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authorAustin Clements <[email protected]>2010-09-02 18:28:36 -0400
committerAustin Clements <[email protected]>2010-09-02 18:28:36 -0400
commit79cd8b3eedeb1f85d3b19fb6119bd5224c4c532a (patch)
treef9afe121e2b9298b35d3ccd61a329f03421c97fa
parentd49d31381df93b40c1c4bc18c97ca42c3256e414 (diff)
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Simplify allocuvm/deallocuvm to operate in a contiguous memory model. This makes their interface match up better with proc->sz and also simplifies the callers (it even gets the main body of exec on one page).
-rw-r--r--defs.h4
-rw-r--r--exec.c26
-rw-r--r--proc.c7
-rw-r--r--vm.c58
4 files changed, 44 insertions, 51 deletions
diff --git a/defs.h b/defs.h
index cc3a721..4de95ad 100644
--- a/defs.h
+++ b/defs.h
@@ -157,8 +157,8 @@ void kvmalloc(void);
void vmenable(void);
pde_t* setupkvm(void);
char* uva2ka(pde_t*, char*);
-int allocuvm(pde_t*, char*, uint);
-int deallocuvm(pde_t *pgdir, char *addr, uint sz);
+int allocuvm(pde_t*, uint, uint);
+int deallocuvm(pde_t*, uint, uint);
void freevm(pde_t*);
void inituvm(pde_t*, char*, uint);
int loaduvm(pde_t*, char*, struct inode *ip, uint, uint);
diff --git a/exec.c b/exec.c
index c518c04..222f64c 100644
--- a/exec.c
+++ b/exec.c
@@ -11,7 +11,7 @@ exec(char *path, char **argv)
{
char *mem, *s, *last;
int i, argc, arglen, len, off;
- uint sz, sp, spoffset, argp;
+ uint sz, sp, spbottom, argp;
struct elfhdr elf;
struct inode *ip;
struct proghdr ph;
@@ -41,22 +41,18 @@ exec(char *path, char **argv)
continue;
if(ph.memsz < ph.filesz)
goto bad;
- if(!allocuvm(pgdir, (char *)ph.va, ph.memsz))
+ if(!(sz = allocuvm(pgdir, sz, ph.va + ph.memsz)))
goto bad;
- if(ph.va + ph.memsz > sz)
- sz = ph.va + ph.memsz;
if(!loaduvm(pgdir, (char *)ph.va, ip, ph.offset, ph.filesz))
goto bad;
}
iunlockput(ip);
// Allocate and initialize stack at sz
- sz = PGROUNDUP(sz);
- if(!allocuvm(pgdir, (char *)sz, PGSIZE))
+ sz = spbottom = PGROUNDUP(sz);
+ if(!(sz = allocuvm(pgdir, sz, sz + PGSIZE)))
goto bad;
- mem = uva2ka(pgdir, (char *)sz);
- spoffset = sz;
- sz += PGSIZE;
+ mem = uva2ka(pgdir, (char *)spbottom);
arglen = 0;
for(argc=0; argv[argc]; argc++)
@@ -67,22 +63,22 @@ exec(char *path, char **argv)
argp = sz - arglen - 4*(argc+1);
// Copy argv strings and pointers to stack.
- *(uint*)(mem+argp-spoffset + 4*argc) = 0; // argv[argc]
+ *(uint*)(mem+argp-spbottom + 4*argc) = 0; // argv[argc]
for(i=argc-1; i>=0; i--){
len = strlen(argv[i]) + 1;
sp -= len;
- memmove(mem+sp-spoffset, argv[i], len);
- *(uint*)(mem+argp-spoffset + 4*i) = sp; // argv[i]
+ memmove(mem+sp-spbottom, argv[i], len);
+ *(uint*)(mem+argp-spbottom + 4*i) = sp; // argv[i]
}
// Stack frame for main(argc, argv), below arguments.
sp = argp;
sp -= 4;
- *(uint*)(mem+sp-spoffset) = argp;
+ *(uint*)(mem+sp-spbottom) = argp;
sp -= 4;
- *(uint*)(mem+sp-spoffset) = argc;
+ *(uint*)(mem+sp-spbottom) = argc;
sp -= 4;
- *(uint*)(mem+sp-spoffset) = 0xffffffff; // fake return pc
+ *(uint*)(mem+sp-spbottom) = 0xffffffff; // fake return pc
// Save program name for debugging.
for(last=s=path; *s; s++)
diff --git a/proc.c b/proc.c
index 853eb0a..6f7bdb6 100644
--- a/proc.c
+++ b/proc.c
@@ -142,14 +142,15 @@ userinit(void)
int
growproc(int n)
{
+ uint sz = proc->sz;
if(n > 0){
- if(!allocuvm(proc->pgdir, (char *)proc->sz, n))
+ if(!(sz = allocuvm(proc->pgdir, sz, sz + n)))
return -1;
} else if(n < 0){
- if(!deallocuvm(proc->pgdir, (char *)(proc->sz + n), 0 - n))
+ if(!(sz = deallocuvm(proc->pgdir, sz, sz + n)))
return -1;
}
- proc->sz += n;
+ proc->sz = sz;
switchuvm(proc);
return 0;
}
diff --git a/vm.c b/vm.c
index 0104c3e..5c6f943 100644
--- a/vm.c
+++ b/vm.c
@@ -228,54 +228,50 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
return 1;
}
-// Allocate sz bytes more memory for a process starting at the
-// given user address; allocates physical memory and page
-// table entries. addr and sz need not be page-aligned.
-// It is a no-op for any parts of the requested memory
-// that are already allocated.
+// Allocate memory to the process to bring its size from oldsz to
+// newsz. Allocates physical memory and page table entries. oldsz and
+// newsz need not be page-aligned, nor does newsz have to be larger
+// than oldsz. Returns the new process size or 0 on error.
int
-allocuvm(pde_t *pgdir, char *addr, uint sz)
+allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
- if(addr + sz > (char*)USERTOP)
+ if(newsz > USERTOP)
return 0;
- char *a = PGROUNDDOWN(addr);
- char *last = PGROUNDDOWN(addr + sz - 1);
- for(; a <= last; a += PGSIZE){
- pte_t *pte = walkpgdir(pgdir, a, 0);
- if(pte == 0 || (*pte & PTE_P) == 0){
- char *mem = kalloc();
- if(mem == 0){
- cprintf("allocuvm out of memory\n");
- deallocuvm(pgdir, addr, sz);
- return 0;
- }
- memset(mem, 0, PGSIZE);
- mappages(pgdir, a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
+ char *a = (char *)PGROUNDUP(oldsz);
+ char *last = PGROUNDDOWN(newsz - 1);
+ for (; a <= last; a += PGSIZE){
+ char *mem = kalloc();
+ if(mem == 0){
+ cprintf("allocuvm out of memory\n");
+ deallocuvm(pgdir, newsz, oldsz);
+ return 0;
}
+ memset(mem, 0, PGSIZE);
+ mappages(pgdir, a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
}
- return 1;
+ return newsz > oldsz ? newsz : oldsz;
}
-// Deallocate some of the user pages. If addr is not page-aligned,
-// then only deallocates starting at the next page boundary.
+// Deallocate user pages to bring the process size from oldsz to
+// newsz. oldsz and newsz need not be page-aligned, nor does newsz
+// need to be less than oldsz. oldsz can be larger than the actual
+// process size. Returns the new process size.
int
-deallocuvm(pde_t *pgdir, char *addr, uint sz)
+deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
{
- if(addr + sz > (char*)USERTOP)
- return 0;
- char *a = (char *)PGROUNDUP((uint)addr);
- char *last = PGROUNDDOWN(addr + sz - 1);
+ char *a = (char *)PGROUNDUP(newsz);
+ char *last = PGROUNDDOWN(oldsz - 1);
for(; a <= last; a += PGSIZE){
pte_t *pte = walkpgdir(pgdir, a, 0);
if(pte && (*pte & PTE_P) != 0){
uint pa = PTE_ADDR(*pte);
if(pa == 0)
- panic("deallocuvm");
+ panic("kfree");
kfree((void *) pa);
*pte = 0;
}
}
- return 1;
+ return newsz < oldsz ? newsz : oldsz;
}
// Free a page table and all the physical memory pages
@@ -287,7 +283,7 @@ freevm(pde_t *pgdir)
if(!pgdir)
panic("freevm: no pgdir");
- deallocuvm(pgdir, 0, USERTOP);
+ deallocuvm(pgdir, USERTOP, 0);
for(i = 0; i < NPDENTRIES; i++){
if(pgdir[i] & PTE_P)
kfree((void *) PTE_ADDR(pgdir[i]));