\u30c6\u30ad\u30b9\u30c8\u306e27\u301c29\u30da\u30fc\u30b8<\/p>\n
\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u304c\u5230\u9054\u3057\u305f\u3068\u304d\uff08\u7b2c2\u7ae0\u3067\u3069\u3046\u3084\u3063\u3066\u305d\u308c\u304c\u8d77\u304d\u308b\u304b\u8aac\u660e\u3059\u308b\uff09\u3001syscall\u306fsyscall\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3057sys_exec\u3092\u547c\u3073\u51fa\u3059\u3002
\nsys_exec\u306f\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306e\u5f15\u6570\u3092\u89e3\u91c8\u3057\u3001exec\u3092\u547c\u3073\u51fa\u3059\u3002<\/p>\n
syscall.c\u306esyscall\u95a2\u6570\u3068\u30c6\u30fc\u30d6\u30eb<\/p>\n
static int (*syscalls[])(void) = {\n[SYS_fork] sys_fork,\n[SYS_exit] sys_exit,\n[SYS_wait] sys_wait,\n[SYS_pipe] sys_pipe,\n[SYS_read] sys_read,\n[SYS_kill] sys_kill,\n[SYS_exec] sys_exec,\n[SYS_fstat] sys_fstat,\n[SYS_chdir] sys_chdir,\n[SYS_dup] sys_dup,\n[SYS_getpid] sys_getpid,\n[SYS_sbrk] sys_sbrk,\n[SYS_sleep] sys_sleep,\n[SYS_uptime] sys_uptime,\n[SYS_open] sys_open,\n[SYS_write] sys_write,\n[SYS_mknod] sys_mknod,\n[SYS_unlink] sys_unlink,\n[SYS_link] sys_link,\n[SYS_mkdir] sys_mkdir,\n[SYS_close] sys_close,\n};\n\nvoid\nsyscall(void)\n{\n int num;\n\n num = proc->tf->eax;\n if(num >= 0 && num < SYS_open && syscalls[num]) {\n proc->tf->eax = syscalls[num]();\n } else if (num >= SYS_open && num < NELEM(syscalls) && syscalls[num]) {\n proc->tf->eax = syscalls[num]();\n } else {\n cprintf("%d %s: unknown sys call %d\\n",\n proc->pid, proc->name, num);\n proc->tf->eax = -1;\n }\n}<\/pre>\nsysfile.c\u306esys_exec\u95a2\u6570<\/p>\n
int\nsys_exec(void)\n{\n char *path, *argv[MAXARG];\n int i;\n uint uargv, uarg;\n\n if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0){\n return -1;\n }\n memset(argv, 0, sizeof(argv));\n for(i=0;; i++){\n if(i >= NELEM(argv))\n return -1;\n if(fetchint(proc, uargv+4*i, (int*)&uarg) < 0)\n return -1;\n if(uarg == 0){\n argv[i] = 0;\n break;\n }\n if(fetchstr(proc, uarg, &argv[i]) < 0)\n return -1;\n }\n return exec(path, argv);\n}[\/sourcecode]\n\nexec\u306fnamei\u3092\u4f7f\u3063\u3066path\u3067\u540d\u4ed8\u3051\u3089\u308c\u305f\u30d0\u30a4\u30ca\u30ea\u3092\u958b\u304d\uff08\u305d\u306e\u8fba\u306e\u8a73\u7d30\u306f\u7b2c5\u7ae0\u3067\u8aac\u660e\u3059\u308b\uff09\u3001\u305d\u3057\u3066\u305d\u306eELF\u30d8\u30c3\u30c0\u3092\u8aad\u3080\u3002\nxv6\u306e\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306f\u3001\u5e83\u304f\u4f7f\u308f\u308c\u3066\u308bELF\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3067\u8868\u73fe\u3055\u308c\u3066\u3044\u3066\u3001\u305d\u308c\u306felf.h\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u3002\nELF\u30d0\u30a4\u30ca\u30ea\u306f\u3001ELF\u30d8\u30c3\u30c0\uff08elfhdr\u69cb\u9020\u4f53\uff09\u304b\u3089\u6210\u308a\u3001\u305d\u306e\u5f8c\u306b\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306e\u9023\u306a\u308a\uff08proghdr\u69cb\u9020\u4f53\uff09\u304c\u7d9a\u304f\u3002\n\u3069\u306eproghdr\u3082\u3001\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u307e\u308c\u308b\u3079\u304d\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u4e00\u90e8\u3092\u8a18\u8ff0\u3057\u3066\u3044\u308b\u3002\nxv6\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u306f\u4e00\u3064\u3060\u3051\u3057\u304b\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u3092\u6301\u305f\u306a\u3044\u304c\u3001\u4ed6\u306e\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u547d\u4ee4\u3068\u30c7\u30fc\u30bf\u306e\u305f\u3081\u306e\u5206\u5272\u3055\u308c\u305f\u4e00\u90e8\u3092\u6301\u3064\u3060\u308d\u3046\u3002\n\nexec.c\u306e\u5168\u3066\n[sourcecode language="c"]#include "types.h"\n#include "param.h"\n#include "memlayout.h"\n#include "mmu.h"\n#include "proc.h"\n#include "defs.h"\n#include "x86.h"\n#include "elf.h"\n\nint\nexec(char *path, char **argv)\n{\n char *s, *last;\n int i, off;\n uint argc, sz, sp, ustack[3+MAXARG+1];\n struct elfhdr elf;\n struct inode *ip;\n struct proghdr ph;\n pde_t *pgdir, *oldpgdir;\n\n if((ip = namei(path)) == 0)\n return -1;\n ilock(ip);\n pgdir = 0;\n\n \/\/ Check ELF header\n if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))\n goto bad;\n if(elf.magic != ELF_MAGIC)\n goto bad;\n\n if((pgdir = setupkvm(kalloc)) == 0)\n goto bad;\n\n \/\/ Load program into memory.\n sz = 0;\n for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){\n if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))\n goto bad;\n if(ph.type != ELF_PROG_LOAD)\n continue;\n if(ph.memsz < ph.filesz)\n goto bad;\n if((sz = allocuvm(pgdir, sz, ph.vaddr + ph.memsz)) == 0)\n goto bad;\n if(loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0)\n goto bad;\n }\n iunlockput(ip);\n ip = 0;\n\n \/\/ Allocate two pages at the next page boundary.\n \/\/ Make the first inaccessible. Use the second as the user stack.\n sz = PGROUNDUP(sz);\n if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)\n goto bad;\n clearpteu(pgdir, (char*)(sz - 2*PGSIZE));\n sp = sz;\n\n \/\/ Push argument strings, prepare rest of stack in ustack.\n for(argc = 0; argv[argc]; argc++) {\n if(argc >= MAXARG)\n goto bad;\n sp = (sp - (strlen(argv[argc]) + 1)) & ~3;\n if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0)\n goto bad;\n ustack[3+argc] = sp;\n }\n ustack[3+argc] = 0;\n\n ustack[0] = 0xffffffff; \/\/ fake return PC\n ustack[1] = argc;\n ustack[2] = sp - (argc+1)*4; \/\/ argv pointer\n\n sp -= (3+argc+1) * 4;\n if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)\n goto bad;\n\n \/\/ Save program name for debugging.\n for(last=s=path; *s; s++)\n if(*s == '\/')\n last = s+1;\n safestrcpy(proc->name, last, sizeof(proc->name));\n\n \/\/ Commit to the user image.\n oldpgdir = proc->pgdir;\n proc->pgdir = pgdir;\n proc->sz = sz;\n proc->tf->eip = elf.entry; \/\/ main\n proc->tf->esp = sp;\n switchuvm(proc);\n freevm(oldpgdir);\n return 0;\n\n bad:\n if(pgdir)\n freevm(pgdir);\n if(ip)\n iunlockput(ip);\n return -1;\n}<\/pre>\nelf.h\u306e\u5168\u3066<\/p>\n
\/\/ Format of an ELF executable file\n\n#define ELF_MAGIC 0x464C457FU \/\/ \"\\x7FELF\" in little endian\n\n\/\/ File header\nstruct elfhdr {\n uint magic; \/\/ must equal ELF_MAGIC\n uchar elf[12];\n ushort type;\n ushort machine;\n uint version;\n uint entry;\n uint phoff;\n uint shoff;\n uint flags;\n ushort ehsize;\n ushort phentsize;\n ushort phnum;\n ushort shentsize;\n ushort shnum;\n ushort shstrndx;\n};\n\n\/\/ Program section header\nstruct proghdr {\n uint type;\n uint off;\n uint vaddr;\n uint paddr;\n uint filesz;\n uint memsz;\n uint flags;\n uint align;\n};\n\n\/\/ Values for Proghdr type\n#define ELF_PROG_LOAD 1\n\n\/\/ Flag bits for Proghdr flags\n#define ELF_PROG_FLAG_EXEC 1\n#define ELF_PROG_FLAG_WRITE 2\n#define ELF_PROG_FLAG_READ 4<\/pre>\n\u6700\u521d\u306e\u4e00\u6b69\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u304cELF\u30d0\u30a4\u30ca\u30ea\u3092\u542b\u3080\u304b\u3069\u3046\u304b\u306e\u7c21\u6613\u7684\u306a\u30c1\u30a7\u30c3\u30af\u3067\u3042\u308b\u3002
\nELF\u30d0\u30a4\u30ca\u30ea\u306f\u30014\u30d0\u30a4\u30c8\u306e\u30de\u30b8\u30c3\u30af\u30ca\u30f3\u30d0\u30fc0x7F, ‘E’, ‘L’, ‘F’\uff08elf.h\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u308bELF_MAGIC\uff09\u3067\u59cb\u307e\u308b\u3002
\n\u3082\u3057ELF\u30d8\u30c3\u30c0\u304c\u6b63\u3057\u3044\u30de\u30b8\u30c3\u30af\u30ca\u30f3\u30d0\u30fc\u3092\u6301\u3064\u306a\u3089\u3001exec\u306f\u305d\u306e\u30d0\u30a4\u30ca\u30ea\u3092\u6b63\u3057\u3044\u3068\u3044\u3046\u4e8b\u306b\u3059\u308b\u3002<\/p>\n
exec\u304c\u3001setupkvm\u3067\u30e6\u30fc\u30b6\u7528\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u7121\u3057\u3067\u65b0\u3057\u3044\u30da\u30fc\u30b8\u30c6\u30fc\u30d6\u30eb\u3092\u5272\u308a\u5f53\u3066\u308b\u3068\u3001allocuvm\u3067\u305d\u308c\u305e\u308c\u306eELF\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u305f\u3081\u306e\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u3001\u305d\u3057\u3066loaduvm\u3092\u4f7f\u3063\u3066\u305d\u308c\u305e\u308c\u306e\u30bb\u30b0\u30e1\u30f3\u30c8\u3092\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u3080\u3002
\n\/init\u306e\u305f\u3081\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306f\u6b21\u306e\u3088\u3046\u306b\u306a\u308b\u3002<\/p>\n
# objdump -p _init\n_init: file format elf32-i386\nProgram Header:\nLOAD off 0x00000054 vaddr 0x00000000 paddr 0x00000000 align 2**2\n filesz 0x000008c0 memsz 0x000008cc flags rwx<\/pre>\nallocuvm\u306f\u8981\u6c42\u3055\u308c\u305f\u4eee\u60f3\u30a2\u30c9\u30ec\u30b9\u304cKERNBASE\u672a\u6e80\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u3002
\nloaduvm\u306fELF\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u30da\u30fc\u30b8\u3092\u66f8\u304d\u8fbc\u3080\u305f\u3081\u306e\u5272\u308a\u5f53\u3066\u6e08\u307f\u7269\u7406\u30e1\u30e2\u30ea\u3092walkpgdir\u3092\u4f7f\u3063\u3066\u63a2\u3057\u3001readi\u3092\u4f7f\u3063\u3066\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u3080\u3002<\/p>\n
vm.c\u306eallocuvm\u3068loaduvm<\/p>\n
\/\/ Load a program segment into pgdir. addr must be page-aligned\n\/\/ and the pages from addr to addr+sz must already be mapped.\nint\nloaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)\n{\n uint i, pa, n;\n pte_t *pte;\n\n if((uint) addr % PGSIZE != 0)\n panic("loaduvm: addr must be page aligned");\n for(i = 0; i < sz; i += PGSIZE){\n if((pte = walkpgdir(pgdir, addr+i, 0)) == 0)\n panic("loaduvm: address should exist");\n pa = PTE_ADDR(*pte);\n if(sz - i < PGSIZE)\n n = sz - i;\n else\n n = PGSIZE;\n if(readi(ip, p2v(pa), offset+i, n) != n)\n return -1;\n }\n return 0;\n}\n\n\/\/ Allocate page tables and physical memory to grow process from oldsz to\n\/\/ newsz, which need not be page aligned. Returns new size or 0 on error.\nint\nallocuvm(pde_t *pgdir, uint oldsz, uint newsz)\n{\n char *mem;\n uint a;\n\n if(newsz >= KERNBASE)\n return 0;\n if(newsz < oldsz)\n return oldsz;\n\n a = PGROUNDUP(oldsz);\n for(; a < newsz; a += PGSIZE){\n mem = kalloc();\n if(mem == 0){\n cprintf("allocuvm out of memory\\n");\n deallocuvm(pgdir, newsz, oldsz);\n return 0;\n }\n memset(mem, 0, PGSIZE);\n mappages(pgdir, (char*)a, PGSIZE, v2p(mem), PTE_W|PTE_U, kalloc);\n }\n return newsz;\n}[\/sourcecode]\n\n\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306efilesz\u306fmemsz\u3088\u308a\u591a\u5206\u5c0f\u3055\u304f\u306a\u308a\u3001\u305d\u306e\u5dee\u306f\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u307e\u308c\u308b\u4ee3\u308f\u308a\u306b\u30bc\u30ed\u3067\u57cb\u3081\u3089\u308c\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\uff08C\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u5909\u6570\u306e\u305f\u3081\uff09\u3002\n\/init\u306e\u5834\u5408\u3001filesz\u306f2240\u30d0\u30a4\u30c8\u3067memsz\u306f2252\u30d0\u30a4\u30c8\u3067\u3042\u308a\u3001allocuvm\u306f2252\u30d0\u30a4\u30c8\u3092\u4fdd\u6301\u3059\u308b\u306e\u306b\u5341\u5206\u306a\u7269\u7406\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u304c\u3001\/init\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u307e\u308c\u308b\u306e\u306f2240\u30d0\u30a4\u30c8\u306e\u307f\u3067\u3042\u308b\u3002\n\uff08filesz\u3084memsz\u3068\u3044\u3046\u306e\u306fELF\u30d0\u30a4\u30ca\u30ea\u306e\u4e2d\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u3054\u3068\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u308b\u5024\uff09\n\n\u305d\u3057\u305f\u3089\u3001exec\u306f1\u30da\u30fc\u30b8\u5206\u3060\u3051\u30e6\u30fc\u30b6\u30b9\u30bf\u30c3\u30af\u3092\u5272\u308a\u5f53\u3066\u521d\u671f\u5316\u3059\u308b\u3002\n\u305d\u3057\u3066\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c1\u30da\u30fc\u30b8\u3088\u308a\u591a\u304f\u4f7f\u304a\u3046\u3068\u3057\u305f\u3089\u5931\u6557\u3059\u308b\u3088\u3046\u306b\u3059\u308b\u305f\u3081\u306b\u3001\u305d\u306e\u30b9\u30bf\u30c3\u30af\u7528\u306e\u30da\u30fc\u30b8\u306e\u4e0b\u4f4d\u306b\u30a2\u30af\u30bb\u30b9\u51fa\u6765\u306a\u3044\u30da\u30fc\u30b8\u3092\u4e00\u3064\u914d\u7f6e\u3059\u308b\u3002\n\u3053\u306e\u30a2\u30af\u30bb\u30b9\u51fa\u6765\u306a\u3044\u30da\u30fc\u30b8\u306f\u3001\u9577\u3059\u304e\u308b\u5f15\u6570\u306bexec\u304c\u5bfe\u51e6\u3059\u308b\u3053\u3068\u3082\u307e\u305f\u53ef\u80fd\u306b\u3059\u308b\u3002\n\u305d\u3046\u3044\u3046\u3068\u304d\uff08\u9577\u3059\u304e\u308b\u5f15\u6570\u304c\u6e21\u3055\u308c\u305f\u3068\u304d\uff09\u306f\u3001exec\u304c\u5f15\u6570\u3092\u30b9\u30bf\u30c3\u30af\u306b\u30b3\u30d4\u30fc\u3059\u308b\u305f\u3081\u306b\u4f7f\u3063\u3066\u308bcopyout\u95a2\u6570\u304c\u3001\u30b3\u30d4\u30fc\u5148\u306e\u30da\u30fc\u30b8\u304c\u30a2\u30af\u30bb\u30b9\u4e0d\u80fd\u3067\u3042\u308b\u4e8b\u3092\u691c\u77e5\u3057\u3001-1\u304c\u8fd4\u308b\u3002\n\nexec\u306f\u3001\u4e00\u5ea6\u306b\u4e00\u3064\u305a\u3064\u30b9\u30bf\u30c3\u30af\u306e\u30c8\u30c3\u30d7\u306b\u5f15\u6570\u306e\u6587\u5b57\u5217\u3092\u30b3\u30d4\u30fc\u3057\u3001\u305d\u3053\u306b\u5bfe\u3059\u308b\u30dd\u30a4\u30f3\u30bf\u3092ustack\u306b\u8a18\u9332\u3059\u308b\u3002\n\u305d\u3057\u3066\u3001main\u306b\u6e21\u3055\u308c\u308bargv\u306e\u30ea\u30b9\u30c8\u306b\u306a\u308b\u3067\u3042\u308d\u3046\u3082\u306e\u306e\u6700\u5f8c\u306b\u30cc\u30eb\u30dd\u30a4\u30f3\u30bf\u3092\u7f6e\u304f\u3002\n\u6700\u521d\u306e3\u3064\u306eustack\u306e\u9805\u76ee\u306f\u3001argv\u3068argc\u306e\u30dd\u30a4\u30f3\u30bf\u3068PC\u3078\u306e\u507d\u306e\u30ea\u30bf\u30fc\u30f3\uff08fake return PC\uff09\u3067\u3042\u308b\u3002\n\n\u65b0\u3057\u3044\u30e1\u30e2\u30ea\u30a4\u30fc\u76ee\u5730\u3092\u7528\u610f\u3057\u3066\u3044\u308b\u9593\u3001\u3082\u3057exec\u304c\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u7570\u5e38\u306e\u3088\u3046\u306a\u30a8\u30e9\u30fc\u3092\u691c\u51fa\u3057\u305f\u3089\u3001bad\u30e9\u30d9\u30eb\u306b\u30b8\u30e3\u30f3\u30d7\u3057\u3001\u305d\u306e\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3057\u3001-1\u3092\u8fd4\u3059\u3002\nexec\u306f\u3001\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3059\u308b\u306e\u3092\u305d\u308c\u304c\u78ba\u5b9f\u306b\u306a\u308b\u307e\u3067\u5f85\u305f\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002\n\u3082\u3057\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u306e\u89e3\u653e\u304c\u5b8c\u4e86\u3057\u305f\u3089\u3001-1\u3092\u8fd4\u3059\u4e8b\u306f\u306a\u3044\u3002\nexec\u306b\u304a\u3051\u308b\u30a8\u30e9\u30fc\u306f\u3001\u30a4\u30e1\u30fc\u30b8\u306e\u751f\u6210\u3092\u3057\u3066\u308b\u9593\u3060\u3051\u8d77\u304d\u308b\u3002\n\u4e00\u5ea6\u30a4\u30e1\u30fc\u30b8\u304c\u5b8c\u4e86\u8a2d\u697d\u3001exec\u306f\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u30a4\u30f3\u30b9\u30fc\u30eb\u3057\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3059\u308b\u3053\u3068\u304c\u51fa\u6765\u308b\u3002\n\uff08exec\u95a2\u6570\u306ebad\u30e9\u30d9\u30eb\u306e\u76f4\u524d\u306e\u90e8\u5206\u3002switchuvm\u3068freevm\uff09\n\u6700\u5f8c\u306b\u3001exec\u306f0\u3092\u8fd4\u3059\u3002\n\u6210\u529f\u3060\uff01\n\n\u3053\u308c\u3067\u3001initcode\u306f\u5b8c\u4e86\u3057\u305f\u3002\nexec\u306f\u3001\u305d\u308c\u3092\/init\u30d0\u30a4\u30ca\u30ea\u3067\u7f6e\u304d\u63db\u3048\u3001loaded out of the file system.\uff08\u3053\u3053\u5206\u304b\u3089\u306a\u3044\uff09\ninit\u306f\u3001\u5fc5\u8981\u306a\u3089\u65b0\u3057\u3044\u30b3\u30f3\u30bd\u30fc\u30eb\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3092\u751f\u6210\u3057\u3001\u305d\u3057\u3066\u305d\u308c\u3092\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf0,1,2\u3068\u3057\u3066\u958b\u304f\u3002\n\u305d\u3057\u3066\u30eb\u30fc\u30d7\u3057\u3001\u30b3\u30f3\u30bd\u30fc\u30eb\u30b7\u30a7\u30eb\u3092\u958b\u59cb\u3057\u3001\u30b7\u30a7\u30eb\u304c\u7d42\u4e86\u3059\u308b\u307e\u3067\u89aa\u306e\u306a\u3044\u30be\u30f3\u30d3\u3092\u5236\u5fa1\u3057\u3001\u7e70\u308a\u8fd4\u3059\u3002\n\u3053\u308c\u3067\u30b7\u30b9\u30c6\u30e0\u306f\u8d77\u52d5\u3092\u5b8c\u4e86\u3057\u305f\u4e8b\u306b\u306a\u308b\u3002\n\ninit.c\u306e\u5168\u3066\n[sourcecode language="c"]\/\/ init: The initial user-level program\n\n#include "types.h"\n#include "stat.h"\n#include "user.h"\n#include "fcntl.h"\n\nchar *argv[] = { "sh", 0 };\n\nint\nmain(void)\n{\n int pid, wpid;\n\n if(open("console", O_RDWR) < 0){\n mknod("console", 1, 1);\n open("console", O_RDWR);\n }\n dup(0); \/\/ stdout\n dup(0); \/\/ stderr\n\n for(;;){\n printf(1, "init: starting sh\\n");\n pid = fork();\n if(pid < 0){\n printf(1, "init: fork failed\\n");\n exit();\n }\n if(pid == 0){\n exec("sh", argv);\n printf(1, "init: exec sh failed\\n");\n exit();\n }\n while((wpid=wait()) >= 0 && wpid != pid)\n printf(1, "zombie!\\n");\n }\n}<\/pre>\n\u30b7\u30b9\u30c6\u30e0\u304c\u8d77\u52d5\u5b8c\u4e86\u3057\u305f\u3068\u306f\u3044\u3048\u3001xv6\u306e\u91cd\u8981\u306a\u30b5\u30d6\u30b7\u30b9\u30c6\u30e0\u3092\u3044\u304f\u3064\u304b\u98db\u3070\u3057\u3066\u8aac\u660e\u3057\u3066\u304d\u305f\u3002
\n\u6b21\u306e\u7ae0\u3067\u306f\u3001int $T_SYSCALL\u306b\u3088\u3063\u3066\u5f15\u304d\u8d77\u3053\u3055\u308c\u308b\u5272\u308a\u8fbc\u307f\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u5236\u5fa1\u3055\u305b\u308b\u305f\u3081\u306bx86\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u3092\u3069\u3046\u3084\u3063\u3066xv6\u304c\u8a2d\u5b9a\u3059\u308b\u304b\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002
\n\u6b8b\u308a\u306e\u7ae0\u3067\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u7ba1\u7406\u3068\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
exec\u4e2d\u5fc3\u306e\u8a71\u3067\u3059\u3002
\n\u6700\u521d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u8d77\u52d5\u306b\u3082exec\u3092\u4f7f\u3046\u3093\u3067\u3059\u306d\u3002
\n\u3082\u3061\u308d\u3093\u3053\u308c\u307e\u3067\u306e\u7bc0\u3067\u3001\u6700\u521d\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u3044\u3048\u3069\u306a\u308b\u3079\u304f\u901a\u5e38\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u540c\u3058\u3088\u3046\u306b\u6a19\u6e96\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u5229\u7528\u3057\u3066\u3044\u308b\u3068\u3044\u3046\u611f\u3058\u306e\u8aac\u660e\u304c\u3042\u3063\u305f\u306e\u3067\u305d\u3046\u9a5a\u304f\u3088\u3046\u306a\u3053\u3068\u3067\u306f\u306a\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n
\u9014\u4e2d\u306e\u8aac\u660e\u3067\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u306e\u89e3\u653e\u306e\u90e8\u5206\u306b\u4e00\u77ac\u304a\u3084\uff1f\u3068\u306a\u308a\u307e\u3057\u305f\u304c\u3001\u305d\u3082\u305d\u3082exec\u306f\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u90e8\u5206\u306a\u3069\u3092\u6b8b\u3057\u3066\u5143\u306e\u30a4\u30e1\u30fc\u30b8\u3092\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3067\u7f6e\u304d\u63db\u3048\u308b\u306e\u304c\u901a\u5e38\u306e\u52d5\u4f5c\u3067\u3059\u3002
\n\uff08\u306a\u306e\u3067\u901a\u5e38\u4f7f\u3046\u3068\u304d\u306f\u305d\u306e\u524d\u306bfork\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3057\u305f\u306d\uff09
\n\u89e3\u653e\u306e\u8a71\u304c\u5165\u3063\u3066\u304f\u308b\u306e\u3082\u5f53\u7136\u3067\u3059\u306d\u3002<\/p>\n
\u3053\u306e\u7ae0\u306e\u8aac\u660e\u90e8\u5206\u306f\u7d42\u308f\u308a\u3067\u3059\u304c\u3001\u3042\u3068Real world\u3068\u3044\u3046\u7bc0\u3068Exercises\u3068\u3044\u3046\u7bc0\u304c\u6b8b\u3063\u3066\u307e\u3059\u3002
\n\u4e00\u5fdc\u5168\u90e8\u3084\u308b\u3064\u3082\u308a\u3067\u3059\u304cExercises\u306f\u3001\u3084\u308d\u3046\u3068\u601d\u3048\u3070\u3044\u304f\u3089\u3067\u3082\u6398\u308a\u4e0b\u3052\u308c\u305d\u3046\u306a\u6c17\u304c\u3059\u308b\u306e\u3067\u3001\u30b5\u30e9\u30c3\u3068\u7a0b\u5ea6\u306b\u3057\u3068\u304f\u3064\u3082\u308a\u3067\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u30c6\u30ad\u30b9\u30c8\u306e27\u301c29\u30da\u30fc\u30b8<\/p>\n
\u672c\u6587<\/h3>\n
\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u304c\u5230\u9054\u3057\u305f\u3068\u304d\uff08\u7b2c2\u7ae0\u3067\u3069\u3046\u3084\u3063\u3066\u305d\u308c\u304c\u8d77\u304d\u308b\u304b\u8aac\u660e\u3059\u308b\uff09\u3001syscall\u306fsyscall\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3057sys_exec\u3092\u547c\u3073\u51fa\u3059\u3002
\nsys_exec\u306f\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306e\u5f15\u6570\u3092\u89e3\u91c8\u3057\u3001exec\u3092\u547c\u3073\u51fa\u3059\u3002<\/p>\n
syscall.c\u306esyscall\u95a2\u6570\u3068\u30c6\u30fc\u30d6\u30eb<\/p>\n
static int (*syscalls[])(void) = {\n[SYS_fork] sys_fork,\n[SYS_exit] sys_exit,\n[SYS_wait] sys_wait,\n[SYS_pipe] sys_pipe,\n[SYS_read] sys_read,\n[SYS_kill] sys_kill,\n[SYS_exec] sys_exec,\n[SYS_fstat] sys_fstat,\n[SYS_chdir] sys_chdir,\n[SYS_dup] sys_dup,\n[SYS_getpid] sys_getpid,\n[SYS_sbrk] sys_sbrk,\n[SYS_sleep] sys_sleep,\n[SYS_uptime] sys_uptime,\n[SYS_open] sys_open,\n[SYS_write] sys_write,\n[SYS_mknod] sys_mknod,\n[SYS_unlink] sys_unlink,\n[SYS_link] sys_link,\n[SYS_mkdir] sys_mkdir,\n[SYS_close] sys_close,\n};\n\nvoid\nsyscall(void)\n{\n int num;\n\n num = proc->tf->eax;\n if(num >= 0 && num < SYS_open && syscalls[num]) {\n proc->tf->eax = syscalls[num]();\n } else if (num >= SYS_open && num < NELEM(syscalls) && syscalls[num]) {\n proc->tf->eax = syscalls[num]();\n } else {\n cprintf("%d %s: unknown sys call %d\\n",\n proc->pid, proc->name, num);\n proc->tf->eax = -1;\n }\n}<\/pre>\nsysfile.c\u306esys_exec\u95a2\u6570<\/p>\n
int\nsys_exec(void)\n{\n char *path, *argv[MAXARG];\n int i;\n uint uargv, uarg;\n\n if(argstr(0, &path) < 0 || argint(1, (int*)&uargv) < 0){\n return -1;\n }\n memset(argv, 0, sizeof(argv));\n for(i=0;; i++){\n if(i >= NELEM(argv))\n return -1;\n if(fetchint(proc, uargv+4*i, (int*)&uarg) < 0)\n return -1;\n if(uarg == 0){\n argv[i] = 0;\n break;\n }\n if(fetchstr(proc, uarg, &argv[i]) < 0)\n return -1;\n }\n return exec(path, argv);\n}[\/sourcecode]\n\nexec\u306fnamei\u3092\u4f7f\u3063\u3066path\u3067\u540d\u4ed8\u3051\u3089\u308c\u305f\u30d0\u30a4\u30ca\u30ea\u3092\u958b\u304d\uff08\u305d\u306e\u8fba\u306e\u8a73\u7d30\u306f\u7b2c5\u7ae0\u3067\u8aac\u660e\u3059\u308b\uff09\u3001\u305d\u3057\u3066\u305d\u306eELF\u30d8\u30c3\u30c0\u3092\u8aad\u3080\u3002\nxv6\u306e\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306f\u3001\u5e83\u304f\u4f7f\u308f\u308c\u3066\u308bELF\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u3067\u8868\u73fe\u3055\u308c\u3066\u3044\u3066\u3001\u305d\u308c\u306felf.h\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u3002\nELF\u30d0\u30a4\u30ca\u30ea\u306f\u3001ELF\u30d8\u30c3\u30c0\uff08elfhdr\u69cb\u9020\u4f53\uff09\u304b\u3089\u6210\u308a\u3001\u305d\u306e\u5f8c\u306b\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306e\u9023\u306a\u308a\uff08proghdr\u69cb\u9020\u4f53\uff09\u304c\u7d9a\u304f\u3002\n\u3069\u306eproghdr\u3082\u3001\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u307e\u308c\u308b\u3079\u304d\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u4e00\u90e8\u3092\u8a18\u8ff0\u3057\u3066\u3044\u308b\u3002\nxv6\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u306f\u4e00\u3064\u3060\u3051\u3057\u304b\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u3092\u6301\u305f\u306a\u3044\u304c\u3001\u4ed6\u306e\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u547d\u4ee4\u3068\u30c7\u30fc\u30bf\u306e\u305f\u3081\u306e\u5206\u5272\u3055\u308c\u305f\u4e00\u90e8\u3092\u6301\u3064\u3060\u308d\u3046\u3002\n\nexec.c\u306e\u5168\u3066\n[sourcecode language="c"]#include "types.h"\n#include "param.h"\n#include "memlayout.h"\n#include "mmu.h"\n#include "proc.h"\n#include "defs.h"\n#include "x86.h"\n#include "elf.h"\n\nint\nexec(char *path, char **argv)\n{\n char *s, *last;\n int i, off;\n uint argc, sz, sp, ustack[3+MAXARG+1];\n struct elfhdr elf;\n struct inode *ip;\n struct proghdr ph;\n pde_t *pgdir, *oldpgdir;\n\n if((ip = namei(path)) == 0)\n return -1;\n ilock(ip);\n pgdir = 0;\n\n \/\/ Check ELF header\n if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))\n goto bad;\n if(elf.magic != ELF_MAGIC)\n goto bad;\n\n if((pgdir = setupkvm(kalloc)) == 0)\n goto bad;\n\n \/\/ Load program into memory.\n sz = 0;\n for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){\n if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))\n goto bad;\n if(ph.type != ELF_PROG_LOAD)\n continue;\n if(ph.memsz < ph.filesz)\n goto bad;\n if((sz = allocuvm(pgdir, sz, ph.vaddr + ph.memsz)) == 0)\n goto bad;\n if(loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0)\n goto bad;\n }\n iunlockput(ip);\n ip = 0;\n\n \/\/ Allocate two pages at the next page boundary.\n \/\/ Make the first inaccessible. Use the second as the user stack.\n sz = PGROUNDUP(sz);\n if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)\n goto bad;\n clearpteu(pgdir, (char*)(sz - 2*PGSIZE));\n sp = sz;\n\n \/\/ Push argument strings, prepare rest of stack in ustack.\n for(argc = 0; argv[argc]; argc++) {\n if(argc >= MAXARG)\n goto bad;\n sp = (sp - (strlen(argv[argc]) + 1)) & ~3;\n if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0)\n goto bad;\n ustack[3+argc] = sp;\n }\n ustack[3+argc] = 0;\n\n ustack[0] = 0xffffffff; \/\/ fake return PC\n ustack[1] = argc;\n ustack[2] = sp - (argc+1)*4; \/\/ argv pointer\n\n sp -= (3+argc+1) * 4;\n if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)\n goto bad;\n\n \/\/ Save program name for debugging.\n for(last=s=path; *s; s++)\n if(*s == '\/')\n last = s+1;\n safestrcpy(proc->name, last, sizeof(proc->name));\n\n \/\/ Commit to the user image.\n oldpgdir = proc->pgdir;\n proc->pgdir = pgdir;\n proc->sz = sz;\n proc->tf->eip = elf.entry; \/\/ main\n proc->tf->esp = sp;\n switchuvm(proc);\n freevm(oldpgdir);\n return 0;\n\n bad:\n if(pgdir)\n freevm(pgdir);\n if(ip)\n iunlockput(ip);\n return -1;\n}<\/pre>\nelf.h\u306e\u5168\u3066<\/p>\n
\/\/ Format of an ELF executable file\n\n#define ELF_MAGIC 0x464C457FU \/\/ \"\\x7FELF\" in little endian\n\n\/\/ File header\nstruct elfhdr {\n uint magic; \/\/ must equal ELF_MAGIC\n uchar elf[12];\n ushort type;\n ushort machine;\n uint version;\n uint entry;\n uint phoff;\n uint shoff;\n uint flags;\n ushort ehsize;\n ushort phentsize;\n ushort phnum;\n ushort shentsize;\n ushort shnum;\n ushort shstrndx;\n};\n\n\/\/ Program section header\nstruct proghdr {\n uint type;\n uint off;\n uint vaddr;\n uint paddr;\n uint filesz;\n uint memsz;\n uint flags;\n uint align;\n};\n\n\/\/ Values for Proghdr type\n#define ELF_PROG_LOAD 1\n\n\/\/ Flag bits for Proghdr flags\n#define ELF_PROG_FLAG_EXEC 1\n#define ELF_PROG_FLAG_WRITE 2\n#define ELF_PROG_FLAG_READ 4<\/pre>\n\u6700\u521d\u306e\u4e00\u6b69\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u304cELF\u30d0\u30a4\u30ca\u30ea\u3092\u542b\u3080\u304b\u3069\u3046\u304b\u306e\u7c21\u6613\u7684\u306a\u30c1\u30a7\u30c3\u30af\u3067\u3042\u308b\u3002
\nELF\u30d0\u30a4\u30ca\u30ea\u306f\u30014\u30d0\u30a4\u30c8\u306e\u30de\u30b8\u30c3\u30af\u30ca\u30f3\u30d0\u30fc0x7F, ‘E’, ‘L’, ‘F’\uff08elf.h\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u308bELF_MAGIC\uff09\u3067\u59cb\u307e\u308b\u3002
\n\u3082\u3057ELF\u30d8\u30c3\u30c0\u304c\u6b63\u3057\u3044\u30de\u30b8\u30c3\u30af\u30ca\u30f3\u30d0\u30fc\u3092\u6301\u3064\u306a\u3089\u3001exec\u306f\u305d\u306e\u30d0\u30a4\u30ca\u30ea\u3092\u6b63\u3057\u3044\u3068\u3044\u3046\u4e8b\u306b\u3059\u308b\u3002<\/p>\n
exec\u304c\u3001setupkvm\u3067\u30e6\u30fc\u30b6\u7528\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u7121\u3057\u3067\u65b0\u3057\u3044\u30da\u30fc\u30b8\u30c6\u30fc\u30d6\u30eb\u3092\u5272\u308a\u5f53\u3066\u308b\u3068\u3001allocuvm\u3067\u305d\u308c\u305e\u308c\u306eELF\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u305f\u3081\u306e\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u3001\u305d\u3057\u3066loaduvm\u3092\u4f7f\u3063\u3066\u305d\u308c\u305e\u308c\u306e\u30bb\u30b0\u30e1\u30f3\u30c8\u3092\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u3080\u3002
\n\/init\u306e\u305f\u3081\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306f\u6b21\u306e\u3088\u3046\u306b\u306a\u308b\u3002<\/p>\n
# objdump -p _init\n_init: file format elf32-i386\nProgram Header:\nLOAD off 0x00000054 vaddr 0x00000000 paddr 0x00000000 align 2**2\n filesz 0x000008c0 memsz 0x000008cc flags rwx<\/pre>\nallocuvm\u306f\u8981\u6c42\u3055\u308c\u305f\u4eee\u60f3\u30a2\u30c9\u30ec\u30b9\u304cKERNBASE\u672a\u6e80\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u3002
\nloaduvm\u306fELF\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u30da\u30fc\u30b8\u3092\u66f8\u304d\u8fbc\u3080\u305f\u3081\u306e\u5272\u308a\u5f53\u3066\u6e08\u307f\u7269\u7406\u30e1\u30e2\u30ea\u3092walkpgdir\u3092\u4f7f\u3063\u3066\u63a2\u3057\u3001readi\u3092\u4f7f\u3063\u3066\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u3080\u3002<\/p>\n
vm.c\u306eallocuvm\u3068loaduvm<\/p>\n
\/\/ Load a program segment into pgdir. addr must be page-aligned\n\/\/ and the pages from addr to addr+sz must already be mapped.\nint\nloaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)\n{\n uint i, pa, n;\n pte_t *pte;\n\n if((uint) addr % PGSIZE != 0)\n panic("loaduvm: addr must be page aligned");\n for(i = 0; i < sz; i += PGSIZE){\n if((pte = walkpgdir(pgdir, addr+i, 0)) == 0)\n panic("loaduvm: address should exist");\n pa = PTE_ADDR(*pte);\n if(sz - i < PGSIZE)\n n = sz - i;\n else\n n = PGSIZE;\n if(readi(ip, p2v(pa), offset+i, n) != n)\n return -1;\n }\n return 0;\n}\n\n\/\/ Allocate page tables and physical memory to grow process from oldsz to\n\/\/ newsz, which need not be page aligned. Returns new size or 0 on error.\nint\nallocuvm(pde_t *pgdir, uint oldsz, uint newsz)\n{\n char *mem;\n uint a;\n\n if(newsz >= KERNBASE)\n return 0;\n if(newsz < oldsz)\n return oldsz;\n\n a = PGROUNDUP(oldsz);\n for(; a < newsz; a += PGSIZE){\n mem = kalloc();\n if(mem == 0){\n cprintf("allocuvm out of memory\\n");\n deallocuvm(pgdir, newsz, oldsz);\n return 0;\n }\n memset(mem, 0, PGSIZE);\n mappages(pgdir, (char*)a, PGSIZE, v2p(mem), PTE_W|PTE_U, kalloc);\n }\n return newsz;\n}[\/sourcecode]\n\n\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u306efilesz\u306fmemsz\u3088\u308a\u591a\u5206\u5c0f\u3055\u304f\u306a\u308a\u3001\u305d\u306e\u5dee\u306f\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u307e\u308c\u308b\u4ee3\u308f\u308a\u306b\u30bc\u30ed\u3067\u57cb\u3081\u3089\u308c\u3066\u3044\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\uff08C\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u5909\u6570\u306e\u305f\u3081\uff09\u3002\n\/init\u306e\u5834\u5408\u3001filesz\u306f2240\u30d0\u30a4\u30c8\u3067memsz\u306f2252\u30d0\u30a4\u30c8\u3067\u3042\u308a\u3001allocuvm\u306f2252\u30d0\u30a4\u30c8\u3092\u4fdd\u6301\u3059\u308b\u306e\u306b\u5341\u5206\u306a\u7269\u7406\u30e1\u30e2\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u304c\u3001\/init\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u8aad\u307f\u8fbc\u307e\u308c\u308b\u306e\u306f2240\u30d0\u30a4\u30c8\u306e\u307f\u3067\u3042\u308b\u3002\n\uff08filesz\u3084memsz\u3068\u3044\u3046\u306e\u306fELF\u30d0\u30a4\u30ca\u30ea\u306e\u4e2d\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30af\u30b7\u30e7\u30f3\u30d8\u30c3\u30c0\u3054\u3068\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u308b\u5024\uff09\n\n\u305d\u3057\u305f\u3089\u3001exec\u306f1\u30da\u30fc\u30b8\u5206\u3060\u3051\u30e6\u30fc\u30b6\u30b9\u30bf\u30c3\u30af\u3092\u5272\u308a\u5f53\u3066\u521d\u671f\u5316\u3059\u308b\u3002\n\u305d\u3057\u3066\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u304c1\u30da\u30fc\u30b8\u3088\u308a\u591a\u304f\u4f7f\u304a\u3046\u3068\u3057\u305f\u3089\u5931\u6557\u3059\u308b\u3088\u3046\u306b\u3059\u308b\u305f\u3081\u306b\u3001\u305d\u306e\u30b9\u30bf\u30c3\u30af\u7528\u306e\u30da\u30fc\u30b8\u306e\u4e0b\u4f4d\u306b\u30a2\u30af\u30bb\u30b9\u51fa\u6765\u306a\u3044\u30da\u30fc\u30b8\u3092\u4e00\u3064\u914d\u7f6e\u3059\u308b\u3002\n\u3053\u306e\u30a2\u30af\u30bb\u30b9\u51fa\u6765\u306a\u3044\u30da\u30fc\u30b8\u306f\u3001\u9577\u3059\u304e\u308b\u5f15\u6570\u306bexec\u304c\u5bfe\u51e6\u3059\u308b\u3053\u3068\u3082\u307e\u305f\u53ef\u80fd\u306b\u3059\u308b\u3002\n\u305d\u3046\u3044\u3046\u3068\u304d\uff08\u9577\u3059\u304e\u308b\u5f15\u6570\u304c\u6e21\u3055\u308c\u305f\u3068\u304d\uff09\u306f\u3001exec\u304c\u5f15\u6570\u3092\u30b9\u30bf\u30c3\u30af\u306b\u30b3\u30d4\u30fc\u3059\u308b\u305f\u3081\u306b\u4f7f\u3063\u3066\u308bcopyout\u95a2\u6570\u304c\u3001\u30b3\u30d4\u30fc\u5148\u306e\u30da\u30fc\u30b8\u304c\u30a2\u30af\u30bb\u30b9\u4e0d\u80fd\u3067\u3042\u308b\u4e8b\u3092\u691c\u77e5\u3057\u3001-1\u304c\u8fd4\u308b\u3002\n\nexec\u306f\u3001\u4e00\u5ea6\u306b\u4e00\u3064\u305a\u3064\u30b9\u30bf\u30c3\u30af\u306e\u30c8\u30c3\u30d7\u306b\u5f15\u6570\u306e\u6587\u5b57\u5217\u3092\u30b3\u30d4\u30fc\u3057\u3001\u305d\u3053\u306b\u5bfe\u3059\u308b\u30dd\u30a4\u30f3\u30bf\u3092ustack\u306b\u8a18\u9332\u3059\u308b\u3002\n\u305d\u3057\u3066\u3001main\u306b\u6e21\u3055\u308c\u308bargv\u306e\u30ea\u30b9\u30c8\u306b\u306a\u308b\u3067\u3042\u308d\u3046\u3082\u306e\u306e\u6700\u5f8c\u306b\u30cc\u30eb\u30dd\u30a4\u30f3\u30bf\u3092\u7f6e\u304f\u3002\n\u6700\u521d\u306e3\u3064\u306eustack\u306e\u9805\u76ee\u306f\u3001argv\u3068argc\u306e\u30dd\u30a4\u30f3\u30bf\u3068PC\u3078\u306e\u507d\u306e\u30ea\u30bf\u30fc\u30f3\uff08fake return PC\uff09\u3067\u3042\u308b\u3002\n\n\u65b0\u3057\u3044\u30e1\u30e2\u30ea\u30a4\u30fc\u76ee\u5730\u3092\u7528\u610f\u3057\u3066\u3044\u308b\u9593\u3001\u3082\u3057exec\u304c\u30d7\u30ed\u30b0\u30e9\u30e0\u30bb\u30b0\u30e1\u30f3\u30c8\u306e\u7570\u5e38\u306e\u3088\u3046\u306a\u30a8\u30e9\u30fc\u3092\u691c\u51fa\u3057\u305f\u3089\u3001bad\u30e9\u30d9\u30eb\u306b\u30b8\u30e3\u30f3\u30d7\u3057\u3001\u305d\u306e\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3057\u3001-1\u3092\u8fd4\u3059\u3002\nexec\u306f\u3001\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3059\u308b\u306e\u3092\u305d\u308c\u304c\u78ba\u5b9f\u306b\u306a\u308b\u307e\u3067\u5f85\u305f\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002\n\u3082\u3057\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u306e\u89e3\u653e\u304c\u5b8c\u4e86\u3057\u305f\u3089\u3001-1\u3092\u8fd4\u3059\u4e8b\u306f\u306a\u3044\u3002\nexec\u306b\u304a\u3051\u308b\u30a8\u30e9\u30fc\u306f\u3001\u30a4\u30e1\u30fc\u30b8\u306e\u751f\u6210\u3092\u3057\u3066\u308b\u9593\u3060\u3051\u8d77\u304d\u308b\u3002\n\u4e00\u5ea6\u30a4\u30e1\u30fc\u30b8\u304c\u5b8c\u4e86\u8a2d\u697d\u3001exec\u306f\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u30a4\u30f3\u30b9\u30fc\u30eb\u3057\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u3092\u89e3\u653e\u3059\u308b\u3053\u3068\u304c\u51fa\u6765\u308b\u3002\n\uff08exec\u95a2\u6570\u306ebad\u30e9\u30d9\u30eb\u306e\u76f4\u524d\u306e\u90e8\u5206\u3002switchuvm\u3068freevm\uff09\n\u6700\u5f8c\u306b\u3001exec\u306f0\u3092\u8fd4\u3059\u3002\n\u6210\u529f\u3060\uff01\n\n\u3053\u308c\u3067\u3001initcode\u306f\u5b8c\u4e86\u3057\u305f\u3002\nexec\u306f\u3001\u305d\u308c\u3092\/init\u30d0\u30a4\u30ca\u30ea\u3067\u7f6e\u304d\u63db\u3048\u3001loaded out of the file system.\uff08\u3053\u3053\u5206\u304b\u3089\u306a\u3044\uff09\ninit\u306f\u3001\u5fc5\u8981\u306a\u3089\u65b0\u3057\u3044\u30b3\u30f3\u30bd\u30fc\u30eb\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3092\u751f\u6210\u3057\u3001\u305d\u3057\u3066\u305d\u308c\u3092\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf0,1,2\u3068\u3057\u3066\u958b\u304f\u3002\n\u305d\u3057\u3066\u30eb\u30fc\u30d7\u3057\u3001\u30b3\u30f3\u30bd\u30fc\u30eb\u30b7\u30a7\u30eb\u3092\u958b\u59cb\u3057\u3001\u30b7\u30a7\u30eb\u304c\u7d42\u4e86\u3059\u308b\u307e\u3067\u89aa\u306e\u306a\u3044\u30be\u30f3\u30d3\u3092\u5236\u5fa1\u3057\u3001\u7e70\u308a\u8fd4\u3059\u3002\n\u3053\u308c\u3067\u30b7\u30b9\u30c6\u30e0\u306f\u8d77\u52d5\u3092\u5b8c\u4e86\u3057\u305f\u4e8b\u306b\u306a\u308b\u3002\n\ninit.c\u306e\u5168\u3066\n[sourcecode language="c"]\/\/ init: The initial user-level program\n\n#include "types.h"\n#include "stat.h"\n#include "user.h"\n#include "fcntl.h"\n\nchar *argv[] = { "sh", 0 };\n\nint\nmain(void)\n{\n int pid, wpid;\n\n if(open("console", O_RDWR) < 0){\n mknod("console", 1, 1);\n open("console", O_RDWR);\n }\n dup(0); \/\/ stdout\n dup(0); \/\/ stderr\n\n for(;;){\n printf(1, "init: starting sh\\n");\n pid = fork();\n if(pid < 0){\n printf(1, "init: fork failed\\n");\n exit();\n }\n if(pid == 0){\n exec("sh", argv);\n printf(1, "init: exec sh failed\\n");\n exit();\n }\n while((wpid=wait()) >= 0 && wpid != pid)\n printf(1, "zombie!\\n");\n }\n}<\/pre>\n\u30b7\u30b9\u30c6\u30e0\u304c\u8d77\u52d5\u5b8c\u4e86\u3057\u305f\u3068\u306f\u3044\u3048\u3001xv6\u306e\u91cd\u8981\u306a\u30b5\u30d6\u30b7\u30b9\u30c6\u30e0\u3092\u3044\u304f\u3064\u304b\u98db\u3070\u3057\u3066\u8aac\u660e\u3057\u3066\u304d\u305f\u3002
\n\u6b21\u306e\u7ae0\u3067\u306f\u3001int $T_SYSCALL\u306b\u3088\u3063\u3066\u5f15\u304d\u8d77\u3053\u3055\u308c\u308b\u5272\u308a\u8fbc\u307f\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u5236\u5fa1\u3055\u305b\u308b\u305f\u3081\u306bx86\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u3092\u3069\u3046\u3084\u3063\u3066xv6\u304c\u8a2d\u5b9a\u3059\u308b\u304b\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002
\n\u6b8b\u308a\u306e\u7ae0\u3067\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u7ba1\u7406\u3068\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u306b\u3064\u3044\u3066\u8aac\u660e\u3059\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
exec\u4e2d\u5fc3\u306e\u8a71\u3067\u3059\u3002
\n\u6700\u521d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u8d77\u52d5\u306b\u3082exec\u3092\u4f7f\u3046\u3093\u3067\u3059\u306d\u3002
\n\u3082\u3061\u308d\u3093\u3053\u308c\u307e\u3067\u306e\u7bc0\u3067\u3001\u6700\u521d\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u3044\u3048\u3069\u306a\u308b\u3079\u304f\u901a\u5e38\u306e\u30d7\u30ed\u30bb\u30b9\u3068\u540c\u3058\u3088\u3046\u306b\u6a19\u6e96\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u5229\u7528\u3057\u3066\u3044\u308b\u3068\u3044\u3046\u611f\u3058\u306e\u8aac\u660e\u304c\u3042\u3063\u305f\u306e\u3067\u305d\u3046\u9a5a\u304f\u3088\u3046\u306a\u3053\u3068\u3067\u306f\u306a\u3044\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n
\u9014\u4e2d\u306e\u8aac\u660e\u3067\u53e4\u3044\u30a4\u30e1\u30fc\u30b8\u306e\u89e3\u653e\u306e\u90e8\u5206\u306b\u4e00\u77ac\u304a\u3084\uff1f\u3068\u306a\u308a\u307e\u3057\u305f\u304c\u3001\u305d\u3082\u305d\u3082exec\u306f\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u90e8\u5206\u306a\u3069\u3092\u6b8b\u3057\u3066\u5143\u306e\u30a4\u30e1\u30fc\u30b8\u3092\u65b0\u3057\u3044\u30a4\u30e1\u30fc\u30b8\u3067\u7f6e\u304d\u63db\u3048\u308b\u306e\u304c\u901a\u5e38\u306e\u52d5\u4f5c\u3067\u3059\u3002
\n\uff08\u306a\u306e\u3067\u901a\u5e38\u4f7f\u3046\u3068\u304d\u306f\u305d\u306e\u524d\u306bfork\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3057\u305f\u306d\uff09
\n\u89e3\u653e\u306e\u8a71\u304c\u5165\u3063\u3066\u304f\u308b\u306e\u3082\u5f53\u7136\u3067\u3059\u306d\u3002<\/p>\n
\u3053\u306e\u7ae0\u306e\u8aac\u660e\u90e8\u5206\u306f\u7d42\u308f\u308a\u3067\u3059\u304c\u3001\u3042\u3068Real world\u3068\u3044\u3046\u7bc0\u3068Exercises\u3068\u3044\u3046\u7bc0\u304c\u6b8b\u3063\u3066\u307e\u3059\u3002
\n\u4e00\u5fdc\u5168\u90e8\u3084\u308b\u3064\u3082\u308a\u3067\u3059\u304cExercises\u306f\u3001\u3084\u308d\u3046\u3068\u601d\u3048\u3070\u3044\u304f\u3089\u3067\u3082\u6398\u308a\u4e0b\u3052\u308c\u305d\u3046\u306a\u6c17\u304c\u3059\u308b\u306e\u3067\u3001\u30b5\u30e9\u30c3\u3068\u7a0b\u5ea6\u306b\u3057\u3068\u304f\u3064\u3082\u308a\u3067\u3059\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[405],"class_list":["post-1307","post","type-post","status-publish","format-standard","hentry","category-tech","tag-xv6"],"_links":{"self":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1307","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/comments?post=1307"}],"version-history":[{"count":0,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1307\/revisions"}],"wp:attachment":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/media?parent=1307"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/categories?post=1307"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/tags?post=1307"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}