101 lines
2.3 KiB
C
101 lines
2.3 KiB
C
#include "types.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "x86.h"
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#include "elf.h"
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int
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exec(char *path, char **argv)
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{
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char *s, *last;
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int i, off;
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uint argc, sz, sp, ustack[3+MAXARG+1];
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struct elfhdr elf;
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struct inode *ip;
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struct proghdr ph;
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pde_t *pgdir, *oldpgdir;
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if((ip = namei(path)) == 0)
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return -1;
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ilock(ip);
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pgdir = 0;
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// Check ELF header
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if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
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goto bad;
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if(elf.magic != ELF_MAGIC)
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goto bad;
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if((pgdir = setupkvm(kalloc)) == 0)
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goto bad;
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// Load program into memory.
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sz = 0;
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for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
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if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
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goto bad;
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if(ph.type != ELF_PROG_LOAD)
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continue;
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if(ph.memsz < ph.filesz)
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goto bad;
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if((sz = allocuvm(pgdir, sz, ph.vaddr + ph.memsz)) == 0)
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goto bad;
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if(loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0)
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goto bad;
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}
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iunlockput(ip);
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ip = 0;
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// Allocate two pages at the next page boundary.
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// Make the first inaccessible. Use the second as the user stack.
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sz = PGROUNDUP(sz);
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if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)
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goto bad;
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clearpteu(pgdir, (char*)(sz - 2*PGSIZE));
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sp = sz;
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// Push argument strings, prepare rest of stack in ustack.
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for(argc = 0; argv[argc]; argc++) {
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if(argc >= MAXARG)
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goto bad;
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sp = (sp - (strlen(argv[argc]) + 1)) & ~3;
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if(copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0)
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goto bad;
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ustack[3+argc] = sp;
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}
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ustack[3+argc] = 0;
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ustack[0] = 0xffffffff; // fake return PC
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ustack[1] = argc;
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ustack[2] = sp - (argc+1)*4; // argv pointer
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sp -= (3+argc+1) * 4;
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if(copyout(pgdir, sp, ustack, (3+argc+1)*4) < 0)
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goto bad;
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// Save program name for debugging.
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for(last=s=path; *s; s++)
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if(*s == '/')
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last = s+1;
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safestrcpy(proc->name, last, sizeof(proc->name));
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// Commit to the user image.
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oldpgdir = proc->pgdir;
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proc->pgdir = pgdir;
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proc->sz = sz;
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proc->tf->eip = elf.entry; // main
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proc->tf->esp = sp;
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switchuvm(proc);
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freevm(oldpgdir);
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return 0;
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bad:
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if(pgdir)
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freevm(pgdir);
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if(ip)
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iunlockput(ip);
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return -1;
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}
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