#include <stddef.h>
#include "debug.h"
#include "interrupt.h"
+#include "intr-stubs.h"
#include "lib.h"
#include "mmu.h"
#include "palloc.h"
#include "random.h"
+#include "switch.h"
uint32_t thread_stack_ofs = offsetof (struct thread, stack);
static struct list run_queue;
-struct thread *thread_switch (struct thread *cur, struct thread *next);
-
void
thread_init (void)
{
list_init (&run_queue);
}
+struct thread_root_frame
+ {
+ void *eip; /* Return address. */
+ void (*function) (void *); /* Function to call. */
+ void *aux; /* Auxiliary data for function. */
+ };
+
static void
thread_root (void (*function) (void *aux), void *aux)
{
thread_exit ();
}
+static struct thread *
+new_thread (const char *name)
+{
+ struct thread *t;
+
+ ASSERT (name != NULL);
+
+ t = palloc_get (PAL_ZERO);
+ if (t != NULL)
+ {
+ strlcpy (t->name, name, sizeof t->name);
+ t->stack = (uint8_t *) t + PGSIZE;
+ t->status = THREAD_BLOCKED;
+ }
+
+ return t;
+}
+
+static void *
+alloc_frame (struct thread *t, size_t size)
+{
+ ASSERT (size % sizeof (uint32_t) == 0);
+
+ t->stack -= size;
+ return t->stack;
+}
+
struct thread *
thread_create (const char *name, void (*function) (void *aux), void *aux)
{
struct thread *t;
+ struct thread_root_frame *rf;
+ struct switch_entry_frame *ef;
+ struct switch_threads_frame *sf;
- ASSERT (name != NULL);
ASSERT (function != NULL);
- t = palloc_get (0);
- if (t == NULL)
- return NULL;
+ t = new_thread (name);
- memset (t, 0, NBPG);
- strlcpy (t->name, name, sizeof t->name);
+ /* Stack frame for thread_root(). */
+ rf = alloc_frame (t, sizeof *rf);
+ rf->eip = NULL;
+ rf->function = function;
+ rf->aux = aux;
- /* Set up stack. */
- t->stack = (uint32_t *) ((uint8_t *) t + NBPG);
- *--t->stack = (uint32_t) aux;
- *--t->stack = (uint32_t) function;
- --t->stack;
- *--t->stack = (uint32_t) thread_root;
- t->stack -= 4;
+ /* Stack frame for switch_entry(). */
+ ef = alloc_frame (t, sizeof *ef);
+ ef->eip = (void (*) (void)) thread_root;
- /* Add to run_queue. */
- t->status = THREAD_BLOCKED;
+ /* Stack frame for thread_switch(). */
+ sf = alloc_frame (t, sizeof *sf);
+ sf->eip = switch_entry;
+
+ /* Add to run queue. */
thread_ready (t);
return t;
}
-static struct thread *
-stack_to_thread (uint32_t *stack)
-{
- return (struct thread *) ((uint32_t) (stack - 1) & ~((uint32_t) NBPG - 1));
-}
-
struct thread *
thread_current (void)
{
uint32_t *esp;
asm ("movl %%esp, %0\n" : "=g" (esp));
- return stack_to_thread (esp);
+ return pg_round_down (esp);
}
#ifdef USERPROG
-void
+bool
thread_execute (const char *filename)
{
- struct thread *t = thread_current ();
+ struct thread *t;
+ struct intr_frame *if_;
+ struct switch_entry_frame *ef;
+ struct switch_threads_frame *sf;
+ void (*start) (void);
+
+ ASSERT (filename != NULL);
+
+ t = new_thread (filename);
+ if (t == NULL)
+ return false;
- if (!addrspace_load (&t->addrspace, filename))
+ if (!addrspace_load (&t->addrspace, filename, &start))
panic ("%s: program load failed", filename);
- panic ("%s: loaded", filename);
+
+ /* Interrupt frame. */
+ if_ = alloc_frame (t, sizeof *if_);
+ if_->es = SEL_UDSEG;
+ if_->ds = SEL_UDSEG;
+ if_->eip = start;
+ if_->cs = SEL_UCSEG;
+ if_->eflags = FLAG_IF | 2;
+ if_->esp = PHYS_BASE;
+ if_->ss = SEL_UDSEG;
+
+ /* Stack frame for switch_entry(). */
+ ef = alloc_frame (t, sizeof *ef);
+ ef->eip = intr_exit;
+
+ /* Stack frame for thread_switch(). */
+ sf = alloc_frame (t, sizeof *sf);
+ sf->eip = switch_entry;
+
+ /* Add to run queue. */
+ thread_ready (t);
+
+ return true;
}
#endif
palloc_free (t);
}
+void schedule_tail (struct thread *prev);
+
void
+schedule_tail (struct thread *prev)
+{
+ struct thread *cur = thread_current ();
+
+ ASSERT (intr_get_level () == IF_OFF);
+
+#ifdef USERPROG
+ addrspace_activate (&cur->addrspace);
+#endif
+
+ if (prev != NULL && prev->status == THREAD_DYING)
+ thread_destroy (prev);
+}
+
+static void
thread_schedule (void)
{
struct thread *cur, *next, *prev;
idle ();
next->status = THREAD_RUNNING;
- prev = thread_switch (cur, next);
-
- /* Prevent GCC from reordering anything around the thread
- switch. */
- asm volatile ("" : : : "memory");
+ if (cur != next)
+ {
+ prev = switch_threads (cur, next);
- if (prev != NULL && prev->status == THREAD_DYING)
- thread_destroy (prev);
+ /* Prevent GCC from reordering anything around the thread
+ switch. */
+ asm volatile ("" : : : "memory");
- intr_enable ();
+ schedule_tail (prev);
+ }
}
void
thread_yield (void)
{
+ enum if_level old_level;
+
ASSERT (!intr_context ());
- intr_disable ();
+ old_level = intr_disable ();
thread_ready (thread_current ());
thread_schedule ();
+ intr_set_level (old_level);
}
void
if (t->status == THREAD_READY)
list_remove (&t->rq_elem);
t->status = THREAD_RUNNING;
- thread_switch (NULL, t);
+ switch_threads (NULL, t);
}
void
intr_disable ();
thread_current ()->status = THREAD_DYING;
thread_schedule ();
+ NOT_REACHED ();
}
void