132 lines
2.7 KiB
C
132 lines
2.7 KiB
C
// Physical memory allocator, for user processes,
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// kernel stacks, page-table pages,
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// and pipe buffers. Allocates whole 4096-byte pages.
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#include "types.h"
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#include "param.h"
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#include "memlayout.h"
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#include "spinlock.h"
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#include "riscv.h"
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#include "defs.h"
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void freerange(void *pa_start, void *pa_end);
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extern char end[]; // first address after kernel.
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// defined by kernel.ld.
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struct run {
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struct run *next;
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};
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struct {
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struct spinlock lock;
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struct run *freelist;
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} kmem;
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struct super_run {
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struct super_run *next;
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};
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struct {
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struct spinlock lock;
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struct super_run *freelist;
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} skmem;
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void superfree(void *pa) {
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struct super_run *r;
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if(((uint64)pa % SUPERPGSIZE) != 0 || (char*)pa < end || (uint64)pa >= PHYSTOP)
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panic("superfree");
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// Fill with junk to catch dangling refs.
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memset(pa, 1, SUPERPGSIZE);
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r = (struct super_run *)pa;
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acquire(&skmem.lock);
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r->next = skmem.freelist;
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skmem.freelist = r;
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release(&skmem.lock);
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}
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void* superalloc() {
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struct super_run *r;
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acquire(&skmem.lock);
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r = skmem.freelist;
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if(r) skmem.freelist = r->next;
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release(&skmem.lock);
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if(r) memset((void*)r, 0, SUPERPGSIZE);
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return (void*)r;
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}
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void
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kinit()
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{
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initlock(&kmem.lock, "kmem");
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initlock(&skmem.lock, "skmem");
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freerange(end, (void*)PHYSTOP);
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}
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void
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freerange(void *pa_start, void *pa_end)
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{
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char *p;
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p = (char*)PGROUNDUP((uint64)pa_start);
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for(; p + PGSIZE <= (char*)pa_end - 12 * 1024 * 1024; p += PGSIZE) //留5个巨页
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kfree(p);
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p = (char*)SUPERPGROUNDUP((uint64)p);
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for (; p + SUPERPGSIZE <= (char *)pa_end; p += SUPERPGSIZE) {
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superfree(p);
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}
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}
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// void
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// freerange(void *pa_start, void *pa_end)
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// {
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// char *p;
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// p = (char*)PGROUNDUP((uint64)pa_start);
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// for(; p + PGSIZE <= (char*)pa_end; p += PGSIZE)
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// kfree(p);
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// }
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// Free the page of physical memory pointed at by pa,
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// which normally should have been returned by a
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// call to kalloc(). (The exception is when
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// initializing the allocator; see kinit above.)
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void
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kfree(void *pa)
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{
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struct run *r;
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if(((uint64)pa % PGSIZE) != 0 || (char*)pa < end || (uint64)pa >= PHYSTOP)
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panic("kfree");
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// Fill with junk to catch dangling refs.
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memset(pa, 1, PGSIZE);
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r = (struct run*)pa;
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acquire(&kmem.lock);
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r->next = kmem.freelist;
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kmem.freelist = r;
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release(&kmem.lock);
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}
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// Allocate one 4096-byte page of physical memory.
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// Returns a pointer that the kernel can use.
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// Returns 0 if the memory cannot be allocated.
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void *
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kalloc(void)
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{
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struct run *r;
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acquire(&kmem.lock);
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r = kmem.freelist;
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if(r)
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kmem.freelist = r->next;
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release(&kmem.lock);
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if(r)
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memset((char*)r, 5, PGSIZE); // fill with junk
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return (void*)r;
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}
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