Jos - lab4 (Part A) System Calls for Environment Creation

Exercise 7.Implement the system calls described abovein kern/syscall.c.You will need to use various functionsin kern/pmap.c and kern/env.c,particularly envid2env().For now, whenever you call envid2env(),pass 1 in the checkperm parameter.Be sure you check for any invalid system call arguments,returning -E_INVAL in that case.Test your JOS kernel with user/dumbforkand make sure it works before proceeding.

sys_exofork:

 89         struct Env *e;
 90         int r = env_alloc(&e, curenv->env_id);
 91         if (r < 0) {
 92                 cprintf("%s(),%d: return %d!\n",__func__,__LINE__,r);
 93                 return r;
 94         }
 95         e->env_status = ENV_NOT_RUNNABLE;
 96         memmove((void *)&e->env_tf,(void *)&curenv->env_tf,sizeof(struct Trapf    rame));
 97         e->env_tf.tf_regs.reg_eax = 0;
 98         return e->env_id;

sys_env_set_status:

118         struct Env *e = NULL;
119         if ((status != ENV_RUNNABLE) && (status != ENV_NOT_RUNNABLE)) {
120                 cprintf("%s(),%d!\n",__func__,__LINE__);
121                 return -E_INVAL;
122         }
123         int r = envid2env(envid, &e, 1);
124         if (r < 0){
125                 cprintf("%s(),%d: return %d!\n",__func__,__LINE__,r);
126                 return r;
127         }
128         e->env_status = status;
129         return 0;

sys_page_alloc:
174         struct Env *e;
175         if (((uint32_t)va >= UTOP) || ((uint32_t)va % PGSIZE != 0) || ((perm&(    ~PTE_SYSCALL)) != 0)){
176                 cprintf("%s(),%d!\n",__func__,__LINE__);
177                 return -E_INVAL;
178         }
179         int r = envid2env(envid, &e, 1);
180         if (r < 0) {
181                 cprintf("%s(),%d: return %d!\n",__func__,__LINE__,r);
182                 return r;
183         }
184         struct PageInfo *p = page_alloc(ALLOC_ZERO);
185         if (p == NULL) {
186                 cprintf("%s(),%d!\n",__func__,__LINE__);
187                 return -E_NO_MEM;
188         }
189         r = page_insert(e->env_pgdir, p, va, perm);
190         if (r < 0) {
191                 page_free(p);
192                 cprintf("%s(),%d: return %d!\n",__func__,__LINE__,r);
193                 return r;
194         }
195         return 0;

sys_page_map:
226         if (((uint32_t)srcva >= UTOP) || ((uint32_t)srcva % PGSIZE != 0) || ((    uint32_t)dstva >= UTOP) || ((uint32_t)dstva % PGSIZE != 0) || ((perm&(~PTE_SYS    CALL)) != 0))
227                 return -E_INVAL;
228         pte_t *pte;
229         struct Env *srce,*dste;
230         if ((envid2env(srcenvid, &srce, 1) < 0) || (envid2env(dstenvid, &dste,     1) < 0)) {
231                 cprintf("%s(),%d: return !\n",__func__,__LINE__);
232                 return -E_BAD_ENV;
233         }
234         struct PageInfo *p = page_lookup(srce->env_pgdir, srcva, &pte);
235         if ((p == NULL) || (~(*pte) & perm & PTE_W)) {
236         //      cprintf("%s(),%d: (*pte) = 0x%x!\n",__func__,__LINE__, (*pte))    ;
237                 return -E_INVAL;
238         }
239         return page_insert(dste->env_pgdir, p, dstva, perm);

sys_page_unmap:
255         struct Env *env;
256         if (((uint32_t)va >= UTOP) || ((uint32_t)va % PGSIZE != 0)){
257                 cprintf("%s(),%d: !\n",__func__,__LINE__);
258                 return -E_INVAL;
259         }
260         if (envid2env(envid, &env, 1) < 0){
261                 cprintf("%s(),%d: return!\n",__func__,__LINE__);
262                 return -E_BAD_ENV;
263         }
264         page_remove(env->env_pgdir, va);
265         return 0;