5e7605fad2
The idle thread is now actually run when the system is idle because it truly goes idle. The idle thread is made power efficient by using the hlt instruction rather than a busy loop. The new futex(2) system call is used to implement fast user-space mutexes, condition variables, and semaphores. The same backend and design is used as kutexes for truly sleeping kernel mutexes and condition variables. The new exit_thread(2) flag EXIT_THREAD_FUTEX_WAKE wakes a futex. Sleeping on clocks in the kernel now uses timers for true sleep. The interrupt worker thread now truly sleeps when idle. Kernel threads are now named. This is a compatible ABI change.
76 lines
2.2 KiB
C++
76 lines
2.2 KiB
C++
/*
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* Copyright (c) 2012, 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* interlock.cpp
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* Functions that perform non-atomic operations in an atomic manner.
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*/
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#include <sortix/kernel/interlock.h>
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#include <sortix/kernel/kernel.h>
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namespace Sortix {
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// TODO: This is likely not the most optimal way to perform these operations.
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// TODO: Just discard this whole thing in favor of __atomic_?
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ilret_t InterlockedModify(unsigned long* ptr,
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ilockfunc f,
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unsigned long user)
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{
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unsigned long old_value, new_value;
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// TODO: Migrate to __atomic.
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do
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{
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old_value = *((volatile unsigned long*) ptr); /* TODO: Need volatile? */
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new_value = f(old_value, user);
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} while ( !__sync_bool_compare_and_swap(ptr, old_value, new_value) );
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ilret_t ret;
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ret.o = old_value;
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ret.n = new_value;
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return ret;
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}
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static unsigned long AddFunction(unsigned long val, unsigned long arg)
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{
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return val + arg;
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}
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static unsigned long SubFunction(unsigned long val, unsigned long arg)
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{
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return val - arg;
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}
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ilret_t InterlockedIncrement(unsigned long* ptr)
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{
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return InterlockedModify(ptr, AddFunction, 1);
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}
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ilret_t InterlockedDecrement(unsigned long* ptr)
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{
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return InterlockedModify(ptr, SubFunction, 1);
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}
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ilret_t InterlockedAdd(unsigned long* ptr, unsigned long arg)
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{
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return InterlockedModify(ptr, AddFunction, arg);
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}
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ilret_t InterlockedSub(unsigned long* ptr, unsigned long arg)
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{
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return InterlockedModify(ptr, SubFunction, arg);
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}
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} // namespace Sortix
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