112 lines
4.3 KiB
C
112 lines
4.3 KiB
C
/*
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* task.h – Cooperative multitasking interface.
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*
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* Provides process control blocks (PCBs), a round-robin scheduler,
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* and voluntary yield/exit primitives. Context switching is performed
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* by the assembly routine in context_switch.S.
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*/
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#ifndef TASK_H
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#define TASK_H
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#include "kernel_types.h"
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#include "boot_info.h"
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/* ================================================================
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* Configuration
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* ================================================================ */
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#define TASK_MAX 32 /* max concurrent tasks */
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#define TASK_STACK_PAGES 8 /* 32 KB stack per task */
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#define TASK_STACK_SIZE (TASK_STACK_PAGES * 4096)
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#define TASK_NAME_LEN 32 /* max name length (CHAR16) */
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/* ================================================================
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* Task states
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* ================================================================ */
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typedef enum {
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TASK_STATE_FREE = 0, /* PCB slot is unused */
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TASK_STATE_READY, /* runnable, waiting to be scheduled */
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TASK_STATE_RUNNING, /* currently executing on the CPU */
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TASK_STATE_TERMINATED /* finished; slot will be recycled */
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} TaskState;
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/*
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* Logical privilege level for a task.
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*
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* Higher numeric values are more privileged:
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* USER (0) – least privileged
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* DRIVER (1) – mid-level, can talk to hardware-facing subsystems
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* KERNEL (2) – most privileged, core kernel and management threads
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*
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* All tasks still execute in ring 0 today; this is a software
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* hierarchy used for access control decisions and future paging work.
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*/
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typedef enum {
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TASK_PRIV_USER = 0,
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TASK_PRIV_DRIVER = 1,
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TASK_PRIV_KERNEL = 2,
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} TaskPrivilege;
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/* ================================================================
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* Task entry function
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* ================================================================ */
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/* Signature for the function a new task begins executing. */
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typedef void (*TaskEntryFn)(void *arg);
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/* ================================================================
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* Process Control Block (PCB)
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* ================================================================ */
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typedef struct Task {
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UINT32 pid; /* unique process ID */
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TaskState state; /* current lifecycle state */
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TaskPrivilege privilege; /* logical privilege level */
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CHAR16 name[TASK_NAME_LEN]; /* human-readable label */
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/* Context switch state */
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UINT64 saved_rsp; /* RSP saved by context_switch() */
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UINT64 stack_base; /* base phys addr of stack alloc */
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UINTN stack_pages; /* stack size in pages */
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/* Entry point */
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TaskEntryFn entry; /* function pointer */
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void *arg; /* argument passed to entry() */
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/* Scheduling metadata */
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UINTN switches; /* number of times scheduled */
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} Task;
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/* ================================================================
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* Public API
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* ================================================================ */
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void task_init(BootInfo *Boot); /* initialise scheduler */
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/* Spawn a new task with a specific privilege level. */
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Task *task_create_with_priv(const CHAR16 *name,
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TaskEntryFn entry,
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void *arg,
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TaskPrivilege privilege);
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/* Backwards-compatible helper: creates a kernel-privileged task. */
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Task *task_create(const CHAR16 *name,
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TaskEntryFn entry, void *arg);
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void task_yield(void); /* voluntarily give up the CPU */
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void task_exit(void); /* terminate the current task */
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Task *task_current(void); /* return the running task's PCB */
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TaskPrivilege task_get_privilege(Task *t);
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void task_set_privilege(Task *t, TaskPrivilege privilege);
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UINTN task_count(void); /* number of non-FREE tasks */
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void task_print_list(BootInfo *Boot); /* print task table (for `ps`) */
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/* Block the current task until the target task has finished. */
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void task_wait(Task *t);
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/* Assembly context switch (defined in context_switch.S). */
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extern void context_switch(UINT64 *old_rsp, UINT64 new_rsp);
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#endif /* TASK_H */
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