1 #include "types.h" 2 #include "param.h" 3 #include "mmu.h" 4 #include "proc.h" 5 #include "defs.h" 6 #include "x86.h" 7 #include "elf.h" 8 9 int 10 exec(char *path, char **argv) 11 { 12 char *s, *last; 13 int i, off; 14 uint argc, sz, sp, ustack[3+MAXARG+1]; 15 struct elfhdr elf; 16 struct inode *ip; 17 struct proghdr ph; 18 pde_t *pgdir, *oldpgdir; 19 20 if((ip = namei(path)) == 0) 21 return -1; 22 ilock(ip); 23 pgdir = 0; 24 25 // Check ELF header 26 if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf)) 27 goto bad; 28 if(elf.magic != ELF_MAGIC) 29 goto bad; 30 31 if((pgdir = setupkvm()) == 0) 32 goto bad; 33 34 // Load program into memory. 35 sz = 0; 36 for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){ 37 if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph)) 38 goto bad; 39 if(ph.type != ELF_PROG_LOAD) 40 continue; 41 if(ph.memsz < ph.filesz) 42 goto bad; 43 if((sz = allocuvm(pgdir, sz, ph.va + ph.memsz)) == 0) 44 goto bad; 45 if(loaduvm(pgdir, (char*)ph.va, ip, ph.offset, ph.filesz) < 0) 46 goto bad; 47 } 48 iunlockput(ip); 49 ip = 0; 50 51 // Allocate a one-page stack at the next page boundary 52 sz = PGROUNDUP(sz); 53 if((sz = allocuvm(pgdir, sz, sz + PGSIZE)) == 0) 54 goto bad; 55 56 // Push argument strings, prepare rest of stack in ustack. 57 sp = sz; 58 for(argc = 0; argv[argc]; argc++) { 59 if(argc >= MAXARG) 60 goto bad; 61 sp -= strlen(argv[argc]) + 1; 62 sp &= ~3; 63 if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0) 64 goto bad; 65 ustack[3+argc] = sp; 66 } 67 ustack[3+argc] = 0; 68 69 ustack[0] = 0xffffffff; // fake return PC 70 ustack[1] = argc; 71 ustack[2] = sp - (argc+1)*4; // argv pointer 72 73 sp -= (3+argc+1) * 4; 74 if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0) 75 goto bad; 76 77 // Save program name for debugging. 78 for(last=s=path; *s; s++) 79 if(*s == '/') 80 last = s+1; 81 safestrcpy(proc->name, last, sizeof(proc->name)); 82 83 // Commit to the user image. 84 oldpgdir = proc->pgdir; 85 proc->pgdir = pgdir; 86 proc->sz = sz; 87 proc->tf->eip = elf.entry; // main 88 proc->tf->esp = sp; 89 switchuvm(proc); 90 freevm(oldpgdir); 91 92 return 0; 93 94 bad: 95 if(pgdir) 96 freevm(pgdir); 97 if(ip) 98 iunlockput(ip); 99 return -1; 100 } 101