kernel: fix unbounded stack usage in atomics
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9c96d40586
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9efd95cda5
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@ -35,24 +35,30 @@ bool DecrementIfLessThan(Core::System& system, s32* out, KProcessAddress address
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// TODO(bunnei): We should call CanAccessAtomic(..) here.
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// Load the value from the address.
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const s32 current_value =
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static_cast<s32>(monitor.ExclusiveRead32(current_core, GetInteger(address)));
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s32 current_value{};
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// Compare it to the desired one.
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if (current_value < value) {
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// If less than, we want to try to decrement.
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const s32 decrement_value = current_value - 1;
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while (true) {
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// Load the value from the address.
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current_value =
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static_cast<s32>(monitor.ExclusiveRead32(current_core, GetInteger(address)));
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// Compare it to the desired one.
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if (current_value < value) {
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// If less than, we want to try to decrement.
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const s32 decrement_value = current_value - 1;
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// Decrement and try to store.
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if (monitor.ExclusiveWrite32(current_core, GetInteger(address),
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static_cast<u32>(decrement_value))) {
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break;
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}
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// Decrement and try to store.
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if (!monitor.ExclusiveWrite32(current_core, GetInteger(address),
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static_cast<u32>(decrement_value))) {
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// If we failed to store, try again.
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DecrementIfLessThan(system, out, address, value);
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} else {
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// Otherwise, clear our exclusive hold and finish
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monitor.ClearExclusive(current_core);
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break;
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}
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} else {
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// Otherwise, clear our exclusive hold and finish
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monitor.ClearExclusive(current_core);
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}
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// We're done.
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@ -70,23 +76,29 @@ bool UpdateIfEqual(Core::System& system, s32* out, KProcessAddress address, s32
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// TODO(bunnei): We should call CanAccessAtomic(..) here.
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s32 current_value{};
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// Load the value from the address.
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const s32 current_value =
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static_cast<s32>(monitor.ExclusiveRead32(current_core, GetInteger(address)));
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while (true) {
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current_value =
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static_cast<s32>(monitor.ExclusiveRead32(current_core, GetInteger(address)));
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// Compare it to the desired one.
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if (current_value == value) {
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// If equal, we want to try to write the new value.
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// Compare it to the desired one.
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if (current_value == value) {
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// If equal, we want to try to write the new value.
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// Try to store.
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if (monitor.ExclusiveWrite32(current_core, GetInteger(address),
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static_cast<u32>(new_value))) {
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break;
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}
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// Try to store.
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if (!monitor.ExclusiveWrite32(current_core, GetInteger(address),
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static_cast<u32>(new_value))) {
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// If we failed to store, try again.
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UpdateIfEqual(system, out, address, value, new_value);
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} else {
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// Otherwise, clear our exclusive hold and finish.
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monitor.ClearExclusive(current_core);
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break;
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}
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} else {
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// Otherwise, clear our exclusive hold and finish.
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monitor.ClearExclusive(current_core);
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}
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// We're done.
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@ -33,21 +33,26 @@ bool UpdateLockAtomic(Core::System& system, u32* out, KProcessAddress address, u
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auto& monitor = system.Monitor();
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const auto current_core = system.Kernel().CurrentPhysicalCoreIndex();
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// Load the value from the address.
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const auto expected = monitor.ExclusiveRead32(current_core, GetInteger(address));
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u32 expected{};
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// Orr in the new mask.
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u32 value = expected | new_orr_mask;
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while (true) {
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// Load the value from the address.
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expected = monitor.ExclusiveRead32(current_core, GetInteger(address));
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// If the value is zero, use the if_zero value, otherwise use the newly orr'd value.
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if (!expected) {
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value = if_zero;
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}
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// Orr in the new mask.
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u32 value = expected | new_orr_mask;
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// If the value is zero, use the if_zero value, otherwise use the newly orr'd value.
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if (!expected) {
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value = if_zero;
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}
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// Try to store.
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if (monitor.ExclusiveWrite32(current_core, GetInteger(address), value)) {
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break;
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}
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// Try to store.
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if (!monitor.ExclusiveWrite32(current_core, GetInteger(address), value)) {
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// If we failed to store, try again.
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return UpdateLockAtomic(system, out, address, if_zero, new_orr_mask);
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}
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// We're done.
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