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Atmosphere/libraries/libmesosphere/source/kern_k_address_arbiter.cpp
SciresM 96f95b9f95
Integrate new result macros. (#1780)
* result: try out some experimental shenanigans

* result: sketch out some more shenanigans

* result: see what it looks like to convert kernel to use result conds instead of guards

* make rest of kernel use experimental new macro-ing
2022-02-14 14:45:32 -08:00

278 lines
10 KiB
C++

/*
* Copyright (c) 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(s32 *out, KProcessAddress address) {
return UserspaceAccess::CopyMemoryFromUserSize32Bit(out, GetVoidPointer(address));
}
ALWAYS_INLINE bool DecrementIfLessThan(s32 *out, KProcessAddress address, s32 value) {
KScopedInterruptDisable di;
if (!cpu::CanAccessAtomic(address)) {
return false;
}
return UserspaceAccess::DecrementIfLessThanAtomic(out, GetPointer<s32>(address), value);
}
ALWAYS_INLINE bool UpdateIfEqual(s32 *out, KProcessAddress address, s32 value, s32 new_value) {
KScopedInterruptDisable di;
if (!cpu::CanAccessAtomic(address)) {
return false;
}
return UserspaceAccess::UpdateIfEqualAtomic(out, GetPointer<s32>(address), value, new_value);
}
class ThreadQueueImplForKAddressArbiter final : public KThreadQueue {
private:
KAddressArbiter::ThreadTree *m_tree;
public:
constexpr ThreadQueueImplForKAddressArbiter(KAddressArbiter::ThreadTree *t) : KThreadQueue(), m_tree(t) { /* ... */ }
virtual void CancelWait(KThread *waiting_thread, Result wait_result, bool cancel_timer_task) override {
/* If the thread is waiting on an address arbiter, remove it from the tree. */
if (waiting_thread->IsWaitingForAddressArbiter()) {
m_tree->erase(m_tree->iterator_to(*waiting_thread));
waiting_thread->ClearAddressArbiter();
}
/* Invoke the base cancel wait handler. */
KThreadQueue::CancelWait(waiting_thread, wait_result, cancel_timer_task);
}
};
}
Result KAddressArbiter::Signal(uintptr_t addr, s32 count) {
/* Perform signaling. */
s32 num_waiters = 0;
{
KScopedSchedulerLock sl;
auto it = m_tree.nfind_key({ addr, -1 });
while ((it != m_tree.end()) && (count <= 0 || num_waiters < count) && (it->GetAddressArbiterKey() == addr)) {
/* End the thread's wait. */
KThread *target_thread = std::addressof(*it);
target_thread->EndWait(ResultSuccess());
MESOSPHERE_ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->ClearAddressArbiter();
it = m_tree.erase(it);
++num_waiters;
}
}
R_SUCCEED();
}
Result KAddressArbiter::SignalAndIncrementIfEqual(uintptr_t addr, s32 value, s32 count) {
/* Perform signaling. */
s32 num_waiters = 0;
{
KScopedSchedulerLock sl;
/* Check the userspace value. */
s32 user_value;
R_UNLESS(UpdateIfEqual(std::addressof(user_value), addr, value, value + 1), svc::ResultInvalidCurrentMemory());
R_UNLESS(user_value == value, svc::ResultInvalidState());
auto it = m_tree.nfind_key({ addr, -1 });
while ((it != m_tree.end()) && (count <= 0 || num_waiters < count) && (it->GetAddressArbiterKey() == addr)) {
/* End the thread's wait. */
KThread *target_thread = std::addressof(*it);
target_thread->EndWait(ResultSuccess());
MESOSPHERE_ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->ClearAddressArbiter();
it = m_tree.erase(it);
++num_waiters;
}
}
R_SUCCEED();
}
Result KAddressArbiter::SignalAndModifyByWaitingCountIfEqual(uintptr_t addr, s32 value, s32 count) {
/* Perform signaling. */
s32 num_waiters = 0;
{
KScopedSchedulerLock sl;
auto it = m_tree.nfind_key({ addr, -1 });
/* Determine the updated value. */
s32 new_value;
if (count <= 0) {
if ((it != m_tree.end()) && (it->GetAddressArbiterKey() == addr)) {
new_value = value - 2;
} else {
new_value = value + 1;
}
} else {
if ((it != m_tree.end()) && (it->GetAddressArbiterKey() == addr)) {
auto tmp_it = it;
s32 tmp_num_waiters = 0;
while ((++tmp_it != m_tree.end()) && (tmp_it->GetAddressArbiterKey() == addr)) {
if ((tmp_num_waiters++) >= count) {
break;
}
}
if (tmp_num_waiters < count) {
new_value = value - 1;
} else {
new_value = value;
}
} else {
new_value = value + 1;
}
}
/* Check the userspace value. */
s32 user_value;
bool succeeded;
if (value != new_value) {
succeeded = UpdateIfEqual(std::addressof(user_value), addr, value, new_value);
} else {
succeeded = ReadFromUser(std::addressof(user_value), addr);
}
R_UNLESS(succeeded, svc::ResultInvalidCurrentMemory());
R_UNLESS(user_value == value, svc::ResultInvalidState());
while ((it != m_tree.end()) && (count <= 0 || num_waiters < count) && (it->GetAddressArbiterKey() == addr)) {
/* End the thread's wait. */
KThread *target_thread = std::addressof(*it);
target_thread->EndWait(ResultSuccess());
MESOSPHERE_ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->ClearAddressArbiter();
it = m_tree.erase(it);
++num_waiters;
}
}
R_SUCCEED();
}
Result KAddressArbiter::WaitIfLessThan(uintptr_t addr, s32 value, bool decrement, s64 timeout) {
/* Prepare to wait. */
KThread *cur_thread = GetCurrentThreadPointer();
KHardwareTimer *timer;
ThreadQueueImplForKAddressArbiter wait_queue(std::addressof(m_tree));
{
KScopedSchedulerLockAndSleep slp(std::addressof(timer), cur_thread, timeout);
/* Check that the thread isn't terminating. */
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
R_THROW(svc::ResultTerminationRequested());
}
/* Read the value from userspace. */
s32 user_value;
bool succeeded;
if (decrement) {
succeeded = DecrementIfLessThan(std::addressof(user_value), addr, value);
} else {
succeeded = ReadFromUser(std::addressof(user_value), addr);
}
if (!succeeded) {
slp.CancelSleep();
R_THROW(svc::ResultInvalidCurrentMemory());
}
/* Check that the value is less than the specified one. */
if (user_value >= value) {
slp.CancelSleep();
R_THROW(svc::ResultInvalidState());
}
/* Check that the timeout is non-zero. */
if (timeout == 0) {
slp.CancelSleep();
R_THROW(svc::ResultTimedOut());
}
/* Set the arbiter. */
cur_thread->SetAddressArbiter(std::addressof(m_tree), addr);
m_tree.insert(*cur_thread);
/* Wait for the thread to finish. */
wait_queue.SetHardwareTimer(timer);
cur_thread->BeginWait(std::addressof(wait_queue));
}
/* Get the wait result. */
R_RETURN(cur_thread->GetWaitResult());
}
Result KAddressArbiter::WaitIfEqual(uintptr_t addr, s32 value, s64 timeout) {
/* Prepare to wait. */
KThread *cur_thread = GetCurrentThreadPointer();
KHardwareTimer *timer;
ThreadQueueImplForKAddressArbiter wait_queue(std::addressof(m_tree));
{
KScopedSchedulerLockAndSleep slp(std::addressof(timer), cur_thread, timeout);
/* Check that the thread isn't terminating. */
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
R_THROW(svc::ResultTerminationRequested());
}
/* Read the value from userspace. */
s32 user_value;
if (!ReadFromUser(std::addressof(user_value), addr)) {
slp.CancelSleep();
R_THROW(svc::ResultInvalidCurrentMemory());
}
/* Check that the value is equal. */
if (value != user_value) {
slp.CancelSleep();
R_THROW(svc::ResultInvalidState());
}
/* Check that the timeout is non-zero. */
if (timeout == 0) {
slp.CancelSleep();
R_THROW(svc::ResultTimedOut());
}
/* Set the arbiter. */
cur_thread->SetAddressArbiter(std::addressof(m_tree), addr);
m_tree.insert(*cur_thread);
/* Wait for the thread to finish. */
wait_queue.SetHardwareTimer(timer);
cur_thread->BeginWait(std::addressof(wait_queue));
}
/* Get the wait result. */
R_RETURN(cur_thread->GetWaitResult());
}
}