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1 #include "types.h"
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2 #include "param.h"
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3 #include "memlayout.h"
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4 #include "mmu.h"
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5 #include "proc.h"
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6 #include "defs.h"
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7 #include "arm.h"
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8 #include "elf.h"
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9
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10 int
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11 exec(char *path, char **argv)
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12 {
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13 char *last;
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14 int i, off;
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15 uint argc, sz, sp, ustack[3+MAXARG+1];
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16 struct elfhdr elf;
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17 struct inode *ip;
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18 struct proghdr ph;
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19 pde_t *pgdir, *oldpgdir;
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20
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21 if((ip = namei(path)) == 0)
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22 return -1;
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23 ilock(ip);
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24 pgdir = 0;
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25
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26 // Check ELF header
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27 if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
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28 goto bad;
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29 if(elf.magic != ELF_MAGIC)
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30 goto bad;
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31
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32 if((pgdir = setupkvm()) == 0)
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33 goto bad;
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34 // Load program into memory.
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35 sz = 0;
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36 for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
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37 if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
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38 goto bad;
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39 if(ph.type != ELF_PROG_LOAD)
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40 continue;
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41 if(ph.memsz < ph.filesz)
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42 goto bad;
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43 if((sz = allocuvm(pgdir, sz, ph.vaddr + ph.memsz)) == 0)
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44 goto bad;
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45 if(loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0)
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46 goto bad;
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47 }
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48 iunlockput(ip);
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49 ip = 0;
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50
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51 // Allocate two pages at the next page boundary.
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52 // Make the first inaccessible. Use the second as the user stack.
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53 sz = PGROUNDUP(sz);
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54 if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)
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55 goto bad;
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56 clearpteu(pgdir, (char*)(sz - 2*PGSIZE));
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57 sp = sz;
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58 // Push argument strings, prepare rest of stack in ustack.
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59 for(argc = 0; argv[argc]; argc++) {
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60 if(argc >= MAXARG)
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61 goto bad;
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62 sp = (sp - (strlen(argv[argc]) + 1)) & ~3;
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63 if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0)
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64 goto bad;
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65 ustack[3+argc] = sp;
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66 }
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67 ustack[3+argc] = 0;
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68
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69 //cprintf("Exec is called argc=%d sz=%x\n", argc, sz);
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70
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71 ustack[0] = 0xffffffff; // fake return PC
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72 ustack[1] = argc;
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73 ustack[2] = sp - (argc+1)*4; // argv pointer
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74
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75 sp -= (3+argc+1) * 4;
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76 if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)
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77 goto bad;
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78
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79 // Save program name for debugging.
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80 /* for(last=s=path; *s; s++)
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81 if(*s == '/')
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82 last = s+1;*/
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83 last = argv[0];
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84 safestrcpy(curr_proc->name, last, sizeof(curr_proc->name));
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85
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86 // Commit to the user image.
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87 oldpgdir = curr_proc->pgdir;
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88 curr_proc->pgdir = pgdir;
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89 curr_proc->sz = sz;
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90 curr_proc->tf->pc = elf.entry; // main
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91 curr_proc->tf->sp = sp;
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92 curr_proc->tf->r0 = ustack[1];
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93 curr_proc->tf->r1 = ustack[2];
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94 switchuvm(curr_proc);
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95 freevm(oldpgdir);
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96 return 0;
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97
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98 bad:
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99 if(pgdir)
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100 freevm(pgdir);
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101 if(ip)
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102 iunlockput(ip);
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103 return -1;
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104 }
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