Jos-lab2 (Challenges)

Challenge!Extend the JOS kernel monitor with commands to:

• Display in a useful and easy-to-read formatall of the physical page mappings (or lack thereof)that apply to a particular range of virtual/linear addressesin the currently active address space.For example,you might enter 'showmappings 0x3000 0x5000'to display the physical page mappingsand corresponding permission bitsthat apply to the pagesat virtual addresses 0x3000, 0x4000, and 0x5000.

 63 mon_showmappings(int argc, char **argv, struct Trapframe *tf)
 64 {
 65         uint32_t start, end;
 66         pte_t *pte;
 67         if (argc != 3) {
 68                 cprintf("Usage: showmappings [LOWER_ADDR][UPPER_ADDR]\n"    );
 69                 cprintf("Both address should be aligned in 4kb\n");
 70                 return 0;
 71         }
 72         start = strtol(argv[1],0,0);
 73         end = strtol(argv[2],0,0);
 74
 75         if (start != ROUNDUP(start, PGSIZE) ||
 76             end != ROUNDUP(end, PGSIZE) ||
 77             start > end) {
 78                 cprintf("Invalid address\n");
 79                 return 0;
 80         }
 81         while (start < end) {
 82                 pte = pgdir_walk(kern_pgdir, (void *)start, 0);
 83                 cprintf("0x%x ~ 0x%x: ",start, start + PGSIZE);
 84                 if (pte == NULL) {
 85                         cprintf("Not mapped!\n");
 86                 } else {
 87                         cprintf("0x%x\n",PTE_ADDR(*pte));
 88                         if (*pte & PTE_U)
 89                                 cprintf("user:");
 90                         else
 91                                 cprintf("kernel:");
 92                         if (*pte & PTE_W)
 93                                 cprintf("read/write\n");
 94                         else
 95                                 cprintf("read only\n");
 96                 }
 97                 start += PGSIZE;
 98         }
 99         return 0;
100 }

• Explicitly set, clear, or change the permissions of any mapping in the current address space.

 64 mon_setmappings(int argc, char **argv, struct Trapframe *tf)
 65 {
 66         if (argc != 3) {
 67                 cprintf("Usage: setmappings [VIRTURAL_ADDR] [PERMISSION]    \n");
 68                 cprintf("address should be aligned in 4kb, permission sh    ould \n \
 69                          be a combination of u/k and r/w. \n \
 70                          u:user, k:kernel, r:readonly, w:read/write.\n")    ;
 71                 return 0;
 72         }
 73         uint32_t va = strtol(argv[1],0,0);
 74         char* perm = argv[2];
 75         if (va != ROUNDUP(va, PGSIZE)) {
 76                 cprintf("Invalid address: 0x%x!\n",va);
 77                 return 0;
 78         }
 79         if (((perm[0] != 'k') && (perm[0] != 'u')) ||
 80                 ((perm[1] != 'r') && (perm[1] != 'w'))) {
 81                 cprintf("Invalid permission!\n");
 82                 return 0;
 83         }
 84         pte_t *pte = pgdir_walk(kern_pgdir, (void *)va, 0);
 85         if (!pte) {
 86                 cprintf("Address not mapped!\n");
 87                 return 0;
 88         }
 89         if (perm[0] == 'u')
 90                 *pte = (*pte) | PTE_U;
 91         else
 92                 *pte = (*pte) & (~PTE_U);
 93         if (perm[1] == 'w')
 94                 *pte = (*pte) | PTE_W;
 95         else
 96                 *pte = (*pte) & (~PTE_W);
 97         cprintf("set 0x%x permission as 0x%x!\n",va, PGOFF(*pte));
 98         return 0;
 99 }

• Dump the contents of a range of memory given either a virtual or physical address range.Be sure the dump code behaves correctly when the range extends across page boundaries!

 65 mon_dumpmem(int argc, char **argv, struct Trapframe *tf)
 66 {
 67         if (argc != 4) {
 68                 cprintf("Usage: dumpmem [ADDR_TYPE] [LOWER_ADDR] [DWORD]    \n");
 69                 cprintf("ADDR_TYPE should be 'v' or 'p'. v: virtual addr    ess, p: physical address.\n");
 70                 return 0;
 71         }
 72         uint32_t la,ua;
 73         int i;
 74         if (argv[1][0] == 'p') {
 75                 la = strtol(argv[2],0,0) + KERNBASE;
 76                 ua = la + strtol(argv[3],0,0)*4;
 77         } else if (argv[1][0] == 'v') {
 78                 la = strtol(argv[2],0,0);
 79                 ua = la + strtol(argv[3],0,0)*4;
 80         } else {
 81                 cprintf("Invalid ADDR TYPE!\n");
 82                 return 0;
 83         }
 84         if (la >= ua ||
 85             la != ROUNDUP(la, 4) ||
 86             ua != ROUNDUP(ua, 4)) {
 87                 cprintf("Invalid ADDR (0x%x, 0x%x)!\n",la,ua);
 88                 return 0;
 89         }
 90         for(i=0 ;la < ua; la += 4) {
 91                 if(!(i%4))
 92                         cprintf("\n0x%x: ",la);
 93                 cprintf("0x%x\t",*((uint32_t *)(la)));
 94                 i++;
 95         }
 96         cprintf("\n");
 97         return 0;
 98 }