/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <mesosphere.hpp>
namespace ams::kern {
namespace {
ALWAYS_INLINE bool ReadFromUser(u32 *out, KProcessAddress address) {
return UserspaceAccess::CopyMemoryFromUserSize32Bit(out, GetVoidPointer(address));
}
ALWAYS_INLINE bool WriteToUser(KProcessAddress address, const u32 *p) {
return UserspaceAccess::CopyMemoryToUserSize32Bit(GetVoidPointer(address), p);
}
ALWAYS_INLINE bool UpdateLockAtomic(u32 *out, KProcessAddress address, u32 if_zero, u32 new_orr_mask) {
return UserspaceAccess::UpdateLockAtomic(out, GetPointer<u32>(address), if_zero, new_orr_mask);
}
}
Result KConditionVariable::SignalToAddress(KProcessAddress addr) {
KThread *owner_thread = std::addressof(GetCurrentThread());
/* Signal the address. */
{
KScopedSchedulerLock sl;
/* Remove waiter thread. */
s32 num_waiters;
KThread *next_owner_thread = owner_thread->RemoveWaiterByKey(std::addressof(num_waiters), addr);
/* Determine the next tag. */
u32 next_value = 0;
if (next_owner_thread) {
next_value = next_owner_thread->GetAddressKeyValue();
if (num_waiters > 1) {
next_value |= ams::svc::HandleWaitMask;
}
next_owner_thread->SetSyncedObject(nullptr, ResultSuccess());
next_owner_thread->Wakeup();
}
/* Write the value to userspace. */
if (!WriteToUser(addr, std::addressof(next_value))) {
if (next_owner_thread) {
next_owner_thread->SetSyncedObject(nullptr, svc::ResultInvalidCurrentMemory());
}
return svc::ResultInvalidCurrentMemory();
}
}
return ResultSuccess();
}
Result KConditionVariable::WaitForAddress(ams::svc::Handle handle, KProcessAddress addr, u32 value) {
KThread *cur_thread = std::addressof(GetCurrentThread());
/* Wait for the address. */
{
KScopedAutoObject<KThread> owner_thread;
MESOSPHERE_ASSERT(owner_thread.IsNull());
{
KScopedSchedulerLock sl;
cur_thread->SetSyncedObject(nullptr, ResultSuccess());
/* Check if the thread should terminate. */
R_UNLESS(!cur_thread->IsTerminationRequested(), svc::ResultTerminationRequested());
{
/* Read the tag from userspace. */
u32 test_tag;
R_UNLESS(ReadFromUser(std::addressof(test_tag), addr), svc::ResultInvalidCurrentMemory());
/* If the tag isn't the handle (with wait mask), we're done. */
R_SUCCEED_IF(test_tag != (handle | ams::svc::HandleWaitMask));
/* Get the lock owner thread. */
owner_thread = GetCurrentProcess().GetHandleTable().GetObjectWithoutPseudoHandle<KThread>(handle);
R_UNLESS(owner_thread.IsNotNull(), svc::ResultInvalidHandle());
/* Update the lock. */
cur_thread->SetAddressKey(addr, value);
owner_thread->AddWaiter(cur_thread);
cur_thread->SetState(KThread::ThreadState_Waiting);
}
}
MESOSPHERE_ASSERT(owner_thread.IsNotNull());
/* Remove the thread as a waiter from the lock owner. */
{
KScopedSchedulerLock sl;
if (KThread *mutex_owner = cur_thread->GetLockOwner(); mutex_owner != nullptr) {
mutex_owner->RemoveWaiter(cur_thread);
}
}
}
/* Get the wait result. */
KSynchronizationObject *dummy;
return cur_thread->GetWaitResult(std::addressof(dummy));
}
void KConditionVariable::SignalImpl(KThread *thread) {
/* Check pre-conditions. */
MESOSPHERE_ASSERT(KScheduler::IsSchedulerLockedByCurrentThread());
/* Update the tag. */
KProcessAddress address = thread->GetAddressKey();
u32 own_tag = thread->GetAddressKeyValue();
u32 prev_tag;
bool can_access;
{
KScopedInterruptDisable di;
can_access = cpu::CanAccessAtomic(address);
if (AMS_LIKELY(can_access)) {
can_access = UpdateLockAtomic(std::addressof(prev_tag), address, own_tag, ams::svc::HandleWaitMask);
}
}
if (AMS_LIKELY(can_access)) {
if (prev_tag == ams::svc::InvalidHandle) {
/* If nobody held the lock previously, we're all good. */
thread->SetSyncedObject(nullptr, ResultSuccess());
thread->Wakeup();
} else {
/* Get the previous owner. */
KThread *owner_thread = GetCurrentProcess().GetHandleTable().GetObjectWithoutPseudoHandle<KThread>(static_cast<ams::svc::Handle>(prev_tag & ~ams::svc::HandleWaitMask))
.ReleasePointerUnsafe();
if (AMS_LIKELY(owner_thread != nullptr)) {
/* Add the thread as a waiter on the owner. */
owner_thread->AddWaiter(thread);
owner_thread->Close();
} else {
/* The lock was tagged with a thread that doesn't exist. */
thread->SetSyncedObject(nullptr, svc::ResultInvalidState());
thread->Wakeup();
}
}
} else {
/* If the address wasn't accessible, note so. */
thread->SetSyncedObject(nullptr, svc::ResultInvalidCurrentMemory());
thread->Wakeup();
}
}
void KConditionVariable::Signal(uintptr_t cv_key, s32 count) {
/* Perform signaling. */
int num_waiters = 0;
{
KScopedSchedulerLock sl;
auto it = m_tree.nfind_key({ cv_key, -1 });
while ((it != m_tree.end()) && (count <= 0 || num_waiters < count) && (it->GetConditionVariableKey() == cv_key)) {
KThread *target_thread = std::addressof(*it);
this->SignalImpl(target_thread);
it = m_tree.erase(it);
target_thread->ClearConditionVariable();
++num_waiters;
}
/* If we have no waiters, clear the has waiter flag. */
if (it == m_tree.end() || it->GetConditionVariableKey() != cv_key) {
const u32 has_waiter_flag = 0;
WriteToUser(cv_key, std::addressof(has_waiter_flag));
}
}
}
Result KConditionVariable::Wait(KProcessAddress addr, uintptr_t key, u32 value, s64 timeout) {
/* Prepare to wait. */
KThread *cur_thread = GetCurrentThreadPointer();
KHardwareTimer *timer;
{
KScopedSchedulerLockAndSleep slp(std::addressof(timer), cur_thread, timeout);
/* Set the synced object. */
cur_thread->SetSyncedObject(nullptr, ams::svc::ResultTimedOut());
/* Check that the thread isn't terminating. */
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
return svc::ResultTerminationRequested();
}
/* Update the value and process for the next owner. */
{
/* Remove waiter thread. */
s32 num_waiters;
KThread *next_owner_thread = cur_thread->RemoveWaiterByKey(std::addressof(num_waiters), GetInteger(addr));
/* Update for the next owner thread. */
u32 next_value = 0;
if (next_owner_thread != nullptr) {
/* Get the next tag value. */
next_value = next_owner_thread->GetAddressKeyValue();
if (num_waiters > 1) {
next_value |= ams::svc::HandleWaitMask;
}
/* Wake up the next owner. */
next_owner_thread->SetSyncedObject(nullptr, ResultSuccess());
next_owner_thread->Wakeup();
}
/* Write to the cv key. */
{
const u32 has_waiter_flag = 1;
WriteToUser(key, std::addressof(has_waiter_flag));
cpu::DataMemoryBarrier();
}
/* Write the value to userspace. */
if (!WriteToUser(addr, std::addressof(next_value))) {
slp.CancelSleep();
return svc::ResultInvalidCurrentMemory();
}
}
/* Update condition variable tracking. */
{
cur_thread->SetConditionVariable(std::addressof(m_tree), addr, key, value);
m_tree.insert(*cur_thread);
}
/* If the timeout is non-zero, set the thread as waiting. */
if (timeout != 0) {
cur_thread->SetState(KThread::ThreadState_Waiting);
}
}
/* Remove from the condition variable. */
{
KScopedSchedulerLock sl;
if (KThread *owner = cur_thread->GetLockOwner(); owner != nullptr) {
owner->RemoveWaiter(cur_thread);
}
if (cur_thread->IsWaitingForConditionVariable()) {
m_tree.erase(m_tree.iterator_to(*cur_thread));
cur_thread->ClearConditionVariable();
}
}
/* Cancel the timer wait. */
if (timer != nullptr) {
timer->CancelTask(cur_thread);
}
/* Get the result. */
KSynchronizationObject *dummy;
return cur_thread->GetWaitResult(std::addressof(dummy));
}
}