fix allocuvm() to handle sbrk() with non-page-granularity argument
(maybe this never worked, but it works now)
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b738a4f1a2
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eb18645f17
5 changed files with 65 additions and 13 deletions
2
Makefile
2
Makefile
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@ -38,7 +38,7 @@ AS = $(TOOLPREFIX)gas
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LD = $(TOOLPREFIX)ld
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OBJCOPY = $(TOOLPREFIX)objcopy
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OBJDUMP = $(TOOLPREFIX)objdump
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CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32
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CFLAGS = -fno-pic -static -fno-builtin -fno-strict-aliasing -O2 -Wall -MD -ggdb -m32 -Werror
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CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
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ASFLAGS = -m32 -gdwarf-2
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# FreeBSD ld wants ``elf_i386_fbsd''
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2
defs.h
2
defs.h
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@ -153,8 +153,6 @@ void uartintr(void);
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void uartputc(int);
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// vm.c
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#define PGROUNDUP(sz) ((sz+PGSIZE-1) & ~(PGSIZE-1))
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extern pde_t *kpgdir;
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void pminit(void);
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void ksegment(void);
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void kvmalloc(void);
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4
mmu.h
4
mmu.h
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@ -126,6 +126,9 @@ struct segdesc {
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#define PTXSHIFT 12 // offset of PTX in a linear address
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#define PDXSHIFT 22 // offset of PDX in a linear address
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#define PGROUNDUP(sz) (((sz)+PGSIZE-1) & ~(PGSIZE-1))
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#define PGROUNDDOWN(a) ((char*)((((unsigned int)a) & ~(PGSIZE-1))))
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// Page table/directory entry flags.
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#define PTE_P 0x001 // Present
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#define PTE_W 0x002 // Writeable
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@ -148,6 +151,7 @@ struct segdesc {
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#define PTE_ADDR(pte) ((uint) (pte) & ~0xFFF)
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typedef uint pte_t;
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extern pde_t *kpgdir;
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// Control Register flags
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#define CR0_PE 0x00000001 // Protection Enable
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34
usertests.c
34
usertests.c
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@ -1229,6 +1229,38 @@ forktest(void)
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printf(1, "fork test OK\n");
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}
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void
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sbrktest(void)
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{
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printf(stdout, "sbrk test\n");
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char *a = sbrk(0);
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int i;
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for(i = 0; i < 5000; i++){
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char *b = sbrk(1);
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if(b != a){
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printf(stdout, "sbrk test failed %d %x %x\n", i, a, b);
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exit();
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}
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*b = 1;
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a = b + 1;
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}
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int pid = fork();
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if(pid < 0){
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printf(stdout, "sbrk test fork failed\n");
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exit();
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}
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char *c = sbrk(1);
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c = sbrk(1);
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if(c != a + 1){
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printf(stdout, "sbrk test failed post-fork\n");
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exit();
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}
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if(pid == 0)
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exit();
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wait();
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printf(stdout, "sbrk test OK\n");
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}
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int
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main(int argc, char *argv[])
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{
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@ -1240,6 +1272,8 @@ main(int argc, char *argv[])
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}
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close(open("usertests.ran", O_CREATE));
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sbrktest();
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opentest();
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writetest();
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writetest1();
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32
vm.c
32
vm.c
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@ -54,6 +54,9 @@ printpgdir(pde_t *pgdir)
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cprintf("printpgdir done\n", pgdir);
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}
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// return the address of the PTE in page table pgdir
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// that corresponds to linear address va. if create!=0,
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// create any required page table pages.
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static pte_t *
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walkpgdir(pde_t *pgdir, const void *va, int create)
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{
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@ -80,6 +83,8 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
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return &pgtab[PTX(va)];
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}
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// create PTEs for linear addresses starting at la that refer to
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// physical addresses starting at pa.
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static int
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mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
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{
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@ -89,6 +94,8 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
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for (i = 0; i < size; i += PGSIZE) {
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if (!(pte = walkpgdir(pgdir, (void*)(la + i), 1)))
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return 0;
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if(*pte & PTE_P)
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panic("remap");
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*pte = (pa + i) | perm | PTE_P;
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}
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return 1;
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@ -177,21 +184,30 @@ uva2ka(pde_t *pgdir, char *uva)
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return (char *)pa;
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}
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// allocate sz bytes more memory for a process starting at the
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// given user address; allocates physical memory and page
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// table entries. addr and sz need not be page-aligned.
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// it is a no-op for any parts of the requested memory
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// that are already allocated.
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int
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allocuvm(pde_t *pgdir, char *addr, uint sz)
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{
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uint i, n;
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char *mem;
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n = PGROUNDUP(sz);
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if (addr + n >= USERTOP)
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if (addr + sz >= (char*)USERTOP)
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return 0;
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for (i = 0; i < n; i += PGSIZE) {
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if (!(mem = kalloc(PGSIZE))) { // XXX cleanup what we did?
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char *start = PGROUNDDOWN(addr);
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char *last = PGROUNDDOWN(addr + sz - 1);
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char *a;
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for(a = start; a <= last; a += PGSIZE){
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pte_t *pte = walkpgdir(pgdir, a, 0);
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if(pte == 0 || (*pte & PTE_P) == 0){
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char *mem = kalloc(PGSIZE);
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if(mem == 0){
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// XXX clean up?
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return 0;
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}
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memset(mem, 0, PGSIZE);
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mappages(pgdir, addr + i, PGSIZE, PADDR(mem), PTE_W|PTE_U);
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mappages(pgdir, a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
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}
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}
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return 1;
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}
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