Mercurial > hg > Members > mitsuki > xv6_rpi2_port

comparison source/exec.c @ 0:ed10291ff195

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author mir3636
date Sun, 06 Jan 2019 19:27:03 +0900
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-1:000000000000 0:ed10291ff195
1 #include "types.h"
2 #include "param.h"
3 #include "memlayout.h"
4 #include "mmu.h"
5 #include "proc.h"
6 #include "defs.h"
7 #include "arm.h"
8 #include "elf.h"
9
10 int
11 exec(char *path, char **argv)
12 {
13 char *last;
14 int i, off;
15 uint argc, sz, sp, ustack[3+MAXARG+1];
16 struct elfhdr elf;
17 struct inode *ip;
18 struct proghdr ph;
19 pde_t *pgdir, *oldpgdir;
20
21 if((ip = namei(path)) == 0)
22 return -1;
23 ilock(ip);
24 pgdir = 0;
25
26 // Check ELF header
27 if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
28 goto bad;
29 if(elf.magic != ELF_MAGIC)
30 goto bad;
31
32 if((pgdir = setupkvm()) == 0)
33 goto bad;
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.vaddr + ph.memsz)) == 0)
44 goto bad;
45 if(loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0)
46 goto bad;
47 }
48 iunlockput(ip);
49 ip = 0;
50
51 // Allocate two pages at the next page boundary.
52 // Make the first inaccessible. Use the second as the user stack.
53 sz = PGROUNDUP(sz);
54 if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)
55 goto bad;
56 clearpteu(pgdir, (char*)(sz - 2*PGSIZE));
57 sp = sz;
58 // Push argument strings, prepare rest of stack in ustack.
59 for(argc = 0; argv[argc]; argc++) {
60 if(argc >= MAXARG)
61 goto bad;
62 sp = (sp - (strlen(argv[argc]) + 1)) & ~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 //cprintf("Exec is called argc=%d sz=%x\n", argc, sz);
70
71 ustack[0] = 0xffffffff; // fake return PC
72 ustack[1] = argc;
73 ustack[2] = sp - (argc+1)*4; // argv pointer
74
75 sp -= (3+argc+1) * 4;
76 if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)
77 goto bad;
78
79 // Save program name for debugging.
80 /* for(last=s=path; *s; s++)
81 if(*s == '/')
82 last = s+1;*/
83 last = argv[0];
84 safestrcpy(curr_proc->name, last, sizeof(curr_proc->name));
85
86 // Commit to the user image.
87 oldpgdir = curr_proc->pgdir;
88 curr_proc->pgdir = pgdir;
89 curr_proc->sz = sz;
90 curr_proc->tf->pc = elf.entry; // main
91 curr_proc->tf->sp = sp;
92 curr_proc->tf->r0 = ustack[1];
93 curr_proc->tf->r1 = ustack[2];
94 switchuvm(curr_proc);
95 freevm(oldpgdir);
96 return 0;
97
98 bad:
99 if(pgdir)
100 freevm(pgdir);
101 if(ip)
102 iunlockput(ip);
103 return -1;
104 }