VMO_OP_CACHE_CLEAN:
	if ((rights & ZX_RIGHT_READ) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->CacheOp(offset, size, VmObject::CacheOpType::Clean);
	case ZX_VMO_OP_CACHE_CLEAN_INVALIDATE:
	if ((rights & ZX_RIGHT_READ) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->CacheOp(offset, size, VmObject::CacheOpType::CleanInvalidate);
	case ZX_VMO_OP_ZERO:
	if ((rights & ZX_RIGHT_WRITE) == 0) {
	return ZX_ERR_ACCESS_DENIED;
	}
	return vmo_->ZeroRange(offset, size);
	case ZX_VMO_OP_ALWAYS_NEED:
	return vmo_->HintRange(offset, size, VmObject::EvictionHint::AlwaysNeed);
	case ZX_VMO_OP_DONT_NEED:
	return vmo_->HintRange(offset, size, VmObject::EvictionHint::DontNeed);
	default:
	return ZX_ERR_INVALID_ARGS;
	}
	}

	zx_status_t VmObjectDispatcher::SetMappingCachePolicy(uint32_t cache_policy) {
	return vmo_->SetMappingCachePolicy(cache_policy);
	}

	zx_status_t VmObjectDispatcher::CreateChild(uint32_t options, uint64_t offset, uint64_t size,
	bool copy_name, fbl::RefPtr<VmObject>* child_vmo) {
	canary_.Assert();

	LTRACEF("options 0x%x offset %#" PRIx64 " size %#" PRIx64 "\n", options, offset, size);

	// Clones are not supported for discardable VMOs.
	if (vmo_->is_discardable()) {
	return ZX_ERR_NOT_SUPPORTED;
	}

	if (options & ZX_VMO_CHILD_SLICE) {
	// No other flags are valid for slices.
	options &= ~ZX_VMO_CHILD_SLICE;
	if (options) {
	return ZX_ERR_INVALID_ARGS;
	}
	return vmo_->CreateChildSlice(offset, size, copy_name, child_vmo);
	}

	// Check for mutually-exclusive child type flags.
	CloneType type;
	if (options & ZX_VMO_CHILD_SNAPSHOT) {
	options &= ~ZX_VMO_CHILD_SNAPSHOT;
	type = CloneType::Snapshot;
	} else if (options & ZX_VMO_CHILD_SNAPSHOT_AT_LEAST_ON_WRITE) {
	options &= ~ZX_VMO_CHILD_SNAPSHOT_AT_LEAST_ON_WRITE;
	if (vmo_->is_private_pager_copy_supported()) {
	type = CloneType::PrivatePagerCopy;
	} else {
	type = CloneType::Snapshot;
	}
	} else {
	return ZX_ERR_INVALID_ARGS;
	}

	Resizability resizable = Resizability::NonResizable;
	if (options & ZX_VMO_CHILD_RESIZABLE) {
	resizable = Resizability::Resizable;
	options &= ~ZX_VMO_CHILD_RESIZABLE;
	}

	if (options)
	return ZX_ERR_INVALID_ARGS;

	return vmo_->CreateClone(resizable, type, offset, size, copy_name, child_vmo);
	}