// Copy the mappings for shared pages into the child address space.
static int
copy_shared_pages(envid_t child)
{
// LAB 7: Your code here.
uint64_t vaddr;
int r;
for(vaddr=0; vaddr<UTOP; vaddr += PGSIZE) {
// Copying from lib/fork.c bruh.
if( // Gotta use the virtual types apparently.
(vpml4e[VPML4E(vaddr)] & PTE_P) // Mota mota level is present.
&& ((vpde[VPDPE(vaddr)] & PTE_U) && (vpde[VPDPE(vaddr)] & PTE_P)) // Slighlt less mota level is also present.
&& ((vpd[VPD(vaddr)] & PTE_U) && (vpd[VPD(vaddr)] & PTE_P))
&& ((vpt[VPN(vaddr)] & PTE_U) && (vpt[VPN(vaddr)] & PTE_P))
)
if(vpt[VPN(vaddr)]&PTE_SHARE) {
r = sys_page_map(0, (void*)vaddr, child, (void*)vaddr, vpt[VPN(vaddr)] & PTE_SYSCALL);
if(r<0) {
cprintf("WARN: Your environments are now throughly done for man.\n");
return -1;
}
}
}
return 0;
}
//
// User-level fork with copy-on-write.
// Set up our page fault handler appropriately.
// Create a child.
// Copy our address space and page fault handler setup to the child.
// Then mark the child as runnable and return.
//
// Returns: child's envid to the parent, 0 to the child, < 0 on error.
// It is also OK to panic on error.
//
// Hint:
// Use vpd, vpt, and duppage.
// Remember to fix "thisenv" in the child process.
// Neither user exception stack should ever be marked copy-on-write,
// so you must allocate a new page for the child's user exception stack.
//
envid_t
fork(void)
{
// LAB 4: Your code here.
envid_t envid;
uint64_t addr;
uint32_t err;
extern unsigned char end[];
int r;
set_pgfault_handler(pgfault);
envid = sys_exofork();
if (envid < 0)
panic("sys_exofork: %e", envid);
if (envid == 0) {
// We're the child.
// The copied value of the global variable 'thisenv'
// is no longer valid (it refers to the parent!).
// Fix it and return 0.
thisenv = &envs[ENVX(sys_getenvid())];
return 0;
}
//Allocate exception stack for the child
if ((err = sys_page_alloc(envid, (void *) (UXSTACKTOP - PGSIZE), PTE_P|PTE_U|PTE_W)) < 0)
panic("Error in sys_page_alloc: %e", err);
// We're the parent.
// Map our entire address space into the child.
for (addr = UTEXT; addr < USTACKTOP-PGSIZE; addr += PGSIZE) {
if((vpml4e[VPML4E(addr)] & PTE_P) && (vpde[VPDPE(addr)] & PTE_P)
&& (vpd[VPD(addr)] & PTE_P) && (vpt[VPN(addr)] & PTE_P)) {
duppage(envid, VPN(addr));
}
}
//Allocate a new stack for the child and copy the contents of parent on to it.
addr = USTACKTOP-PGSIZE;
if ((r = sys_page_alloc(0, (void *)PFTEMP, PTE_P|PTE_U|PTE_W)) < 0)
panic("sys_page_alloc failed: %e\n", r);
memcpy(PFTEMP, (void *) ROUNDDOWN(addr, PGSIZE), PGSIZE);
void *vaTemp = (void *) ROUNDDOWN(addr, PGSIZE);
if ((r = sys_page_map(0, (void *)PFTEMP, envid, vaTemp, PTE_P|PTE_U|PTE_W)) < 0)
panic("sys_page_map failed: %e\n", r);
if ((r = sys_page_unmap(0, (void *)PFTEMP)) < 0)
panic("sys_page_unmap failed: %e\n", r);
//Set child's page fault handler
if ((err = sys_env_set_pgfault_upcall(envid, _pgfault_upcall) < 0))
panic("Error in sys_env_set_pgfault_upcall: %e",err);
//Set the child ready to run
if ((err = sys_env_set_status(envid, ENV_RUNNABLE)) < 0)
panic("sys_env_set_status: %e", err);
return envid;
panic("fork not implemented");
}
//
// User-level fork with copy-on-write.
// Set up our page fault handler appropriately.
// Create a child.
// Copy our address space and page fault handler setup to the child.
// Then mark the child as runnable and return.
//
// Returns: child's envid to the parent, 0 to the child, < 0 on error.
// It is also OK to panic on error.
//
// Hint:
// Use vpd, vpt, and duppage.
// Remember to fix "thisenv" in the child process.
// Neither user exception stack should ever be marked copy-on-write,
// so you must allocate a new page for the child's user exception stack.
//
envid_t
fork(void)
{
// LAB 4: Your code here.
int r;
envid_t envid;
set_pgfault_handler(pgfault);
if((envid = sys_exofork())<0)
panic("sys_exofork error: %e\n",envid);
if(envid == 0){
thisenv = &envs[ENVX(sys_getenvid())];
return 0;
}
uint32_t vaddr;
extern unsigned char end[];
for (vaddr = 0 ; vaddr < UTOP; vaddr += PGSIZE ){
//Check sequentially
if ((vpml4e[VPML4E(vaddr)] & PTE_P ) && (vpde[VPDPE(vaddr)] & PTE_P ) && (vpd[VPD(vaddr)] & PTE_P )
&& (vpt[VPN(vaddr)] & PTE_P)){ //Order is imp...
if ((vaddr != (UXSTACKTOP - PGSIZE)) && (vaddr != (USTACKTOP - PGSIZE))){
duppage(envid, (uint64_t)vaddr / PGSIZE);
}
}
}
if ((r = sys_page_alloc(envid,(void*)(USTACKTOP - PGSIZE), PTE_U | PTE_W | PTE_P ))<0){
panic("error from sys_page_alloc: %e\n", r);
}
else
{
if ((r = sys_page_alloc(0, PFTEMP, PTE_U|PTE_W|PTE_P)) < 0)
panic("error from sys_page_alloc: %e", r);
memmove(PFTEMP, (void *)(USTACKTOP - PGSIZE), PGSIZE);
if ((r = sys_page_map(0,PFTEMP, envid, (void *)(USTACKTOP - PGSIZE) , PTE_U|PTE_W|PTE_P)) < 0)
panic("error from sys_page_map: %e", r);
}
if((r = sys_page_alloc(envid,(void*)(UXSTACKTOP - PGSIZE), PTE_U | PTE_W | PTE_P ))<0)
panic("error from sys_page_alloc : %e\n",r);
if((r=sys_env_set_pgfault_upcall(envid, thisenv->env_pgfault_upcall))!=0)
panic("error from sys_env_set_pgfault_upcall : %e\n",r);
if((r = sys_env_set_status(envid, ENV_RUNNABLE))<0)
panic("error from sys_env_set_status : %e\n",r);
return envid;
}
// Copy the mappings for shared pages into the child address space.
static int
copy_shared_pages(envid_t child)
{
// LAB 7: Your code here.
uint64_t addr;
for (addr = UTEXT; addr < USTACKTOP-PGSIZE; addr += PGSIZE) {
if((vpml4e[VPML4E(addr)] & PTE_P) && (vpde[VPDPE(addr)] & PTE_P)
&& (vpd[VPD(addr)] & PTE_P) && (vpt[VPN(addr)] & PTE_P)) {
int perm_share = vpt[VPN(addr)] & PTE_USER;
if (perm_share & PTE_SHARE)
sys_page_map(0, (void *)addr, child, (void *)addr, perm_share);
}
}
return 0;
}
int32_t net_host_send(char *pg, int len) {
// LAB 8: Your code here.
if (pg == NULL)
pg = (void*) UTOP;
uint64_t addr = (uint64_t)pg;
if( (vpml4e[VPML4E(addr)] & PTE_P) && (vpde[VPDPE(addr)] & PTE_P)
&& (vpd[VPD(addr)] & PTE_P) && (vpt[VPN(addr)] & PTE_P) )
{
pg = (void *) PTE_ADDR( vpt[VPN(addr)] );
}
int ret = vm_call( VMX_VMCALL_NETSEND, (uint64_t) pg , (uint64_t) len, 0, 0, 0 );
return ret;
}
// The parent installs pgfault() as the C-level page fault handler, using the set_pgfault_handler() function you implemented above.
// The parent calls sys_exofork() to create a child environment.
// For each writable or copy-on-write page in its address space below UTOP, the parent calls duppage, which should map the page copy-on-write into the address space of the child and then remap the page copy-on-write in its own address space. duppage sets both PTEs so that the page is not writeable, and to contain PTE_COW in the "avail" field to distinguish copy-on-write pages from genuine read-only pages.
// The exception stack is not remapped this way, however. Instead you need to allocate a fresh page in the child for the exception stack.
// Since the page fault handler will be doing the actual copying and the page fault handler runs on the exception stack, the exception stack cannot be made copy-on-write: who would copy it?
// fork() also needs to handle pages that are present, but not writable or copy-on-write.
// The parent sets the user page fault entrypoint for the child to look like its own.
// The child is now ready to run, so the parent marks it runnable.
//
// User-level fork with copy-on-write.
// Set up our page fault handler appropriately.
// Create a child.
// Copy our address space and page fault handler setup to the child.
// Then mark the child as runnable and return.
//
// Returns: child's envid to the parent, 0 to the child, < 0 on error.
// It is also OK to panic on error.
//
// Hint:
// Use vpd, vpt, and duppage.
// Remember to fix "thisenv" in the child process.
// Neither user exception stack should ever be marked copy-on-write,
// so you must allocate a new page for the child's user exception stack.
//
envid_t
fork(void)
{
// LAB 4: Your code here.
set_pgfault_handler(pgfault);
envid_t eid = sys_exofork();
if(eid < 0) // error
panic("couldn't fork child. %e",eid);
else if(eid == 0) { // child
thisenv = envs+ENVX(sys_getenvid());
return 0;
}
else { //parent
uint64_t r;
for (r = 0; r < (uint64_t)(UXSTACKTOP-PGSIZE); r += PGSIZE) {
if( (vpml4e[VPML4E(r)] & PTE_P) &&
(vpde[VPDPE(r)] & PTE_P) &&
(vpd[VPD(r)] & PTE_P) &&
(vpt[VPN(r)] & PTE_P))
{
duppage(eid, VPN(r));
}
}
//Duppage the stack for the child
duppage(eid, VPN(USTACKTOP-PGSIZE));
// Instead you need to allocate a fresh page in the child for the exception stack
if((r= sys_page_alloc(eid, (void *)(UXSTACKTOP-PGSIZE), PTE_U|PTE_P|PTE_W)) < 0)
panic("fork failed setting UXSTACK for child %e", r);
//The parent sets the user page fault entrypoint for the child to look like its own.
if((r= sys_env_set_pgfault_upcall(eid, thisenv->env_pgfault_upcall)) < 0) //
panic("fork failed setting pgfault handler %e", r);
//The child is now ready to run, so the parent marks it runnable.
if((r= sys_env_set_status(eid, ENV_RUNNABLE)) < 0)
panic("fork failed setting status %e", r);
//cprintf("forked the child\n");
return eid;
}
//panic("fork not implemented");
}
// Is this virtual address mapped?
bool
va_is_mapped(void *va)
{
return (vpml4e[VPML4E(va)] & PTE_P) && (vpde[VPDPE(va)] & PTE_P) && (vpd[VPD(va)] & PTE_P) && (vpt[PPN(va)] & PTE_P);
}
