2006-09-06 19:50:20 +02:00
|
|
|
// Physical memory allocator, intended to allocate
|
2010-08-31 18:54:47 +02:00
|
|
|
// memory for user processes, kernel stacks, page table pages,
|
|
|
|
// and pipe buffers. Allocates 4096-byte pages.
|
2006-06-12 17:22:12 +02:00
|
|
|
|
|
|
|
#include "types.h"
|
|
|
|
#include "defs.h"
|
2006-07-12 13:15:38 +02:00
|
|
|
#include "param.h"
|
2010-07-02 20:51:53 +02:00
|
|
|
#include "mmu.h"
|
2006-07-12 03:48:35 +02:00
|
|
|
#include "spinlock.h"
|
|
|
|
|
2006-06-12 17:22:12 +02:00
|
|
|
struct run {
|
|
|
|
struct run *next;
|
|
|
|
};
|
2009-05-31 07:12:21 +02:00
|
|
|
|
|
|
|
struct {
|
|
|
|
struct spinlock lock;
|
|
|
|
struct run *freelist;
|
|
|
|
} kmem;
|
2006-06-12 17:22:12 +02:00
|
|
|
|
2006-09-06 19:50:20 +02:00
|
|
|
// Initialize free list of physical pages.
|
2006-06-12 17:22:12 +02:00
|
|
|
void
|
2010-08-31 21:39:25 +02:00
|
|
|
kinit(void)
|
2006-06-12 17:22:12 +02:00
|
|
|
{
|
2010-08-31 21:39:25 +02:00
|
|
|
extern char end[];
|
|
|
|
|
2009-05-31 07:12:21 +02:00
|
|
|
initlock(&kmem.lock, "kmem");
|
2010-08-31 21:39:25 +02:00
|
|
|
char *p1 = (char*)PGROUNDUP((uint)end);
|
|
|
|
char *p2 = PGROUNDDOWN(PHYSTOP);
|
2010-08-31 18:54:47 +02:00
|
|
|
for( ; p1 < p2; p1 += 4096)
|
|
|
|
kfree(p1);
|
2006-06-12 17:22:12 +02:00
|
|
|
}
|
|
|
|
|
2010-08-31 18:54:47 +02:00
|
|
|
// Free the page of physical memory pointed at by v,
|
2006-09-07 16:12:30 +02:00
|
|
|
// which normally should have been returned by a
|
2010-08-31 18:54:47 +02:00
|
|
|
// call to kalloc(). (The exception is when
|
2006-09-07 16:12:30 +02:00
|
|
|
// initializing the allocator; see kinit above.)
|
2006-06-12 17:22:12 +02:00
|
|
|
void
|
2010-08-31 18:54:47 +02:00
|
|
|
kfree(char *v)
|
2006-06-12 17:22:12 +02:00
|
|
|
{
|
2010-08-31 18:54:47 +02:00
|
|
|
struct run *r;
|
2006-06-12 17:22:12 +02:00
|
|
|
|
2010-08-31 18:54:47 +02:00
|
|
|
if(((uint) v) % PGSIZE || (uint)v < 1024*1024 || (uint)v >= PHYSTOP)
|
2006-06-12 17:22:12 +02:00
|
|
|
panic("kfree");
|
|
|
|
|
2006-09-06 20:06:04 +02:00
|
|
|
// Fill with junk to catch dangling refs.
|
2010-08-31 18:54:47 +02:00
|
|
|
memset(v, 1, PGSIZE);
|
2006-07-01 23:26:01 +02:00
|
|
|
|
2009-05-31 07:12:21 +02:00
|
|
|
acquire(&kmem.lock);
|
2010-08-31 18:54:47 +02:00
|
|
|
r = (struct run *) v;
|
|
|
|
r->next = kmem.freelist;
|
|
|
|
kmem.freelist = r;
|
2009-05-31 07:12:21 +02:00
|
|
|
release(&kmem.lock);
|
2006-06-12 17:22:12 +02:00
|
|
|
}
|
|
|
|
|
2010-08-31 18:54:47 +02:00
|
|
|
// Allocate one 4096-byte page of physical memory.
|
|
|
|
// Returns a pointer that the kernel can use.
|
2006-09-06 19:50:20 +02:00
|
|
|
// Returns 0 if the memory cannot be allocated.
|
2006-07-16 18:05:37 +02:00
|
|
|
char*
|
2010-08-31 18:54:47 +02:00
|
|
|
kalloc()
|
2006-06-12 17:22:12 +02:00
|
|
|
{
|
2010-08-31 18:54:47 +02:00
|
|
|
struct run *r;
|
2006-06-12 17:22:12 +02:00
|
|
|
|
2009-05-31 07:12:21 +02:00
|
|
|
acquire(&kmem.lock);
|
2010-08-31 18:54:47 +02:00
|
|
|
r = kmem.freelist;
|
|
|
|
if(r)
|
|
|
|
kmem.freelist = r->next;
|
2009-05-31 07:12:21 +02:00
|
|
|
release(&kmem.lock);
|
2010-08-31 18:54:47 +02:00
|
|
|
return (char*) r;
|
2006-06-12 17:22:12 +02:00
|
|
|
}
|
2010-07-02 20:51:53 +02:00
|
|
|
|