matos/core/thread.h

#pragma once

struct thread;
#include "cpu_context.h"
#include "mem.h"
#include "process.h"
#include "wait.h"

#define THREAD_NAME_MAX_LENGTH 32
#define THREAD_DEFAULT_STACK_SIZE PAGE_SIZE


typedef enum {
    RUNNING,
    READY,
    SLEEPING,
    WAITING,
    EXITING
} thread_state;

typedef unsigned long int thread_id_t;

struct thread {
    char name[THREAD_NAME_MAX_LENGTH];
    thread_id_t tid;
    struct cpu_state *cpuState;
    thread_state state;
    vaddr_t stackAddr;
    size_t stackSize;

    unsigned long jiffiesSleeping;
    int sleepHaveTimeouted;

    struct thread *next, *prev;
    struct thread *timeNext, *timePrev;
    // For User thread only
    struct thread *nextInProcess, *prevInProcess;
    struct process *process;
    struct wait_queue *wqExit; // This will be signaled at thread exit (user only)

  /**
   * Address space currently "squatted" by the thread, or used to be
   * active when the thread was interrupted/preempted. This is the MMU
   * configuration expected before the cpu_state of the thread is
   * restored on CPU.
   *   - For kernel threads: should normally be NULL, meaning that the
   *     thread will squat the current mm_context currently set in the
   *     MMU. Might be NON NULL when a kernel thread squats a given
   *     process to manipulate its address space.
   *   - For user threads: should normally be NULL. More precisely:
   *       - in user mode: the thread->process.mm_context is ALWAYS
   *         set on MMU. squatted_mm_context is ALWAYS NULL in this
   *         situation, meaning that the thread in user mode uses its
   *         process-space as expected
   *       - in kernel mode: NULL means that we keep on using the
   *         mm_context currently set on MMU, which might be the
   *         mm_context of another process. This is natural since a
   *         thread in kernel mode normally only uses data in kernel
   *         space. BTW, this limits the number of TLB flushes. However,
   *         there are exceptions where this squatted_mm_context will
   *         NOT be NULL. One is the copy_from/to_user API, which can
   *         force the effective mm_context so that the MMU will be
   *         (re)configured upon every context to the thread to match
   *         the squatted_mm_context. Another exception is when a parent
   *         thread creates the address space of a child process, in
   *         which case the parent thread might temporarilly decide to
   *         switch to the child's process space.
   *
   * This is the SOS/matos implementation of the Linux "Lazy TLB" and
   * address-space loaning.
   */
  struct mmu_context *squattedContext;

};

int threadSetup(vaddr_t mainStack, size_t mainStackSize);
void threadExit();

struct thread *threadCreate(const char *name, cpu_kstate_function_arg1_t func, void *args);
struct thread *threadCreateUser(const char *name, struct process *proc, uaddr_t startPc,
                                uint32_t arg1, uint32_t arg2, uaddr_t startSP);
void threadDelete(struct thread *thread);

struct thread *threadSelectNext();
struct cpu_state *threadSwitch(struct cpu_state *prevCpu);

int threadYield();
int threadWait(struct thread *current, struct thread *next, unsigned long msec);
int threadUnsched(struct thread *th);
int threadMsleep(unsigned long msec);
int threadUsleep(unsigned long usec);
int threadOnJieffiesTick();
struct thread *getCurrentThread();
int threadAddThread(struct thread *th);
int threadChangeCurrentContext(struct mmu_context *ctx);
int threadCount();
thread_id_t threadGetId(struct thread *th);